Merge pull request #505 from grafana/zenador/sync-upstream-22-may-2023

Sync upstream 24 may 2023

.promu.yml

@@ -14,8 +14,10 @@ build:
         all:
             - netgo
             - builtinassets
+            - stringlabels
         windows:
             - builtinassets
+            - stringlabels
     flags: -a
     ldflags: |
         -X github.com/prometheus/common/version.Version={{.Version}}

CHANGELOG.md

@@ -1,5 +1,29 @@
 # Changelog
 
+## 2.44.0 / 2023-05-13
+
+This version is built with Go tag `stringlabels`, to use the smaller data
+structure for Labels that was optional in the previous release. For more
+details about this code change see #10991.
+
+* [CHANGE] Remote-write: Raise default samples per send to 2,000. #12203
+* [FEATURE] Remote-read: Handle native histograms. #12085, #12192
+* [FEATURE] Promtool: Health and readiness check of prometheus server in CLI. #12096
+* [FEATURE] PromQL: Add `query_samples_total` metric, the total number of samples loaded by all queries. #12251
+* [ENHANCEMENT] Storage: Optimise buffer used to iterate through samples. #12326
+* [ENHANCEMENT] Scrape: Reduce memory allocations on target labels. #12084
+* [ENHANCEMENT] PromQL: Use faster heap method for `topk()` / `bottomk()`. #12190
+* [ENHANCEMENT] Rules API: Allow filtering by rule name. #12270
+* [ENHANCEMENT] Native Histograms: Various fixes and improvements. #11687, #12264, #12272
+* [ENHANCEMENT] UI: Search of scraping pools is now case-insensitive. #12207
+* [ENHANCEMENT] TSDB: Add an affirmative log message for successful WAL repair. #12135
+* [BUGFIX] TSDB: Block compaction failed when shutting down. #12179
+* [BUGFIX] TSDB: Out-of-order chunks could be ignored if the write-behind log was deleted. #12127
+
+## 2.43.1 / 2023-05-03
+
+* [BUGFIX] Labels: `Set()` after `Del()` would be ignored, which broke some relabeling rules. #12322
+
 ## 2.43.0 / 2023-03-21
 
 We are working on some performance improvements in Prometheus, which are only
@@ -13,7 +37,7 @@ the gains on their production architecture. We are providing release artefacts
 improvements for testing. #10991
 
 * [FEATURE] Promtool: Add HTTP client configuration to query commands. #11487
-* [FEATURE] Scrape: Add `include_scrape_configs` to include scrape configs from different files. #12019
+* [FEATURE] Scrape: Add `scrape_config_files` to include scrape configs from different files. #12019
 * [FEATURE] HTTP client: Add `no_proxy` to exclude URLs from proxied requests. #12098
 * [FEATURE] HTTP client: Add `proxy_from_enviroment` to read proxies from env variables. #12098
 * [ENHANCEMENT] API: Add support for setting lookback delta per query via the API. #12088

VERSION

@@ -1 +1 @@
-2.43.0
+2.44.0

cmd/prometheus/main.go

@@ -337,6 +337,9 @@ func main() {
 	serverOnlyFlag(a, "storage.tsdb.head-chunks-write-queue-size", "Size of the queue through which head chunks are written to the disk to be m-mapped, 0 disables the queue completely. Experimental.").
 		Default("0").IntVar(&cfg.tsdb.HeadChunksWriteQueueSize)
 
+	serverOnlyFlag(a, "storage.tsdb.samples-per-chunk", "Target number of samples per chunk.").
+		Default("120").Hidden().IntVar(&cfg.tsdb.SamplesPerChunk)
+
 	agentOnlyFlag(a, "storage.agent.path", "Base path for metrics storage.").
 		Default("data-agent/").StringVar(&cfg.agentStoragePath)
 
@@ -1050,6 +1053,7 @@ func main() {
 
 				startTimeMargin := int64(2 * time.Duration(cfg.tsdb.MinBlockDuration).Seconds() * 1000)
 				localStorage.Set(db, startTimeMargin)
+				db.SetWriteNotified(remoteStorage)
 				close(dbOpen)
 				<-cancel
 				return nil
@@ -1482,11 +1486,11 @@ func (s *readyStorage) Snapshot(dir string, withHead bool) error {
 }
 
 // Stats implements the api_v1.TSDBAdminStats interface.
-func (s *readyStorage) Stats(statsByLabelName string) (*tsdb.Stats, error) {
+func (s *readyStorage) Stats(statsByLabelName string, limit int) (*tsdb.Stats, error) {
 	if x := s.get(); x != nil {
 		switch db := x.(type) {
 		case *tsdb.DB:
-			return db.Head().Stats(statsByLabelName), nil
+			return db.Head().Stats(statsByLabelName, limit), nil
 		case *agent.DB:
 			return nil, agent.ErrUnsupported
 		default:
@@ -1543,6 +1547,7 @@ type tsdbOptions struct {
 	NoLockfile                     bool
 	WALCompression                 bool
 	HeadChunksWriteQueueSize       int
+	SamplesPerChunk                int
 	StripeSize                     int
 	MinBlockDuration               model.Duration
 	MaxBlockDuration               model.Duration
@@ -1563,6 +1568,7 @@ func (opts tsdbOptions) ToTSDBOptions() tsdb.Options {
 		AllowOverlappingCompaction:     true,
 		WALCompression:                 opts.WALCompression,
 		HeadChunksWriteQueueSize:       opts.HeadChunksWriteQueueSize,
+		SamplesPerChunk:                opts.SamplesPerChunk,
 		StripeSize:                     opts.StripeSize,
 		MinBlockDuration:               int64(time.Duration(opts.MinBlockDuration) / time.Millisecond),
 		MaxBlockDuration:               int64(time.Duration(opts.MaxBlockDuration) / time.Millisecond),

config/config.go

@@ -146,8 +146,9 @@ var (
 
 	// DefaultScrapeConfig is the default scrape configuration.
 	DefaultScrapeConfig = ScrapeConfig{
-		// ScrapeTimeout and ScrapeInterval default to the
+		// ScrapeTimeout and ScrapeInterval default to the configured
-		// configured globals.
+		// globals.
+		ScrapeClassicHistograms: false,
 		MetricsPath:             "/metrics",
 		Scheme:                  "http",
 		HonorLabels:             false,
@@ -467,6 +468,8 @@ type ScrapeConfig struct {
 	ScrapeInterval model.Duration `yaml:"scrape_interval,omitempty"`
 	// The timeout for scraping targets of this config.
 	ScrapeTimeout model.Duration `yaml:"scrape_timeout,omitempty"`
+	// Whether to scrape a classic histogram that is also exposed as a native histogram.
+	ScrapeClassicHistograms bool `yaml:"scrape_classic_histograms,omitempty"`
 	// The HTTP resource path on which to fetch metrics from targets.
 	MetricsPath string `yaml:"metrics_path,omitempty"`
 	// The URL scheme with which to fetch metrics from targets.
@@ -489,6 +492,9 @@ type ScrapeConfig struct {
 	// More than this label value length post metric-relabeling will cause the
 	// scrape to fail.
 	LabelValueLengthLimit uint `yaml:"label_value_length_limit,omitempty"`
+	// More than this many buckets in a native histogram will cause the scrape to
+	// fail.
+	NativeHistogramBucketLimit uint `yaml:"native_histogram_bucket_limit,omitempty"`
 
 	// We cannot do proper Go type embedding below as the parser will then parse
 	// values arbitrarily into the overflow maps of further-down types.

config/config_test.go

@@ -363,6 +363,7 @@ var expectedConf = &Config{
 			ServiceDiscoveryConfigs: discovery.Configs{
 				&consul.SDConfig{
 					Server:          "localhost:1234",
+					PathPrefix:      "/consul",
 					Token:           "mysecret",
 					Services:        []string{"nginx", "cache", "mysql"},
 					ServiceTags:     []string{"canary", "v1"},

config/testdata/conf.good.yml

@@ -151,6 +151,7 @@ scrape_configs:
     consul_sd_configs:
       - server: "localhost:1234"
         token: mysecret
+        path_prefix: /consul
         services: ["nginx", "cache", "mysql"]
         tags: ["canary", "v1"]
         node_meta:

discovery/consul/consul.go

@@ -111,6 +111,7 @@ func init() {
 // SDConfig is the configuration for Consul service discovery.
 type SDConfig struct {
 	Server       string        `yaml:"server,omitempty"`
+	PathPrefix   string        `yaml:"path_prefix,omitempty"`
 	Token        config.Secret `yaml:"token,omitempty"`
 	Datacenter   string        `yaml:"datacenter,omitempty"`
 	Namespace    string        `yaml:"namespace,omitempty"`
@@ -211,6 +212,7 @@ func NewDiscovery(conf *SDConfig, logger log.Logger) (*Discovery, error) {
 
 	clientConf := &consul.Config{
 		Address:    conf.Server,
+		PathPrefix: conf.PathPrefix,
 		Scheme:     conf.Scheme,
 		Datacenter: conf.Datacenter,
 		Namespace:  conf.Namespace,

discovery/kubernetes/endpoints.go

@@ -305,7 +305,11 @@ func (e *Endpoints) buildEndpoints(eps *apiv1.Endpoints) *targetgroup.Group {
 		}
 
 		if e.withNodeMetadata {
+			if addr.NodeName != nil {
 				target = addNodeLabels(target, e.nodeInf, e.logger, addr.NodeName)
+			} else if addr.TargetRef != nil && addr.TargetRef.Kind == "Node" {
+				target = addNodeLabels(target, e.nodeInf, e.logger, &addr.TargetRef.Name)
+			}
 		}
 
 		pod := e.resolvePodRef(addr.TargetRef)
@@ -466,5 +470,6 @@ func addNodeLabels(tg model.LabelSet, nodeInf cache.SharedInformer, logger log.L
 		nodeLabelset[model.LabelName(nodeLabelPrefix+ln)] = lv(v)
 		nodeLabelset[model.LabelName(nodeLabelPresentPrefix+ln)] = presentValue
 	}
+
 	return tg.Merge(nodeLabelset)
 }

discovery/kubernetes/endpoints_test.go

@@ -69,6 +69,24 @@ func makeEndpoints() *v1.Endpoints {
 					},
 				},
 			},
+			{
+				Addresses: []v1.EndpointAddress{
+					{
+						IP: "6.7.8.9",
+						TargetRef: &v1.ObjectReference{
+							Kind: "Node",
+							Name: "barbaz",
+						},
+					},
+				},
+				Ports: []v1.EndpointPort{
+					{
+						Name:     "testport",
+						Port:     9002,
+						Protocol: v1.ProtocolTCP,
+					},
+				},
+			},
 		},
 	}
 }
@@ -106,6 +124,14 @@ func TestEndpointsDiscoveryBeforeRun(t *testing.T) {
 						"__meta_kubernetes_endpoint_port_protocol": "TCP",
 						"__meta_kubernetes_endpoint_ready":         "false",
 					},
+					{
+						"__address__": "6.7.8.9:9002",
+						"__meta_kubernetes_endpoint_address_target_kind": "Node",
+						"__meta_kubernetes_endpoint_address_target_name": "barbaz",
+						"__meta_kubernetes_endpoint_port_name":           "testport",
+						"__meta_kubernetes_endpoint_port_protocol":       "TCP",
+						"__meta_kubernetes_endpoint_ready":               "true",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_namespace":      "default",
@@ -398,6 +424,14 @@ func TestEndpointsDiscoveryWithService(t *testing.T) {
 						"__meta_kubernetes_endpoint_port_protocol": "TCP",
 						"__meta_kubernetes_endpoint_ready":         "false",
 					},
+					{
+						"__address__": "6.7.8.9:9002",
+						"__meta_kubernetes_endpoint_address_target_kind": "Node",
+						"__meta_kubernetes_endpoint_address_target_name": "barbaz",
+						"__meta_kubernetes_endpoint_port_name":           "testport",
+						"__meta_kubernetes_endpoint_port_protocol":       "TCP",
+						"__meta_kubernetes_endpoint_ready":               "true",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_namespace":                     "default",
@@ -466,6 +500,14 @@ func TestEndpointsDiscoveryWithServiceUpdate(t *testing.T) {
 						"__meta_kubernetes_endpoint_port_protocol": "TCP",
 						"__meta_kubernetes_endpoint_ready":         "false",
 					},
+					{
+						"__address__": "6.7.8.9:9002",
+						"__meta_kubernetes_endpoint_address_target_kind": "Node",
+						"__meta_kubernetes_endpoint_address_target_name": "barbaz",
+						"__meta_kubernetes_endpoint_port_name":           "testport",
+						"__meta_kubernetes_endpoint_port_protocol":       "TCP",
+						"__meta_kubernetes_endpoint_ready":               "true",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_namespace":                      "default",
@@ -484,8 +526,10 @@ func TestEndpointsDiscoveryWithServiceUpdate(t *testing.T) {
 
 func TestEndpointsDiscoveryWithNodeMetadata(t *testing.T) {
 	metadataConfig := AttachMetadataConfig{Node: true}
-	nodeLabels := map[string]string{"az": "us-east1"}
+	nodeLabels1 := map[string]string{"az": "us-east1"}
-	node := makeNode("foobar", "", "", nodeLabels, nil)
+	nodeLabels2 := map[string]string{"az": "us-west2"}
+	node1 := makeNode("foobar", "", "", nodeLabels1, nil)
+	node2 := makeNode("barbaz", "", "", nodeLabels2, nil)
 	svc := &v1.Service{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:      "testendpoints",
@@ -495,7 +539,7 @@ func TestEndpointsDiscoveryWithNodeMetadata(t *testing.T) {
 			},
 		},
 	}
-	n, _ := makeDiscoveryWithMetadata(RoleEndpoint, NamespaceDiscovery{}, metadataConfig, makeEndpoints(), svc, node)
+	n, _ := makeDiscoveryWithMetadata(RoleEndpoint, NamespaceDiscovery{}, metadataConfig, makeEndpoints(), svc, node1, node2)
 
 	k8sDiscoveryTest{
 		discovery:        n,
@@ -526,6 +570,17 @@ func TestEndpointsDiscoveryWithNodeMetadata(t *testing.T) {
 						"__meta_kubernetes_endpoint_port_protocol": "TCP",
 						"__meta_kubernetes_endpoint_ready":         "false",
 					},
+					{
+						"__address__": "6.7.8.9:9002",
+						"__meta_kubernetes_endpoint_address_target_kind": "Node",
+						"__meta_kubernetes_endpoint_address_target_name": "barbaz",
+						"__meta_kubernetes_endpoint_port_name":           "testport",
+						"__meta_kubernetes_endpoint_port_protocol":       "TCP",
+						"__meta_kubernetes_endpoint_ready":               "true",
+						"__meta_kubernetes_node_label_az":                "us-west2",
+						"__meta_kubernetes_node_labelpresent_az":         "true",
+						"__meta_kubernetes_node_name":                    "barbaz",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_namespace":                     "default",
@@ -541,8 +596,10 @@ func TestEndpointsDiscoveryWithNodeMetadata(t *testing.T) {
 }
 
 func TestEndpointsDiscoveryWithUpdatedNodeMetadata(t *testing.T) {
-	nodeLabels := map[string]string{"az": "us-east1"}
+	nodeLabels1 := map[string]string{"az": "us-east1"}
-	nodes := makeNode("foobar", "", "", nodeLabels, nil)
+	nodeLabels2 := map[string]string{"az": "us-west2"}
+	node1 := makeNode("foobar", "", "", nodeLabels1, nil)
+	node2 := makeNode("barbaz", "", "", nodeLabels2, nil)
 	metadataConfig := AttachMetadataConfig{Node: true}
 	svc := &v1.Service{
 		ObjectMeta: metav1.ObjectMeta{
@@ -553,13 +610,13 @@ func TestEndpointsDiscoveryWithUpdatedNodeMetadata(t *testing.T) {
 			},
 		},
 	}
-	n, c := makeDiscoveryWithMetadata(RoleEndpoint, NamespaceDiscovery{}, metadataConfig, makeEndpoints(), nodes, svc)
+	n, c := makeDiscoveryWithMetadata(RoleEndpoint, NamespaceDiscovery{}, metadataConfig, makeEndpoints(), node1, node2, svc)
 
 	k8sDiscoveryTest{
 		discovery: n,
 		afterStart: func() {
-			nodes.Labels["az"] = "eu-central1"
+			node1.Labels["az"] = "eu-central1"
-			c.CoreV1().Nodes().Update(context.Background(), nodes, metav1.UpdateOptions{})
+			c.CoreV1().Nodes().Update(context.Background(), node1, metav1.UpdateOptions{})
 		},
 		expectedMaxItems: 2,
 		expectedRes: map[string]*targetgroup.Group{
@@ -572,7 +629,7 @@ func TestEndpointsDiscoveryWithUpdatedNodeMetadata(t *testing.T) {
 						"__meta_kubernetes_endpoint_port_name":     "testport",
 						"__meta_kubernetes_endpoint_port_protocol": "TCP",
 						"__meta_kubernetes_endpoint_ready":         "true",
-						"__meta_kubernetes_node_label_az":          "eu-central1",
+						"__meta_kubernetes_node_label_az":          "us-east1",
 						"__meta_kubernetes_node_labelpresent_az":   "true",
 						"__meta_kubernetes_node_name":              "foobar",
 					},
@@ -588,6 +645,17 @@ func TestEndpointsDiscoveryWithUpdatedNodeMetadata(t *testing.T) {
 						"__meta_kubernetes_endpoint_port_protocol": "TCP",
 						"__meta_kubernetes_endpoint_ready":         "false",
 					},
+					{
+						"__address__": "6.7.8.9:9002",
+						"__meta_kubernetes_endpoint_address_target_kind": "Node",
+						"__meta_kubernetes_endpoint_address_target_name": "barbaz",
+						"__meta_kubernetes_endpoint_port_name":           "testport",
+						"__meta_kubernetes_endpoint_port_protocol":       "TCP",
+						"__meta_kubernetes_endpoint_ready":               "true",
+						"__meta_kubernetes_node_label_az":                "us-west2",
+						"__meta_kubernetes_node_labelpresent_az":         "true",
+						"__meta_kubernetes_node_name":                    "barbaz",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_namespace":                     "default",
@@ -699,6 +767,14 @@ func TestEndpointsDiscoveryNamespaces(t *testing.T) {
 						"__meta_kubernetes_endpoint_port_protocol": "TCP",
 						"__meta_kubernetes_endpoint_ready":         "false",
 					},
+					{
+						"__address__": "6.7.8.9:9002",
+						"__meta_kubernetes_endpoint_address_target_kind": "Node",
+						"__meta_kubernetes_endpoint_address_target_name": "barbaz",
+						"__meta_kubernetes_endpoint_port_name":           "testport",
+						"__meta_kubernetes_endpoint_port_protocol":       "TCP",
+						"__meta_kubernetes_endpoint_ready":               "true",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_namespace":                "ns1",
@@ -815,6 +891,14 @@ func TestEndpointsDiscoveryOwnNamespace(t *testing.T) {
 						"__meta_kubernetes_endpoint_port_protocol": "TCP",
 						"__meta_kubernetes_endpoint_ready":         "false",
 					},
+					{
+						"__address__": "6.7.8.9:9002",
+						"__meta_kubernetes_endpoint_address_target_kind": "Node",
+						"__meta_kubernetes_endpoint_address_target_name": "barbaz",
+						"__meta_kubernetes_endpoint_port_name":           "testport",
+						"__meta_kubernetes_endpoint_port_protocol":       "TCP",
+						"__meta_kubernetes_endpoint_ready":               "true",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_namespace":      "own-ns",

discovery/kubernetes/endpointslice.go

@@ -339,8 +339,12 @@ func (e *EndpointSlice) buildEndpointSlice(eps endpointSliceAdaptor) *targetgrou
 		}
 
 		if e.withNodeMetadata {
+			if ep.targetRef() != nil && ep.targetRef().Kind == "Node" {
+				target = addNodeLabels(target, e.nodeInf, e.logger, &ep.targetRef().Name)
+			} else {
 				target = addNodeLabels(target, e.nodeInf, e.logger, ep.nodename())
 			}
+		}
 
 		pod := e.resolvePodRef(ep.targetRef())
 		if pod == nil {

discovery/kubernetes/endpointslice_test.go

@@ -90,6 +90,17 @@ func makeEndpointSliceV1() *v1.EndpointSlice {
 					Serving:     boolptr(true),
 					Terminating: boolptr(true),
 				},
+			}, {
+				Addresses: []string{"4.5.6.7"},
+				Conditions: v1.EndpointConditions{
+					Ready:       boolptr(true),
+					Serving:     boolptr(true),
+					Terminating: boolptr(false),
+				},
+				TargetRef: &corev1.ObjectReference{
+					Kind: "Node",
+					Name: "barbaz",
+				},
 			},
 		},
 	}
@@ -130,6 +141,17 @@ func makeEndpointSliceV1beta1() *v1beta1.EndpointSlice {
 					Serving:     boolptr(true),
 					Terminating: boolptr(true),
 				},
+			}, {
+				Addresses: []string{"4.5.6.7"},
+				Conditions: v1beta1.EndpointConditions{
+					Ready:       boolptr(true),
+					Serving:     boolptr(true),
+					Terminating: boolptr(false),
+				},
+				TargetRef: &corev1.ObjectReference{
+					Kind: "Node",
+					Name: "barbaz",
+				},
 			},
 		},
 	}
@@ -183,6 +205,18 @@ func TestEndpointSliceDiscoveryBeforeRun(t *testing.T) {
 						"__meta_kubernetes_endpointslice_port_name":                       "testport",
 						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
 					},
+					{
+						"__address__": "4.5.6.7:9000",
+						"__meta_kubernetes_endpointslice_address_target_kind":             "Node",
+						"__meta_kubernetes_endpointslice_address_target_name":             "barbaz",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_ready":       "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_serving":     "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_terminating": "false",
+						"__meta_kubernetes_endpointslice_port":                            "9000",
+						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
+						"__meta_kubernetes_endpointslice_port_name":                       "testport",
+						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_endpointslice_address_type": "IPv4",
@@ -233,6 +267,17 @@ func TestEndpointSliceDiscoveryBeforeRunV1beta1(t *testing.T) {
 						"__meta_kubernetes_endpointslice_port_name":                       "testport",
 						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
 					},
+					{
+						"__address__": "4.5.6.7:9000",
+						"__meta_kubernetes_endpointslice_address_target_kind":             "Node",
+						"__meta_kubernetes_endpointslice_address_target_name":             "barbaz",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_ready":       "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_serving":     "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_terminating": "false",
+						"__meta_kubernetes_endpointslice_port":                            "9000",
+						"__meta_kubernetes_endpointslice_port_name":                       "testport",
+						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_endpointslice_address_type": "IPv4",
@@ -419,6 +464,18 @@ func TestEndpointSliceDiscoveryDelete(t *testing.T) {
 						"__meta_kubernetes_endpointslice_port_name":                       "testport",
 						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
 					},
+					{
+						"__address__": "4.5.6.7:9000",
+						"__meta_kubernetes_endpointslice_address_target_kind":             "Node",
+						"__meta_kubernetes_endpointslice_address_target_name":             "barbaz",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_ready":       "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_serving":     "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_terminating": "false",
+						"__meta_kubernetes_endpointslice_port":                            "9000",
+						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
+						"__meta_kubernetes_endpointslice_port_name":                       "testport",
+						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
+					},
 				},
 				Labels: map[model.LabelName]model.LabelValue{
 					"__meta_kubernetes_endpointslice_address_type": "IPv4",
@@ -503,6 +560,18 @@ func TestEndpointSliceDiscoveryUpdate(t *testing.T) {
 						"__meta_kubernetes_endpointslice_port_name":                       "testport",
 						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
 					},
+					{
+						"__address__": "4.5.6.7:9000",
+						"__meta_kubernetes_endpointslice_address_target_kind":             "Node",
+						"__meta_kubernetes_endpointslice_address_target_name":             "barbaz",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_ready":       "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_serving":     "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_terminating": "false",
+						"__meta_kubernetes_endpointslice_port":                            "9000",
+						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
+						"__meta_kubernetes_endpointslice_port_name":                       "testport",
+						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_endpointslice_address_type": "IPv4",
@@ -576,6 +645,18 @@ func TestEndpointSliceDiscoveryEmptyEndpoints(t *testing.T) {
 						"__meta_kubernetes_endpointslice_port_name":                       "testport",
 						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
 					},
+					{
+						"__address__": "4.5.6.7:9000",
+						"__meta_kubernetes_endpointslice_address_target_kind":             "Node",
+						"__meta_kubernetes_endpointslice_address_target_name":             "barbaz",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_ready":       "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_serving":     "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_terminating": "false",
+						"__meta_kubernetes_endpointslice_port":                            "9000",
+						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
+						"__meta_kubernetes_endpointslice_port_name":                       "testport",
+						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_endpointslice_address_type": "IPv4",
@@ -644,6 +725,18 @@ func TestEndpointSliceDiscoveryWithService(t *testing.T) {
 						"__meta_kubernetes_endpointslice_port_name":                       "testport",
 						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
 					},
+					{
+						"__address__": "4.5.6.7:9000",
+						"__meta_kubernetes_endpointslice_address_target_kind":             "Node",
+						"__meta_kubernetes_endpointslice_address_target_name":             "barbaz",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_ready":       "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_serving":     "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_terminating": "false",
+						"__meta_kubernetes_endpointslice_port":                            "9000",
+						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
+						"__meta_kubernetes_endpointslice_port_name":                       "testport",
+						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_endpointslice_address_type":    "IPv4",
@@ -728,6 +821,18 @@ func TestEndpointSliceDiscoveryWithServiceUpdate(t *testing.T) {
 						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
 						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
 					},
+					{
+						"__address__": "4.5.6.7:9000",
+						"__meta_kubernetes_endpointslice_address_target_kind":             "Node",
+						"__meta_kubernetes_endpointslice_address_target_name":             "barbaz",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_ready":       "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_serving":     "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_terminating": "false",
+						"__meta_kubernetes_endpointslice_port":                            "9000",
+						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
+						"__meta_kubernetes_endpointslice_port_name":                       "testport",
+						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_endpointslice_address_type":     "IPv4",
@@ -747,7 +852,8 @@ func TestEndpointSliceDiscoveryWithServiceUpdate(t *testing.T) {
 
 func TestEndpointsSlicesDiscoveryWithNodeMetadata(t *testing.T) {
 	metadataConfig := AttachMetadataConfig{Node: true}
-	nodeLabels := map[string]string{"az": "us-east1"}
+	nodeLabels1 := map[string]string{"az": "us-east1"}
+	nodeLabels2 := map[string]string{"az": "us-west2"}
 	svc := &corev1.Service{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:      "testendpoints",
@@ -757,7 +863,7 @@ func TestEndpointsSlicesDiscoveryWithNodeMetadata(t *testing.T) {
 			},
 		},
 	}
-	objs := []runtime.Object{makeEndpointSliceV1(), makeNode("foobar", "", "", nodeLabels, nil), svc}
+	objs := []runtime.Object{makeEndpointSliceV1(), makeNode("foobar", "", "", nodeLabels1, nil), makeNode("barbaz", "", "", nodeLabels2, nil), svc}
 	n, _ := makeDiscoveryWithMetadata(RoleEndpointSlice, NamespaceDiscovery{}, metadataConfig, objs...)
 
 	k8sDiscoveryTest{
@@ -804,6 +910,21 @@ func TestEndpointsSlicesDiscoveryWithNodeMetadata(t *testing.T) {
 						"__meta_kubernetes_endpointslice_port_name":                       "testport",
 						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
 					},
+					{
+						"__address__": "4.5.6.7:9000",
+						"__meta_kubernetes_endpointslice_address_target_kind":             "Node",
+						"__meta_kubernetes_endpointslice_address_target_name":             "barbaz",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_ready":       "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_serving":     "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_terminating": "false",
+						"__meta_kubernetes_endpointslice_port":                            "9000",
+						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
+						"__meta_kubernetes_endpointslice_port_name":                       "testport",
+						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
+						"__meta_kubernetes_node_label_az":                                 "us-west2",
+						"__meta_kubernetes_node_labelpresent_az":                          "true",
+						"__meta_kubernetes_node_name":                                     "barbaz",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_endpointslice_address_type":    "IPv4",
@@ -821,7 +942,8 @@ func TestEndpointsSlicesDiscoveryWithNodeMetadata(t *testing.T) {
 
 func TestEndpointsSlicesDiscoveryWithUpdatedNodeMetadata(t *testing.T) {
 	metadataConfig := AttachMetadataConfig{Node: true}
-	nodeLabels := map[string]string{"az": "us-east1"}
+	nodeLabels1 := map[string]string{"az": "us-east1"}
+	nodeLabels2 := map[string]string{"az": "us-west2"}
 	svc := &corev1.Service{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:      "testendpoints",
@@ -831,16 +953,17 @@ func TestEndpointsSlicesDiscoveryWithUpdatedNodeMetadata(t *testing.T) {
 			},
 		},
 	}
-	node := makeNode("foobar", "", "", nodeLabels, nil)
+	node1 := makeNode("foobar", "", "", nodeLabels1, nil)
-	objs := []runtime.Object{makeEndpointSliceV1(), node, svc}
+	node2 := makeNode("barbaz", "", "", nodeLabels2, nil)
+	objs := []runtime.Object{makeEndpointSliceV1(), node1, node2, svc}
 	n, c := makeDiscoveryWithMetadata(RoleEndpointSlice, NamespaceDiscovery{}, metadataConfig, objs...)
 
 	k8sDiscoveryTest{
 		discovery:        n,
 		expectedMaxItems: 2,
 		afterStart: func() {
-			node.Labels["az"] = "us-central1"
+			node1.Labels["az"] = "us-central1"
-			c.CoreV1().Nodes().Update(context.Background(), node, metav1.UpdateOptions{})
+			c.CoreV1().Nodes().Update(context.Background(), node1, metav1.UpdateOptions{})
 		},
 		expectedRes: map[string]*targetgroup.Group{
 			"endpointslice/default/testendpoints": {
@@ -859,7 +982,7 @@ func TestEndpointsSlicesDiscoveryWithUpdatedNodeMetadata(t *testing.T) {
 						"__meta_kubernetes_endpointslice_port_app_protocol":                  "http",
 						"__meta_kubernetes_endpointslice_port_name":                          "testport",
 						"__meta_kubernetes_endpointslice_port_protocol":                      "TCP",
-						"__meta_kubernetes_node_label_az":                                    "us-central1",
+						"__meta_kubernetes_node_label_az":                                    "us-east1",
 						"__meta_kubernetes_node_labelpresent_az":                             "true",
 						"__meta_kubernetes_node_name":                                        "foobar",
 					},
@@ -883,6 +1006,21 @@ func TestEndpointsSlicesDiscoveryWithUpdatedNodeMetadata(t *testing.T) {
 						"__meta_kubernetes_endpointslice_port_name":                       "testport",
 						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
 					},
+					{
+						"__address__": "4.5.6.7:9000",
+						"__meta_kubernetes_endpointslice_address_target_kind":             "Node",
+						"__meta_kubernetes_endpointslice_address_target_name":             "barbaz",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_ready":       "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_serving":     "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_terminating": "false",
+						"__meta_kubernetes_endpointslice_port":                            "9000",
+						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
+						"__meta_kubernetes_endpointslice_port_name":                       "testport",
+						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
+						"__meta_kubernetes_node_label_az":                                 "us-west2",
+						"__meta_kubernetes_node_labelpresent_az":                          "true",
+						"__meta_kubernetes_node_name":                                     "barbaz",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_endpointslice_address_type":    "IPv4",
@@ -1007,6 +1145,18 @@ func TestEndpointSliceDiscoveryNamespaces(t *testing.T) {
 						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
 						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
 					},
+					{
+						"__address__": "4.5.6.7:9000",
+						"__meta_kubernetes_endpointslice_address_target_kind":             "Node",
+						"__meta_kubernetes_endpointslice_address_target_name":             "barbaz",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_ready":       "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_serving":     "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_terminating": "false",
+						"__meta_kubernetes_endpointslice_port":                            "9000",
+						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
+						"__meta_kubernetes_endpointslice_port_name":                       "testport",
+						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_endpointslice_address_type": "IPv4",
@@ -1139,6 +1289,18 @@ func TestEndpointSliceDiscoveryOwnNamespace(t *testing.T) {
 						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
 						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
 					},
+					{
+						"__address__": "4.5.6.7:9000",
+						"__meta_kubernetes_endpointslice_address_target_kind":             "Node",
+						"__meta_kubernetes_endpointslice_address_target_name":             "barbaz",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_ready":       "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_serving":     "true",
+						"__meta_kubernetes_endpointslice_endpoint_conditions_terminating": "false",
+						"__meta_kubernetes_endpointslice_port":                            "9000",
+						"__meta_kubernetes_endpointslice_port_app_protocol":               "http",
+						"__meta_kubernetes_endpointslice_port_name":                       "testport",
+						"__meta_kubernetes_endpointslice_port_protocol":                   "TCP",
+					},
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_endpointslice_address_type": "IPv4",

discovery/kubernetes/kubernetes.go

@@ -761,16 +761,22 @@ func (d *Discovery) newEndpointsByNodeInformer(plw *cache.ListWatch) cache.Share
 	indexers[nodeIndex] = func(obj interface{}) ([]string, error) {
 		e, ok := obj.(*apiv1.Endpoints)
 		if !ok {
-			return nil, fmt.Errorf("object is not a pod")
+			return nil, fmt.Errorf("object is not endpoints")
 		}
 		var nodes []string
 		for _, target := range e.Subsets {
 			for _, addr := range target.Addresses {
-				if addr.NodeName == nil {
+				if addr.TargetRef != nil {
-					continue
+					switch addr.TargetRef.Kind {
-				}
+					case "Pod":
+						if addr.NodeName != nil {
 							nodes = append(nodes, *addr.NodeName)
 						}
+					case "Node":
+						nodes = append(nodes, addr.TargetRef.Name)
+					}
+				}
+			}
 		}
 		return nodes, nil
 	}
@@ -789,18 +795,30 @@ func (d *Discovery) newEndpointSlicesByNodeInformer(plw *cache.ListWatch, object
 		switch e := obj.(type) {
 		case *disv1.EndpointSlice:
 			for _, target := range e.Endpoints {
-				if target.NodeName == nil {
+				if target.TargetRef != nil {
-					continue
+					switch target.TargetRef.Kind {
-				}
+					case "Pod":
+						if target.NodeName != nil {
 							nodes = append(nodes, *target.NodeName)
 						}
+					case "Node":
+						nodes = append(nodes, target.TargetRef.Name)
+					}
+				}
+			}
 		case *disv1beta1.EndpointSlice:
 			for _, target := range e.Endpoints {
-				if target.NodeName == nil {
+				if target.TargetRef != nil {
-					continue
+					switch target.TargetRef.Kind {
-				}
+					case "Pod":
+						if target.NodeName != nil {
 							nodes = append(nodes, *target.NodeName)
 						}
+					case "Node":
+						nodes = append(nodes, target.TargetRef.Name)
+					}
+				}
+			}
 		default:
 			return nil, fmt.Errorf("object is not an endpointslice")
 		}

docs/configuration/configuration.md

@@ -134,6 +134,10 @@ job_name: <job_name>
 # Per-scrape timeout when scraping this job.
 [ scrape_timeout: <duration> | default = <global_config.scrape_timeout> ]
 
+# Whether to scrape a classic histogram that is also exposed as a native
+# histogram (has no effect without --enable-feature=native-histograms).
+[ scrape_classic_histograms: <boolean> | default = false ]
+
 # The HTTP resource path on which to fetch metrics from targets.
 [ metrics_path: <path> | default = /metrics ]
 
@@ -376,6 +380,11 @@ metric_relabel_configs:
 # 0 means no limit. This is an experimental feature, this behaviour could
 # change in the future.
 [ target_limit: <int> | default = 0 ]
+
+# Limit on total number of positive and negative buckets allowed in a single
+# native histogram. If this is exceeded, the entire scrape will be treated as
+# failed. 0 means no limit.
+[ native_histogram_bucket_limit: <int> | default = 0 ]
 ```
 
 Where `<job_name>` must be unique across all scrape configurations.
@@ -576,6 +585,8 @@ The following meta labels are available on targets during [relabeling](#relabel_
 # The information to access the Consul API. It is to be defined
 # as the Consul documentation requires.
 [ server: <host> | default = "localhost:8500" ]
+# Prefix for URIs for when consul is behind an API gateway (reverse proxy).
+[ path_prefix: <string> ]
 [ token: <secret> ]
 [ datacenter: <string> ]
 # Namespaces are only supported in Consul Enterprise.

docs/getting_started.md

@@ -264,4 +264,4 @@ process ID.
 While Prometheus does have recovery mechanisms in the case that there is an
 abrupt process failure it is recommend to use the `SIGTERM` signal to cleanly
 shutdown a Prometheus instance. If you're running on Linux this can be performed
-by using `kill -s SIGHUP <PID>`, replacing `<PID>` with your Prometheus process ID.
+by using `kill -s SIGTERM <PID>`, replacing `<PID>` with your Prometheus process ID.

docs/querying/api.md

@@ -1074,6 +1074,10 @@ The following endpoint returns various cardinality statistics about the Promethe
 ```
 GET /api/v1/status/tsdb
 ```
+URL query parameters:
+- `limit=<number>`: Limit the number of returned items to a given number for each set of statistics. By default, 10 items are returned.
+
+The `data` section of the query result consists of
 - **headStats**: This provides the following data about the head block of the TSDB:
   - **numSeries**: The number of series.
   - **chunkCount**: The number of chunks.

docs/querying/functions.md

@@ -589,8 +589,9 @@ over time and return an instant vector with per-series aggregation results:
 Note that all values in the specified interval have the same weight in the
 aggregation even if the values are not equally spaced throughout the interval.
 
-`count_over_time`, `last_over_time`, and `present_over_time` handle native
+`avg_over_time`, `sum_over_time`, `count_over_time`, `last_over_time`, and
-histograms as expected. All other functions ignore histogram samples.
+`present_over_time` handle native histograms as expected. All other functions
+ignore histogram samples.
 
 ## Trigonometric Functions
 

docs/querying/operators.md

@@ -318,19 +318,23 @@ histograms is still very limited.
 Logical/set binary operators work as expected even if histogram samples are
 involved. They only check for the existence of a vector element and don't
 change their behavior depending on the sample type of an element (float or
-histogram).
+histogram). The `count` aggregation operator works similarly.
 
-The binary `+` operator between two native histograms and the `sum` aggregation
+The binary `+` and `-` operators between two native histograms and the `sum`
-operator to aggregate native histograms are fully supported. Even if the
+and `avg` aggregation operators to aggregate native histograms are fully
-histograms involved have different bucket layouts, the buckets are
+supported. Even if the histograms involved have different bucket layouts, the
-automatically converted appropriately so that the operation can be
+buckets are automatically converted appropriately so that the operation can be
 performed. (With the currently supported bucket schemas, that's always
-possible.) If either operator has to sum up a mix of histogram samples and
+possible.) If either operator has to aggregate a mix of histogram samples and
 float samples, the corresponding vector element is removed from the output
 vector entirely.
 
-All other operators do not behave in a meaningful way. They either treat the
+The binary `*` operator works between a native histogram and a float in any
-histogram sample as if it were a float sample of value 0, or (in case of
+order, while the binary `/` operator can be used between a native histogram
-arithmetic operations between a scalar and a vector) they leave the histogram
+and a float in that exact order.
-sample unchanged. This behavior will change to a meaningful one before native
+
-histograms are a stable feature.
+All other operators (and unmentioned cases for the above operators) do not
+behave in a meaningful way. They either treat the histogram sample as if it
+were a float sample of value 0, or (in case of arithmetic operations between a
+scalar and a vector) they leave the histogram sample unchanged. This behavior
+will change to a meaningful one before native histograms are a stable feature.

docs/stability.md

@@ -18,12 +18,13 @@ Things considered stable for 2.x:
 * Configuration file format (minus the service discovery remote read/write, see below)
 * Rule/alert file format
 * Console template syntax and semantics
+* Remote write sending, per the [1.0 specification](https://prometheus.io/docs/concepts/remote_write_spec/).
 
 Things considered unstable for 2.x:
 
 * Any feature listed as experimental or subject to change, including:
   * The [`holt_winters` PromQL function](https://github.com/prometheus/prometheus/issues/2458)
-  * Remote read, remote write and the remote read endpoint
+  * Remote write receiving, remote read and the remote read endpoint
 * Server-side HTTPS and basic authentication
 * Service discovery integrations, with the exception of `static_configs` and `file_sd_configs`
 * Go APIs of packages that are part of the server

documentation/examples/remote_storage/go.mod

@@ -8,7 +8,7 @@ require (
 	github.com/gogo/protobuf v1.3.2
 	github.com/golang/snappy v0.0.4
 	github.com/influxdata/influxdb v1.11.0
-	github.com/prometheus/client_golang v1.14.0
+	github.com/prometheus/client_golang v1.15.0
 	github.com/prometheus/common v0.42.0
 	github.com/prometheus/prometheus v0.43.0
 	github.com/stretchr/testify v1.8.2
@@ -29,7 +29,7 @@ require (
 	github.com/grafana/regexp v0.0.0-20221122212121-6b5c0a4cb7fd // indirect
 	github.com/jmespath/go-jmespath v0.4.0 // indirect
 	github.com/jpillora/backoff v1.0.0 // indirect
-	github.com/kr/pretty v0.3.0 // indirect
+	github.com/kr/text v0.2.0 // indirect
 	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
 	github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f // indirect
 	github.com/pkg/errors v0.9.1 // indirect
@@ -51,7 +51,7 @@ require (
 	golang.org/x/text v0.8.0 // indirect
 	golang.org/x/time v0.3.0 // indirect
 	google.golang.org/appengine v1.6.7 // indirect
-	google.golang.org/protobuf v1.29.0 // indirect
+	google.golang.org/protobuf v1.30.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

documentation/examples/remote_storage/go.sum

@@ -141,8 +141,7 @@ github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxv
 github.com/konsorten/go-windows-terminal-sequences v1.0.3/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFBFZlji/RkVcI2GknAs/DXo4wKdlNEc=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
-github.com/kr/pretty v0.3.0 h1:WgNl7dwNpEZ6jJ9k1snq4pZsg7DOEN8hP9Xw0Tsjwk0=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
-github.com/kr/pretty v0.3.0/go.mod h1:640gp4NfQd8pI5XOwp5fnNeVWj67G7CFk/SaSQn7NBk=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
@@ -181,8 +180,8 @@ github.com/prometheus/client_golang v0.9.1/go.mod h1:7SWBe2y4D6OKWSNQJUaRYU/AaXP
 github.com/prometheus/client_golang v1.0.0/go.mod h1:db9x61etRT2tGnBNRi70OPL5FsnadC4Ky3P0J6CfImo=
 github.com/prometheus/client_golang v1.7.1/go.mod h1:PY5Wy2awLA44sXw4AOSfFBetzPP4j5+D6mVACh+pe2M=
 github.com/prometheus/client_golang v1.11.0/go.mod h1:Z6t4BnS23TR94PD6BsDNk8yVqroYurpAkEiz0P2BEV0=
-github.com/prometheus/client_golang v1.14.0 h1:nJdhIvne2eSX/XRAFV9PcvFFRbrjbcTUj0VP62TMhnw=
+github.com/prometheus/client_golang v1.15.0 h1:5fCgGYogn0hFdhyhLbw7hEsWxufKtY9klyvdNfFlFhM=
-github.com/prometheus/client_golang v1.14.0/go.mod h1:8vpkKitgIVNcqrRBWh1C4TIUQgYNtG/XQE4E/Zae36Y=
+github.com/prometheus/client_golang v1.15.0/go.mod h1:e9yaBhRPU2pPNsZwE+JdQl0KEt1N9XgF6zxWmaC0xOk=
 github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
 github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
 github.com/prometheus/client_model v0.2.0/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
@@ -204,7 +203,6 @@ github.com/prometheus/procfs v0.9.0 h1:wzCHvIvM5SxWqYvwgVL7yJY8Lz3PKn49KQtpgMYJf
 github.com/prometheus/procfs v0.9.0/go.mod h1:+pB4zwohETzFnmlpe6yd2lSc+0/46IYZRB/chUwxUZY=
 github.com/prometheus/prometheus v0.43.0 h1:18iCSfrbAHbXvYFvR38U1Pt4uZmU9SmDcCpCrBKUiGg=
 github.com/prometheus/prometheus v0.43.0/go.mod h1:2BA14LgBeqlPuzObSEbh+Y+JwLH2GcqDlJKbF2sA6FM=
-github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
 github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
 github.com/scaleway/scaleway-sdk-go v1.0.0-beta.14 h1:yFl3jyaSVLNYXlnNYM5z2pagEk1dYQhfr1p20T1NyKY=
 github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
@@ -341,14 +339,12 @@ google.golang.org/protobuf v1.21.0/go.mod h1:47Nbq4nVaFHyn7ilMalzfO3qCViNmqZ2kzi
 google.golang.org/protobuf v1.23.0/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2l/sGQquU=
 google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
 google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
-google.golang.org/protobuf v1.29.0 h1:44S3JjaKmLEE4YIkjzexaP+NzZsudE3Zin5Njn/pYX0=
+google.golang.org/protobuf v1.30.0 h1:kPPoIgf3TsEvrm0PFe15JQ+570QVxYzEvvHqChK+cng=
-google.golang.org/protobuf v1.29.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
+google.golang.org/protobuf v1.30.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
-gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
 gopkg.in/inf.v0 v0.9.1 h1:73M5CoZyi3ZLMOyDlQh031Cx6N9NDJ2Vvfl76EDAgDc=
 gopkg.in/ini.v1 v1.67.0 h1:Dgnx+6+nfE+IfzjUEISNeydPJh9AXNNsWbGP9KzCsOA=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

go.mod

@@ -13,7 +13,7 @@ require (
 	github.com/cespare/xxhash/v2 v2.2.0
 	github.com/dennwc/varint v1.0.0
 	github.com/dgraph-io/ristretto v0.1.1
-	github.com/digitalocean/godo v1.98.0
+	github.com/digitalocean/godo v1.99.0
 	github.com/docker/docker v23.0.4+incompatible
 	github.com/edsrzf/mmap-go v1.1.0
 	github.com/envoyproxy/go-control-plane v0.11.0
@@ -31,7 +31,7 @@ require (
 	github.com/grpc-ecosystem/grpc-gateway v1.16.0
 	github.com/hashicorp/consul/api v1.20.0
 	github.com/hashicorp/nomad/api v0.0.0-20230418003350-3067191c5197
-	github.com/hetznercloud/hcloud-go v1.42.0
+	github.com/hetznercloud/hcloud-go v1.45.1
 	github.com/ionos-cloud/sdk-go/v6 v6.1.6
 	github.com/json-iterator/go v1.1.12
 	github.com/kolo/xmlrpc v0.0.0-20220921171641-a4b6fa1dd06b
@@ -43,7 +43,7 @@ require (
 	github.com/ovh/go-ovh v1.4.1
 	github.com/pkg/errors v0.9.1
 	github.com/prometheus/alertmanager v0.25.0
-	github.com/prometheus/client_golang v1.15.0
+	github.com/prometheus/client_golang v1.15.1
 	github.com/prometheus/client_model v0.3.0
 	github.com/prometheus/common v0.42.0
 	github.com/prometheus/common/assets v0.2.0

go.sum

@@ -155,8 +155,8 @@ github.com/dgraph-io/ristretto v0.1.1/go.mod h1:S1GPSBCYCIhmVNfcth17y2zZtQT6wzkz
 github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
 github.com/dgryski/go-farm v0.0.0-20190423205320-6a90982ecee2 h1:tdlZCpZ/P9DhczCTSixgIKmwPv6+wP5DGjqLYw5SUiA=
 github.com/dgryski/go-farm v0.0.0-20190423205320-6a90982ecee2/go.mod h1:SqUrOPUnsFjfmXRMNPybcSiG0BgUW2AuFH8PAnS2iTw=
-github.com/digitalocean/godo v1.98.0 h1:potyC1eD0N9n5/P4/WmJuKgg+OGYZOBWEW+/aKTX6QQ=
+github.com/digitalocean/godo v1.99.0 h1:gUHO7n9bDaZFWvbzOum4bXE0/09ZuYA9yA8idQHX57E=
-github.com/digitalocean/godo v1.98.0/go.mod h1:NRpFznZFvhHjBoqZAaOD3khVzsJ3EibzKqFL4R60dmA=
+github.com/digitalocean/godo v1.99.0/go.mod h1:SsS2oXo2rznfM/nORlZ/6JaUJZFhmKTib1YhopUc8NA=
 github.com/dnaeon/go-vcr v1.2.0 h1:zHCHvJYTMh1N7xnV7zf1m1GPBF9Ad0Jk/whtQ1663qI=
 github.com/docker/distribution v2.8.1+incompatible h1:Q50tZOPR6T/hjNsyc9g8/syEs6bk8XXApsHjKukMl68=
 github.com/docker/distribution v2.8.1+incompatible/go.mod h1:J2gT2udsDAN96Uj4KfcMRqY0/ypR+oyYUYmja8H+y+w=
@@ -464,8 +464,8 @@ github.com/hashicorp/nomad/api v0.0.0-20230418003350-3067191c5197/go.mod h1:2TCr
 github.com/hashicorp/serf v0.8.2/go.mod h1:6hOLApaqBFA1NXqRQAsxw9QxuDEvNxSQRwA/JwenrHc=
 github.com/hashicorp/serf v0.10.1 h1:Z1H2J60yRKvfDYAOZLd2MU0ND4AH/WDz7xYHDWQsIPY=
 github.com/hashicorp/serf v0.10.1/go.mod h1:yL2t6BqATOLGc5HF7qbFkTfXoPIY0WZdWHfEvMqbG+4=
-github.com/hetznercloud/hcloud-go v1.42.0 h1:Es/CDOForQN3nOOP5Vxh1N/YHjpCg386iYEX5zCgi+A=
+github.com/hetznercloud/hcloud-go v1.45.1 h1:nl0OOklFfQT5J6AaNIOhl5Ruh3fhmGmhvZEqHbibVuk=
-github.com/hetznercloud/hcloud-go v1.42.0/go.mod h1:YADL8AbmQYH0Eo+1lkuyoc8LutT0UeMvaKP47nNUb+Y=
+github.com/hetznercloud/hcloud-go v1.45.1/go.mod h1:aAUGxSfSnB8/lVXHNEDxtCT1jykaul8kqjD7f5KQXF8=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/hudl/fargo v1.3.0/go.mod h1:y3CKSmjA+wD2gak7sUSXTAoopbhU08POFhmITJgmKTg=
 github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
@@ -655,8 +655,8 @@ github.com/prometheus/client_golang v1.3.0/go.mod h1:hJaj2vgQTGQmVCsAACORcieXFeD
 github.com/prometheus/client_golang v1.4.0/go.mod h1:e9GMxYsXl05ICDXkRhurwBS4Q3OK1iX/F2sw+iXX5zU=
 github.com/prometheus/client_golang v1.7.1/go.mod h1:PY5Wy2awLA44sXw4AOSfFBetzPP4j5+D6mVACh+pe2M=
 github.com/prometheus/client_golang v1.11.0/go.mod h1:Z6t4BnS23TR94PD6BsDNk8yVqroYurpAkEiz0P2BEV0=
-github.com/prometheus/client_golang v1.15.0 h1:5fCgGYogn0hFdhyhLbw7hEsWxufKtY9klyvdNfFlFhM=
+github.com/prometheus/client_golang v1.15.1 h1:8tXpTmJbyH5lydzFPoxSIJ0J46jdh3tylbvM1xCv0LI=
-github.com/prometheus/client_golang v1.15.0/go.mod h1:e9yaBhRPU2pPNsZwE+JdQl0KEt1N9XgF6zxWmaC0xOk=
+github.com/prometheus/client_golang v1.15.1/go.mod h1:e9yaBhRPU2pPNsZwE+JdQl0KEt1N9XgF6zxWmaC0xOk=
 github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
 github.com/prometheus/client_model v0.0.0-20190115171406-56726106282f/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
 github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=

model/histogram/float_histogram.go

@@ -159,12 +159,12 @@ func (h *FloatHistogram) ZeroBucket() Bucket[float64] {
 	}
 }
 
-// Scale scales the FloatHistogram by the provided factor, i.e. it scales all
+// Mul multiplies the FloatHistogram by the provided factor, i.e. it scales all
 // bucket counts including the zero bucket and the count and the sum of
 // observations. The bucket layout stays the same. This method changes the
 // receiving histogram directly (rather than acting on a copy). It returns a
 // pointer to the receiving histogram for convenience.
-func (h *FloatHistogram) Scale(factor float64) *FloatHistogram {
+func (h *FloatHistogram) Mul(factor float64) *FloatHistogram {
 	h.ZeroCount *= factor
 	h.Count *= factor
 	h.Sum *= factor
@@ -177,6 +177,21 @@ func (h *FloatHistogram) Scale(factor float64) *FloatHistogram {
 	return h
 }
 
+// Div works like Scale but divides instead of multiplies.
+// When dividing by 0, everything will be set to Inf.
+func (h *FloatHistogram) Div(scalar float64) *FloatHistogram {
+	h.ZeroCount /= scalar
+	h.Count /= scalar
+	h.Sum /= scalar
+	for i := range h.PositiveBuckets {
+		h.PositiveBuckets[i] /= scalar
+	}
+	for i := range h.NegativeBuckets {
+		h.NegativeBuckets[i] /= scalar
+	}
+	return h
+}
+
 // Add adds the provided other histogram to the receiving histogram. Count, Sum,
 // and buckets from the other histogram are added to the corresponding
 // components of the receiving histogram. Buckets in the other histogram that do

model/histogram/float_histogram_test.go

@@ -15,12 +15,13 @@ package histogram
 
 import (
 	"fmt"
+	"math"
 	"testing"
 
 	"github.com/stretchr/testify/require"
 )
 
-func TestFloatHistogramScale(t *testing.T) {
+func TestFloatHistogramMul(t *testing.T) {
 	cases := []struct {
 		name     string
 		in       *FloatHistogram
@@ -33,6 +34,30 @@ func TestFloatHistogramScale(t *testing.T) {
 			3.1415,
 			&FloatHistogram{},
 		},
+		{
+			"zero multiplier",
+			&FloatHistogram{
+				ZeroThreshold:   0.01,
+				ZeroCount:       5.5,
+				Count:           3493.3,
+				Sum:             2349209.324,
+				PositiveSpans:   []Span{{-2, 1}, {2, 3}},
+				PositiveBuckets: []float64{1, 3.3, 4.2, 0.1},
+				NegativeSpans:   []Span{{3, 2}, {3, 2}},
+				NegativeBuckets: []float64{3.1, 3, 1.234e5, 1000},
+			},
+			0,
+			&FloatHistogram{
+				ZeroThreshold:   0.01,
+				ZeroCount:       0,
+				Count:           0,
+				Sum:             0,
+				PositiveSpans:   []Span{{-2, 1}, {2, 3}},
+				PositiveBuckets: []float64{0, 0, 0, 0},
+				NegativeSpans:   []Span{{3, 2}, {3, 2}},
+				NegativeBuckets: []float64{0, 0, 0, 0},
+			},
+		},
 		{
 			"no-op",
 			&FloatHistogram{
@@ -81,17 +106,137 @@ func TestFloatHistogramScale(t *testing.T) {
 				NegativeBuckets: []float64{6.2, 6, 1.234e5 * 2, 2000},
 			},
 		},
+		{
+			"triple",
+			&FloatHistogram{
+				ZeroThreshold:   0.01,
+				ZeroCount:       11,
+				Count:           30,
+				Sum:             23,
+				PositiveSpans:   []Span{{-2, 2}, {1, 3}},
+				PositiveBuckets: []float64{1, 0, 3, 4, 7},
+				NegativeSpans:   []Span{{3, 2}, {3, 2}},
+				NegativeBuckets: []float64{3, 1, 5, 6},
+			},
+			3,
+			&FloatHistogram{
+				ZeroThreshold:   0.01,
+				ZeroCount:       33,
+				Count:           90,
+				Sum:             69,
+				PositiveSpans:   []Span{{-2, 2}, {1, 3}},
+				PositiveBuckets: []float64{3, 0, 9, 12, 21},
+				NegativeSpans:   []Span{{3, 2}, {3, 2}},
+				NegativeBuckets: []float64{9, 3, 15, 18},
+			},
+		},
 	}
 
 	for _, c := range cases {
 		t.Run(c.name, func(t *testing.T) {
-			require.Equal(t, c.expected, c.in.Scale(c.scale))
+			require.Equal(t, c.expected, c.in.Mul(c.scale))
 			// Has it also happened in-place?
 			require.Equal(t, c.expected, c.in)
 		})
 	}
 }
 
+func TestFloatHistogramDiv(t *testing.T) {
+	cases := []struct {
+		name     string
+		fh       *FloatHistogram
+		s        float64
+		expected *FloatHistogram
+	}{
+		{
+			"zero value",
+			&FloatHistogram{},
+			3.1415,
+			&FloatHistogram{},
+		},
+		{
+			"zero divisor",
+			&FloatHistogram{
+				ZeroThreshold:   0.01,
+				ZeroCount:       5.5,
+				Count:           3493.3,
+				Sum:             2349209.324,
+				PositiveSpans:   []Span{{-2, 1}, {2, 3}},
+				PositiveBuckets: []float64{1, 3.3, 4.2, 0.1},
+				NegativeSpans:   []Span{{3, 2}, {3, 2}},
+				NegativeBuckets: []float64{3.1, 3, 1.234e5, 1000},
+			},
+			0,
+			&FloatHistogram{
+				ZeroThreshold:   0.01,
+				ZeroCount:       math.Inf(1),
+				Count:           math.Inf(1),
+				Sum:             math.Inf(1),
+				PositiveSpans:   []Span{{-2, 1}, {2, 3}},
+				PositiveBuckets: []float64{math.Inf(1), math.Inf(1), math.Inf(1), math.Inf(1)},
+				NegativeSpans:   []Span{{3, 2}, {3, 2}},
+				NegativeBuckets: []float64{math.Inf(1), math.Inf(1), math.Inf(1), math.Inf(1)},
+			},
+		},
+		{
+			"no-op",
+			&FloatHistogram{
+				ZeroThreshold:   0.01,
+				ZeroCount:       5.5,
+				Count:           3493.3,
+				Sum:             2349209.324,
+				PositiveSpans:   []Span{{-2, 1}, {2, 3}},
+				PositiveBuckets: []float64{1, 3.3, 4.2, 0.1},
+				NegativeSpans:   []Span{{3, 2}, {3, 2}},
+				NegativeBuckets: []float64{3.1, 3, 1.234e5, 1000},
+			},
+			1,
+			&FloatHistogram{
+				ZeroThreshold:   0.01,
+				ZeroCount:       5.5,
+				Count:           3493.3,
+				Sum:             2349209.324,
+				PositiveSpans:   []Span{{-2, 1}, {2, 3}},
+				PositiveBuckets: []float64{1, 3.3, 4.2, 0.1},
+				NegativeSpans:   []Span{{3, 2}, {3, 2}},
+				NegativeBuckets: []float64{3.1, 3, 1.234e5, 1000},
+			},
+		},
+		{
+			"half",
+			&FloatHistogram{
+				ZeroThreshold:   0.01,
+				ZeroCount:       11,
+				Count:           30,
+				Sum:             23,
+				PositiveSpans:   []Span{{-2, 2}, {1, 3}},
+				PositiveBuckets: []float64{1, 0, 3, 4, 7},
+				NegativeSpans:   []Span{{3, 2}, {3, 2}},
+				NegativeBuckets: []float64{3, 1, 5, 6},
+			},
+			2,
+			&FloatHistogram{
+				ZeroThreshold:   0.01,
+				ZeroCount:       5.5,
+				Count:           15,
+				Sum:             11.5,
+				PositiveSpans:   []Span{{-2, 2}, {1, 3}},
+				PositiveBuckets: []float64{0.5, 0, 1.5, 2, 3.5},
+				NegativeSpans:   []Span{{3, 2}, {3, 2}},
+				NegativeBuckets: []float64{1.5, 0.5, 2.5, 3},
+			},
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			require.Equal(t, c.expected, c.fh.Div(c.s))
+			// Has it also happened in-place?
+			require.Equal(t, c.expected, c.fh)
+		})
+	}
+}
+
 func TestFloatHistogramDetectReset(t *testing.T) {
 	cases := []struct {
 		name              string

model/labels/labels.go

@@ -533,16 +533,15 @@ func (b *Builder) Set(n, v string) *Builder {
 }
 
 func (b *Builder) Get(n string) string {
-	for _, d := range b.del {
+	// Del() removes entries from .add but Set() does not remove from .del, so check .add first.
-		if d == n {
-			return ""
-		}
-	}
 	for _, a := range b.add {
 		if a.Name == n {
 			return a.Value
 		}
 	}
+	if slices.Contains(b.del, n) {
+		return ""
+	}
 	return b.base.Get(n)
 }
 

model/labels/labels_string.go

@@ -593,14 +593,15 @@ func (b *Builder) Set(n, v string) *Builder {
 }
 
 func (b *Builder) Get(n string) string {
-	if slices.Contains(b.del, n) {
+	// Del() removes entries from .add but Set() does not remove from .del, so check .add first.
-		return ""
-	}
 	for _, a := range b.add {
 		if a.Name == n {
 			return a.Value
 		}
 	}
+	if slices.Contains(b.del, n) {
+		return ""
+	}
 	return b.base.Get(n)
 }
 

model/labels/labels_test.go

@@ -607,6 +607,13 @@ func TestBuilder(t *testing.T) {
 			require.Equal(t, tcase.want.BytesWithoutLabels(nil, "aaa", "bbb"), b.Labels().Bytes(nil))
 		})
 	}
+	t.Run("set_after_del", func(t *testing.T) {
+		b := NewBuilder(FromStrings("aaa", "111"))
+		b.Del("bbb")
+		b.Set("bbb", "222")
+		require.Equal(t, FromStrings("aaa", "111", "bbb", "222"), b.Labels())
+		require.Equal(t, "222", b.Get("bbb"))
+	})
 }
 
 func TestScratchBuilder(t *testing.T) {

model/relabel/relabel_test.go

@@ -397,6 +397,34 @@ func TestRelabel(t *testing.T) {
 				"foo":              "bar",
 			}),
 		},
+		{ // From https://github.com/prometheus/prometheus/issues/12283
+			input: labels.FromMap(map[string]string{
+				"__meta_kubernetes_pod_container_port_name":         "foo",
+				"__meta_kubernetes_pod_annotation_XXX_metrics_port": "9091",
+			}),
+			relabel: []*Config{
+				{
+					Regex:  MustNewRegexp("^__meta_kubernetes_pod_container_port_name$"),
+					Action: LabelDrop,
+				},
+				{
+					SourceLabels: model.LabelNames{"__meta_kubernetes_pod_annotation_XXX_metrics_port"},
+					Regex:        MustNewRegexp("(.+)"),
+					Action:       Replace,
+					Replacement:  "metrics",
+					TargetLabel:  "__meta_kubernetes_pod_container_port_name",
+				},
+				{
+					SourceLabels: model.LabelNames{"__meta_kubernetes_pod_container_port_name"},
+					Regex:        MustNewRegexp("^metrics$"),
+					Action:       Keep,
+				},
+			},
+			output: labels.FromMap(map[string]string{
+				"__meta_kubernetes_pod_annotation_XXX_metrics_port": "9091",
+				"__meta_kubernetes_pod_container_port_name":         "metrics",
+			}),
+		},
 		{
 			input: labels.FromMap(map[string]string{
 				"a":  "foo",

model/textparse/interface.go

@@ -71,7 +71,7 @@ type Parser interface {
 //
 // This function always returns a valid parser, but might additionally
 // return an error if the content type cannot be parsed.
-func New(b []byte, contentType string) (Parser, error) {
+func New(b []byte, contentType string, parseClassicHistograms bool) (Parser, error) {
 	if contentType == "" {
 		return NewPromParser(b), nil
 	}
@@ -84,7 +84,7 @@ func New(b []byte, contentType string) (Parser, error) {
 	case "application/openmetrics-text":
 		return NewOpenMetricsParser(b), nil
 	case "application/vnd.google.protobuf":
-		return NewProtobufParser(b), nil
+		return NewProtobufParser(b, parseClassicHistograms), nil
 	default:
 		return NewPromParser(b), nil
 	}
@@ -100,7 +100,7 @@ const (
 	EntrySeries    Entry = 2 // A series with a simple float64 as value.
 	EntryComment   Entry = 3
 	EntryUnit      Entry = 4
-	EntryHistogram Entry = 5 // A series with a sparse histogram as a value.
+	EntryHistogram Entry = 5 // A series with a native histogram as a value.
 )
 
 // MetricType represents metric type values.

model/textparse/interface_test.go

@@ -91,7 +91,7 @@ func TestNewParser(t *testing.T) {
 			tt := tt // Copy to local variable before going parallel.
 			t.Parallel()
 
-			p, err := New([]byte{}, tt.contentType)
+			p, err := New([]byte{}, tt.contentType, false)
 			tt.validateParser(t, p)
 			if tt.err == "" {
 				require.NoError(t, err)

model/textparse/protobufparse.go

@@ -54,6 +54,8 @@ type ProtobufParser struct {
 	// quantiles/buckets.
 	fieldPos    int
 	fieldsDone  bool // true if no more fields of a Summary or (legacy) Histogram to be processed.
+	redoClassic bool // true after parsing a native histogram if we need to parse it again as a classit histogram.
+
 	// state is marked by the entry we are processing. EntryInvalid implies
 	// that we have to decode the next MetricFamily.
 	state Entry
@@ -62,17 +64,22 @@ type ProtobufParser struct {
 
 	mf *dto.MetricFamily
 
+	// Wether to also parse a classic histogram that is also present as a
+	// native histogram.
+	parseClassicHistograms bool
+
 	// The following are just shenanigans to satisfy the Parser interface.
 	metricBytes *bytes.Buffer // A somewhat fluid representation of the current metric.
 }
 
 // NewProtobufParser returns a parser for the payload in the byte slice.
-func NewProtobufParser(b []byte) Parser {
+func NewProtobufParser(b []byte, parseClassicHistograms bool) Parser {
 	return &ProtobufParser{
 		in:                     b,
 		state:                  EntryInvalid,
 		mf:                     &dto.MetricFamily{},
 		metricBytes:            &bytes.Buffer{},
+		parseClassicHistograms: parseClassicHistograms,
 	}
 }
 
@@ -106,21 +113,30 @@ func (p *ProtobufParser) Series() ([]byte, *int64, float64) {
 			v = s.GetQuantile()[p.fieldPos].GetValue()
 		}
 	case dto.MetricType_HISTOGRAM, dto.MetricType_GAUGE_HISTOGRAM:
-		// This should only happen for a legacy histogram.
+		// This should only happen for a classic histogram.
 		h := m.GetHistogram()
 		switch p.fieldPos {
 		case -2:
+			v = h.GetSampleCountFloat()
+			if v == 0 {
 				v = float64(h.GetSampleCount())
+			}
 		case -1:
 			v = h.GetSampleSum()
 		default:
 			bb := h.GetBucket()
 			if p.fieldPos >= len(bb) {
+				v = h.GetSampleCountFloat()
+				if v == 0 {
 					v = float64(h.GetSampleCount())
+				}
 			} else {
+				v = bb[p.fieldPos].GetCumulativeCountFloat()
+				if v == 0 {
 					v = float64(bb[p.fieldPos].GetCumulativeCount())
 				}
 			}
+		}
 	default:
 		panic("encountered unexpected metric type, this is a bug")
 	}
@@ -149,6 +165,9 @@ func (p *ProtobufParser) Histogram() ([]byte, *int64, *histogram.Histogram, *his
 		ts = m.GetTimestampMs()
 		h  = m.GetHistogram()
 	)
+	if p.parseClassicHistograms && len(h.GetBucket()) > 0 {
+		p.redoClassic = true
+	}
 	if h.GetSampleCountFloat() > 0 || h.GetZeroCountFloat() > 0 {
 		// It is a float histogram.
 		fh := histogram.FloatHistogram{
@@ -376,6 +395,12 @@ func (p *ProtobufParser) Next() (Entry, error) {
 			return EntryInvalid, err
 		}
 	case EntryHistogram, EntrySeries:
+		if p.redoClassic {
+			p.redoClassic = false
+			p.state = EntrySeries
+			p.fieldPos = -3
+			p.fieldsDone = false
+		}
 		t := p.mf.GetType()
 		if p.state == EntrySeries && !p.fieldsDone &&
 			(t == dto.MetricType_SUMMARY ||
@@ -432,7 +457,7 @@ func (p *ProtobufParser) updateMetricBytes() error {
 // state.
 func (p *ProtobufParser) getMagicName() string {
 	t := p.mf.GetType()
-	if p.state == EntryHistogram || (t != dto.MetricType_HISTOGRAM && t != dto.MetricType_SUMMARY) {
+	if p.state == EntryHistogram || (t != dto.MetricType_HISTOGRAM && t != dto.MetricType_GAUGE_HISTOGRAM && t != dto.MetricType_SUMMARY) {
 		return p.mf.GetName()
 	}
 	if p.fieldPos == -2 {

model/textparse/protobufparse_test.go

@@ -30,8 +30,8 @@ import (
 	dto "github.com/prometheus/prometheus/prompb/io/prometheus/client"
 )
 
-func TestProtobufParse(t *testing.T) {
+func createTestProtoBuf(t *testing.T) *bytes.Buffer {
-	textMetricFamilies := []string{
+	testMetricFamilies := []string{
 		`name: "go_build_info"
 help: "Build information about the main Go module."
 type: GAUGE
@@ -231,7 +231,6 @@ help: "Test float histogram with many buckets removed to keep it manageable in s
 type: HISTOGRAM
 metric: <
   histogram: <
-    sample_count: 175
     sample_count_float: 175.0
     sample_sum: 0.0008280461746287094
     bucket: <
@@ -302,7 +301,6 @@ help: "Like test_float_histogram but as gauge histogram."
 type: GAUGE_HISTOGRAM
 metric: <
   histogram: <
-    sample_count: 175
     sample_count_float: 175.0
     sample_sum: 0.0008280461746287094
     bucket: <
@@ -450,9 +448,9 @@ metric: <
 	}
 
 	varintBuf := make([]byte, binary.MaxVarintLen32)
-	inputBuf := &bytes.Buffer{}
+	buf := &bytes.Buffer{}
 
-	for _, tmf := range textMetricFamilies {
+	for _, tmf := range testMetricFamilies {
 		pb := &dto.MetricFamily{}
 		// From text to proto message.
 		require.NoError(t, proto.UnmarshalText(tmf, pb))
@@ -462,11 +460,15 @@ metric: <
 
 		// Write first length, then binary protobuf.
 		varintLength := binary.PutUvarint(varintBuf, uint64(len(protoBuf)))
-		inputBuf.Write(varintBuf[:varintLength])
+		buf.Write(varintBuf[:varintLength])
-		inputBuf.Write(protoBuf)
+		buf.Write(protoBuf)
 	}
 
-	exp := []struct {
+	return buf
+}
+
+func TestProtobufParse(t *testing.T) {
+	type parseResult struct {
 		lset    labels.Labels
 		m       string
 		t       int64
@@ -478,7 +480,19 @@ metric: <
 		shs     *histogram.Histogram
 		fhs     *histogram.FloatHistogram
 		e       []exemplar.Exemplar
+	}
+
+	inputBuf := createTestProtoBuf(t)
+
+	scenarios := []struct {
+		name     string
+		parser   Parser
+		expected []parseResult
 	}{
+		{
+			name:   "ignore classic buckets of native histograms",
+			parser: NewProtobufParser(inputBuf.Bytes(), false),
+			expected: []parseResult{
 				{
 					m:    "go_build_info",
 					help: "Build information about the main Go module.",
@@ -810,12 +824,587 @@ metric: <
 						"__name__", "without_quantiles_sum",
 					),
 				},
+			},
+		},
+		{
+			name:   "parse classic and native buckets",
+			parser: NewProtobufParser(inputBuf.Bytes(), true),
+			expected: []parseResult{
+				{ // 0
+					m:    "go_build_info",
+					help: "Build information about the main Go module.",
+				},
+				{ // 1
+					m:   "go_build_info",
+					typ: MetricTypeGauge,
+				},
+				{ // 2
+					m: "go_build_info\xFFchecksum\xFF\xFFpath\xFFgithub.com/prometheus/client_golang\xFFversion\xFF(devel)",
+					v: 1,
+					lset: labels.FromStrings(
+						"__name__", "go_build_info",
+						"checksum", "",
+						"path", "github.com/prometheus/client_golang",
+						"version", "(devel)",
+					),
+				},
+				{ // 3
+					m:    "go_memstats_alloc_bytes_total",
+					help: "Total number of bytes allocated, even if freed.",
+				},
+				{ // 4
+					m:   "go_memstats_alloc_bytes_total",
+					typ: MetricTypeCounter,
+				},
+				{ // 5
+					m: "go_memstats_alloc_bytes_total",
+					v: 1.546544e+06,
+					lset: labels.FromStrings(
+						"__name__", "go_memstats_alloc_bytes_total",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "42"), Value: 12, HasTs: true, Ts: 1625851151233},
+					},
+				},
+				{ // 6
+					m:    "something_untyped",
+					help: "Just to test the untyped type.",
+				},
+				{ // 7
+					m:   "something_untyped",
+					typ: MetricTypeUnknown,
+				},
+				{ // 8
+					m: "something_untyped",
+					t: 1234567,
+					v: 42,
+					lset: labels.FromStrings(
+						"__name__", "something_untyped",
+					),
+				},
+				{ // 9
+					m:    "test_histogram",
+					help: "Test histogram with many buckets removed to keep it manageable in size.",
+				},
+				{ // 10
+					m:   "test_histogram",
+					typ: MetricTypeHistogram,
+				},
+				{ // 11
+					m: "test_histogram",
+					t: 1234568,
+					shs: &histogram.Histogram{
+						Count:         175,
+						ZeroCount:     2,
+						Sum:           0.0008280461746287094,
+						ZeroThreshold: 2.938735877055719e-39,
+						Schema:        3,
+						PositiveSpans: []histogram.Span{
+							{Offset: -161, Length: 1},
+							{Offset: 8, Length: 3},
+						},
+						NegativeSpans: []histogram.Span{
+							{Offset: -162, Length: 1},
+							{Offset: 23, Length: 4},
+						},
+						PositiveBuckets: []int64{1, 2, -1, -1},
+						NegativeBuckets: []int64{1, 3, -2, -1, 1},
+					},
+					lset: labels.FromStrings(
+						"__name__", "test_histogram",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "59727"), Value: -0.00039, HasTs: true, Ts: 1625851155146},
+						{Labels: labels.FromStrings("dummyID", "5617"), Value: -0.00029, HasTs: false},
+					},
+				},
+				{ // 12
+					m: "test_histogram_count",
+					t: 1234568,
+					v: 175,
+					lset: labels.FromStrings(
+						"__name__", "test_histogram_count",
+					),
+				},
+				{ // 13
+					m: "test_histogram_sum",
+					t: 1234568,
+					v: 0.0008280461746287094,
+					lset: labels.FromStrings(
+						"__name__", "test_histogram_sum",
+					),
+				},
+				{ // 14
+					m: "test_histogram_bucket\xffle\xff-0.0004899999999999998",
+					t: 1234568,
+					v: 2,
+					lset: labels.FromStrings(
+						"__name__", "test_histogram_bucket",
+						"le", "-0.0004899999999999998",
+					),
+				},
+				{ // 15
+					m: "test_histogram_bucket\xffle\xff-0.0003899999999999998",
+					t: 1234568,
+					v: 4,
+					lset: labels.FromStrings(
+						"__name__", "test_histogram_bucket",
+						"le", "-0.0003899999999999998",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "59727"), Value: -0.00039, HasTs: true, Ts: 1625851155146},
+					},
+				},
+				{ // 16
+					m: "test_histogram_bucket\xffle\xff-0.0002899999999999998",
+					t: 1234568,
+					v: 16,
+					lset: labels.FromStrings(
+						"__name__", "test_histogram_bucket",
+						"le", "-0.0002899999999999998",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "5617"), Value: -0.00029, HasTs: false},
+					},
+				},
+				{ // 17
+					m: "test_histogram_bucket\xffle\xff+Inf",
+					t: 1234568,
+					v: 175,
+					lset: labels.FromStrings(
+						"__name__", "test_histogram_bucket",
+						"le", "+Inf",
+					),
+				},
+				{ // 18
+					m:    "test_gauge_histogram",
+					help: "Like test_histogram but as gauge histogram.",
+				},
+				{ // 19
+					m:   "test_gauge_histogram",
+					typ: MetricTypeGaugeHistogram,
+				},
+				{ // 20
+					m: "test_gauge_histogram",
+					t: 1234568,
+					shs: &histogram.Histogram{
+						CounterResetHint: histogram.GaugeType,
+						Count:            175,
+						ZeroCount:        2,
+						Sum:              0.0008280461746287094,
+						ZeroThreshold:    2.938735877055719e-39,
+						Schema:           3,
+						PositiveSpans: []histogram.Span{
+							{Offset: -161, Length: 1},
+							{Offset: 8, Length: 3},
+						},
+						NegativeSpans: []histogram.Span{
+							{Offset: -162, Length: 1},
+							{Offset: 23, Length: 4},
+						},
+						PositiveBuckets: []int64{1, 2, -1, -1},
+						NegativeBuckets: []int64{1, 3, -2, -1, 1},
+					},
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_histogram",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "59727"), Value: -0.00039, HasTs: true, Ts: 1625851155146},
+						{Labels: labels.FromStrings("dummyID", "5617"), Value: -0.00029, HasTs: false},
+					},
+				},
+				{ // 21
+					m: "test_gauge_histogram_count",
+					t: 1234568,
+					v: 175,
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_histogram_count",
+					),
+				},
+				{ // 22
+					m: "test_gauge_histogram_sum",
+					t: 1234568,
+					v: 0.0008280461746287094,
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_histogram_sum",
+					),
+				},
+				{ // 23
+					m: "test_gauge_histogram_bucket\xffle\xff-0.0004899999999999998",
+					t: 1234568,
+					v: 2,
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_histogram_bucket",
+						"le", "-0.0004899999999999998",
+					),
+				},
+				{ // 24
+					m: "test_gauge_histogram_bucket\xffle\xff-0.0003899999999999998",
+					t: 1234568,
+					v: 4,
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_histogram_bucket",
+						"le", "-0.0003899999999999998",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "59727"), Value: -0.00039, HasTs: true, Ts: 1625851155146},
+					},
+				},
+				{ // 25
+					m: "test_gauge_histogram_bucket\xffle\xff-0.0002899999999999998",
+					t: 1234568,
+					v: 16,
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_histogram_bucket",
+						"le", "-0.0002899999999999998",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "5617"), Value: -0.00029, HasTs: false},
+					},
+				},
+				{ // 26
+					m: "test_gauge_histogram_bucket\xffle\xff+Inf",
+					t: 1234568,
+					v: 175,
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_histogram_bucket",
+						"le", "+Inf",
+					),
+				},
+				{ // 27
+					m:    "test_float_histogram",
+					help: "Test float histogram with many buckets removed to keep it manageable in size.",
+				},
+				{ // 28
+					m:   "test_float_histogram",
+					typ: MetricTypeHistogram,
+				},
+				{ // 29
+					m: "test_float_histogram",
+					t: 1234568,
+					fhs: &histogram.FloatHistogram{
+						Count:         175.0,
+						ZeroCount:     2.0,
+						Sum:           0.0008280461746287094,
+						ZeroThreshold: 2.938735877055719e-39,
+						Schema:        3,
+						PositiveSpans: []histogram.Span{
+							{Offset: -161, Length: 1},
+							{Offset: 8, Length: 3},
+						},
+						NegativeSpans: []histogram.Span{
+							{Offset: -162, Length: 1},
+							{Offset: 23, Length: 4},
+						},
+						PositiveBuckets: []float64{1.0, 2.0, -1.0, -1.0},
+						NegativeBuckets: []float64{1.0, 3.0, -2.0, -1.0, 1.0},
+					},
+					lset: labels.FromStrings(
+						"__name__", "test_float_histogram",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "59727"), Value: -0.00039, HasTs: true, Ts: 1625851155146},
+						{Labels: labels.FromStrings("dummyID", "5617"), Value: -0.00029, HasTs: false},
+					},
+				},
+				{ // 30
+					m: "test_float_histogram_count",
+					t: 1234568,
+					v: 175,
+					lset: labels.FromStrings(
+						"__name__", "test_float_histogram_count",
+					),
+				},
+				{ // 31
+					m: "test_float_histogram_sum",
+					t: 1234568,
+					v: 0.0008280461746287094,
+					lset: labels.FromStrings(
+						"__name__", "test_float_histogram_sum",
+					),
+				},
+				{ // 32
+					m: "test_float_histogram_bucket\xffle\xff-0.0004899999999999998",
+					t: 1234568,
+					v: 2,
+					lset: labels.FromStrings(
+						"__name__", "test_float_histogram_bucket",
+						"le", "-0.0004899999999999998",
+					),
+				},
+				{ // 33
+					m: "test_float_histogram_bucket\xffle\xff-0.0003899999999999998",
+					t: 1234568,
+					v: 4,
+					lset: labels.FromStrings(
+						"__name__", "test_float_histogram_bucket",
+						"le", "-0.0003899999999999998",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "59727"), Value: -0.00039, HasTs: true, Ts: 1625851155146},
+					},
+				},
+				{ // 34
+					m: "test_float_histogram_bucket\xffle\xff-0.0002899999999999998",
+					t: 1234568,
+					v: 16,
+					lset: labels.FromStrings(
+						"__name__", "test_float_histogram_bucket",
+						"le", "-0.0002899999999999998",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "5617"), Value: -0.00029, HasTs: false},
+					},
+				},
+				{ // 35
+					m: "test_float_histogram_bucket\xffle\xff+Inf",
+					t: 1234568,
+					v: 175,
+					lset: labels.FromStrings(
+						"__name__", "test_float_histogram_bucket",
+						"le", "+Inf",
+					),
+				},
+				{ // 36
+					m:    "test_gauge_float_histogram",
+					help: "Like test_float_histogram but as gauge histogram.",
+				},
+				{ // 37
+					m:   "test_gauge_float_histogram",
+					typ: MetricTypeGaugeHistogram,
+				},
+				{ // 38
+					m: "test_gauge_float_histogram",
+					t: 1234568,
+					fhs: &histogram.FloatHistogram{
+						CounterResetHint: histogram.GaugeType,
+						Count:            175.0,
+						ZeroCount:        2.0,
+						Sum:              0.0008280461746287094,
+						ZeroThreshold:    2.938735877055719e-39,
+						Schema:           3,
+						PositiveSpans: []histogram.Span{
+							{Offset: -161, Length: 1},
+							{Offset: 8, Length: 3},
+						},
+						NegativeSpans: []histogram.Span{
+							{Offset: -162, Length: 1},
+							{Offset: 23, Length: 4},
+						},
+						PositiveBuckets: []float64{1.0, 2.0, -1.0, -1.0},
+						NegativeBuckets: []float64{1.0, 3.0, -2.0, -1.0, 1.0},
+					},
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_float_histogram",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "59727"), Value: -0.00039, HasTs: true, Ts: 1625851155146},
+						{Labels: labels.FromStrings("dummyID", "5617"), Value: -0.00029, HasTs: false},
+					},
+				},
+				{ // 39
+					m: "test_gauge_float_histogram_count",
+					t: 1234568,
+					v: 175,
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_float_histogram_count",
+					),
+				},
+				{ // 40
+					m: "test_gauge_float_histogram_sum",
+					t: 1234568,
+					v: 0.0008280461746287094,
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_float_histogram_sum",
+					),
+				},
+				{ // 41
+					m: "test_gauge_float_histogram_bucket\xffle\xff-0.0004899999999999998",
+					t: 1234568,
+					v: 2,
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_float_histogram_bucket",
+						"le", "-0.0004899999999999998",
+					),
+				},
+				{ // 42
+					m: "test_gauge_float_histogram_bucket\xffle\xff-0.0003899999999999998",
+					t: 1234568,
+					v: 4,
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_float_histogram_bucket",
+						"le", "-0.0003899999999999998",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "59727"), Value: -0.00039, HasTs: true, Ts: 1625851155146},
+					},
+				},
+				{ // 43
+					m: "test_gauge_float_histogram_bucket\xffle\xff-0.0002899999999999998",
+					t: 1234568,
+					v: 16,
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_float_histogram_bucket",
+						"le", "-0.0002899999999999998",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "5617"), Value: -0.00029, HasTs: false},
+					},
+				},
+				{ // 44
+					m: "test_gauge_float_histogram_bucket\xffle\xff+Inf",
+					t: 1234568,
+					v: 175,
+					lset: labels.FromStrings(
+						"__name__", "test_gauge_float_histogram_bucket",
+						"le", "+Inf",
+					),
+				},
+				{ // 45
+					m:    "test_histogram2",
+					help: "Similar histogram as before but now without sparse buckets.",
+				},
+				{ // 46
+					m:   "test_histogram2",
+					typ: MetricTypeHistogram,
+				},
+				{ // 47
+					m: "test_histogram2_count",
+					v: 175,
+					lset: labels.FromStrings(
+						"__name__", "test_histogram2_count",
+					),
+				},
+				{ // 48
+					m: "test_histogram2_sum",
+					v: 0.000828,
+					lset: labels.FromStrings(
+						"__name__", "test_histogram2_sum",
+					),
+				},
+				{ // 49
+					m: "test_histogram2_bucket\xffle\xff-0.00048",
+					v: 2,
+					lset: labels.FromStrings(
+						"__name__", "test_histogram2_bucket",
+						"le", "-0.00048",
+					),
+				},
+				{ // 50
+					m: "test_histogram2_bucket\xffle\xff-0.00038",
+					v: 4,
+					lset: labels.FromStrings(
+						"__name__", "test_histogram2_bucket",
+						"le", "-0.00038",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "59727"), Value: -0.00038, HasTs: true, Ts: 1625851153146},
+					},
+				},
+				{ // 51
+					m: "test_histogram2_bucket\xffle\xff1.0",
+					v: 16,
+					lset: labels.FromStrings(
+						"__name__", "test_histogram2_bucket",
+						"le", "1.0",
+					),
+					e: []exemplar.Exemplar{
+						{Labels: labels.FromStrings("dummyID", "5617"), Value: -0.000295, HasTs: false},
+					},
+				},
+				{ // 52
+					m: "test_histogram2_bucket\xffle\xff+Inf",
+					v: 175,
+					lset: labels.FromStrings(
+						"__name__", "test_histogram2_bucket",
+						"le", "+Inf",
+					),
+				},
+				{ // 53
+					m:    "rpc_durations_seconds",
+					help: "RPC latency distributions.",
+				},
+				{ // 54
+					m:   "rpc_durations_seconds",
+					typ: MetricTypeSummary,
+				},
+				{ // 55
+					m: "rpc_durations_seconds_count\xffservice\xffexponential",
+					v: 262,
+					lset: labels.FromStrings(
+						"__name__", "rpc_durations_seconds_count",
+						"service", "exponential",
+					),
+				},
+				{ // 56
+					m: "rpc_durations_seconds_sum\xffservice\xffexponential",
+					v: 0.00025551262820703587,
+					lset: labels.FromStrings(
+						"__name__", "rpc_durations_seconds_sum",
+						"service", "exponential",
+					),
+				},
+				{ // 57
+					m: "rpc_durations_seconds\xffservice\xffexponential\xffquantile\xff0.5",
+					v: 6.442786329648548e-07,
+					lset: labels.FromStrings(
+						"__name__", "rpc_durations_seconds",
+						"quantile", "0.5",
+						"service", "exponential",
+					),
+				},
+				{ // 58
+					m: "rpc_durations_seconds\xffservice\xffexponential\xffquantile\xff0.9",
+					v: 1.9435742936658396e-06,
+					lset: labels.FromStrings(
+						"__name__", "rpc_durations_seconds",
+						"quantile", "0.9",
+						"service", "exponential",
+					),
+				},
+				{ // 59
+					m: "rpc_durations_seconds\xffservice\xffexponential\xffquantile\xff0.99",
+					v: 4.0471608667037015e-06,
+					lset: labels.FromStrings(
+						"__name__", "rpc_durations_seconds",
+						"quantile", "0.99",
+						"service", "exponential",
+					),
+				},
+				{ // 60
+					m:    "without_quantiles",
+					help: "A summary without quantiles.",
+				},
+				{ // 61
+					m:   "without_quantiles",
+					typ: MetricTypeSummary,
+				},
+				{ // 62
+					m: "without_quantiles_count",
+					v: 42,
+					lset: labels.FromStrings(
+						"__name__", "without_quantiles_count",
+					),
+				},
+				{ // 63
+					m: "without_quantiles_sum",
+					v: 1.234,
+					lset: labels.FromStrings(
+						"__name__", "without_quantiles_sum",
+					),
+				},
+			},
+		},
 	}
 
-	p := NewProtobufParser(inputBuf.Bytes())
+	for _, scenario := range scenarios {
-	i := 0
+		t.Run(scenario.name, func(t *testing.T) {
-
+			var (
-	var res labels.Labels
+				i   int
+				res labels.Labels
+				p   = scenario.parser
+				exp = scenario.expected
+			)
 
 			for {
 				et, err := p.Next()
@@ -891,4 +1480,6 @@ metric: <
 				i++
 			}
 			require.Equal(t, len(exp), i)
+		})
+	}
 }

promql/engine.go

@@ -1850,14 +1850,14 @@ func (ev *evaluator) vectorSelectorSingle(it *storage.MemoizedSeriesIterator, no
 		}
 	case chunkenc.ValFloat:
 		t, v = it.At()
-	case chunkenc.ValHistogram, chunkenc.ValFloatHistogram:
+	case chunkenc.ValFloatHistogram:
 		t, h = it.AtFloatHistogram()
 	default:
 		panic(fmt.Errorf("unknown value type %v", valueType))
 	}
 	if valueType == chunkenc.ValNone || t > refTime {
 		var ok bool
-		t, v, _, h, ok = it.PeekPrev()
+		t, v, h, ok = it.PeekPrev()
 		if !ok || t < refTime-durationMilliseconds(ev.lookbackDelta) {
 			return 0, 0, nil, false
 		}
@@ -2263,15 +2263,12 @@ func (ev *evaluator) VectorBinop(op parser.ItemType, lhs, rhs Vector, matching *
 			insertedSigs[insertSig] = struct{}{}
 		}
 
-		if (hl != nil && hr != nil) || (hl == nil && hr == nil) {
-			// Both lhs and rhs are of same type.
 		enh.Out = append(enh.Out, Sample{
 			Metric: metric,
 			F:      floatValue,
 			H:      histogramValue,
 		})
 	}
-	}
 	return enh.Out
 }
 
@@ -2337,28 +2334,33 @@ func resultMetric(lhs, rhs labels.Labels, op parser.ItemType, matching *parser.V
 // VectorscalarBinop evaluates a binary operation between a Vector and a Scalar.
 func (ev *evaluator) VectorscalarBinop(op parser.ItemType, lhs Vector, rhs Scalar, swap, returnBool bool, enh *EvalNodeHelper) Vector {
 	for _, lhsSample := range lhs {
-		lv, rv := lhsSample.F, rhs.V
+		lf, rf := lhsSample.F, rhs.V
+		var rh *histogram.FloatHistogram
+		lh := lhsSample.H
 		// lhs always contains the Vector. If the original position was different
 		// swap for calculating the value.
 		if swap {
-			lv, rv = rv, lv
+			lf, rf = rf, lf
+			lh, rh = rh, lh
 		}
-		value, _, keep := vectorElemBinop(op, lv, rv, nil, nil)
+		float, histogram, keep := vectorElemBinop(op, lf, rf, lh, rh)
 		// Catch cases where the scalar is the LHS in a scalar-vector comparison operation.
 		// We want to always keep the vector element value as the output value, even if it's on the RHS.
 		if op.IsComparisonOperator() && swap {
-			value = rv
+			float = rf
+			histogram = rh
 		}
 		if returnBool {
 			if keep {
-				value = 1.0
+				float = 1.0
 			} else {
-				value = 0.0
+				float = 0.0
 			}
 			keep = true
 		}
 		if keep {
-			lhsSample.F = value
+			lhsSample.F = float
+			lhsSample.H = histogram
 			if shouldDropMetricName(op) || returnBool {
 				lhsSample.Metric = enh.DropMetricName(lhsSample.Metric)
 			}
@@ -2413,16 +2415,33 @@ func vectorElemBinop(op parser.ItemType, lhs, rhs float64, hlhs, hrhs *histogram
 			// The histogram being added must have the larger schema
 			// code (i.e. the higher resolution).
 			if hrhs.Schema >= hlhs.Schema {
-				return 0, hlhs.Copy().Add(hrhs), true
+				return 0, hlhs.Copy().Add(hrhs).Compact(0), true
 			}
-			return 0, hrhs.Copy().Add(hlhs), true
+			return 0, hrhs.Copy().Add(hlhs).Compact(0), true
 		}
 		return lhs + rhs, nil, true
 	case parser.SUB:
+		if hlhs != nil && hrhs != nil {
+			// The histogram being subtracted must have the larger schema
+			// code (i.e. the higher resolution).
+			if hrhs.Schema >= hlhs.Schema {
+				return 0, hlhs.Copy().Sub(hrhs).Compact(0), true
+			}
+			return 0, hrhs.Copy().Mul(-1).Add(hlhs).Compact(0), true
+		}
 		return lhs - rhs, nil, true
 	case parser.MUL:
+		if hlhs != nil && hrhs == nil {
+			return 0, hlhs.Copy().Mul(rhs), true
+		}
+		if hlhs == nil && hrhs != nil {
+			return 0, hrhs.Copy().Mul(lhs), true
+		}
 		return lhs * rhs, nil, true
 	case parser.DIV:
+		if hlhs != nil && hrhs == nil {
+			return 0, hlhs.Copy().Div(rhs), true
+		}
 		return lhs / rhs, nil, true
 	case parser.POW:
 		return math.Pow(lhs, rhs), nil, true
@@ -2452,7 +2471,8 @@ type groupedAggregation struct {
 	labels         labels.Labels
 	floatValue     float64
 	histogramValue *histogram.FloatHistogram
-	mean           float64
+	floatMean      float64
+	histogramMean  *histogram.FloatHistogram
 	groupCount     int
 	heap           vectorByValueHeap
 	reverseHeap    vectorByReverseValueHeap
@@ -2536,7 +2556,7 @@ func (ev *evaluator) aggregation(op parser.ItemType, grouping []string, without
 			newAgg := &groupedAggregation{
 				labels:     m,
 				floatValue: s.F,
-				mean:       s.F,
+				floatMean:  s.F,
 				groupCount: 1,
 			}
 			switch {
@@ -2545,6 +2565,11 @@ func (ev *evaluator) aggregation(op parser.ItemType, grouping []string, without
 			case op == parser.SUM:
 				newAgg.histogramValue = s.H.Copy()
 				newAgg.hasHistogram = true
+			case op == parser.AVG:
+				newAgg.histogramMean = s.H.Copy()
+				newAgg.hasHistogram = true
+			case op == parser.STDVAR || op == parser.STDDEV:
+				newAgg.groupCount = 0
 			}
 
 			result[groupingKey] = newAgg
@@ -2589,9 +2614,7 @@ func (ev *evaluator) aggregation(op parser.ItemType, grouping []string, without
 					if s.H.Schema >= group.histogramValue.Schema {
 						group.histogramValue.Add(s.H)
 					} else {
-						h := s.H.Copy()
+						group.histogramValue = s.H.Copy().Add(group.histogramValue)
-						h.Add(group.histogramValue)
-						group.histogramValue = h
 					}
 				}
 				// Otherwise the aggregation contained floats
@@ -2604,10 +2627,30 @@ func (ev *evaluator) aggregation(op parser.ItemType, grouping []string, without
 
 		case parser.AVG:
 			group.groupCount++
-			if math.IsInf(group.mean, 0) {
+			if s.H != nil {
-				if math.IsInf(s.F, 0) && (group.mean > 0) == (s.F > 0) {
+				group.hasHistogram = true
-					// The `mean` and `s.V` values are `Inf` of the same sign.  They
+				if group.histogramMean != nil {
-					// can't be subtracted, but the value of `mean` is correct
+					left := s.H.Copy().Div(float64(group.groupCount))
+					right := group.histogramMean.Copy().Div(float64(group.groupCount))
+					// The histogram being added/subtracted must have
+					// an equal or larger schema.
+					if s.H.Schema >= group.histogramMean.Schema {
+						toAdd := right.Mul(-1).Add(left)
+						group.histogramMean.Add(toAdd)
+					} else {
+						toAdd := left.Sub(right)
+						group.histogramMean = toAdd.Add(group.histogramMean)
+					}
+				}
+				// Otherwise the aggregation contained floats
+				// previously and will be invalid anyway. No
+				// point in copying the histogram in that case.
+			} else {
+				group.hasFloat = true
+				if math.IsInf(group.floatMean, 0) {
+					if math.IsInf(s.F, 0) && (group.floatMean > 0) == (s.F > 0) {
+						// The `floatMean` and `s.F` values are `Inf` of the same sign.  They
+						// can't be subtracted, but the value of `floatMean` is correct
 						// already.
 						break
 					}
@@ -2622,7 +2665,8 @@ func (ev *evaluator) aggregation(op parser.ItemType, grouping []string, without
 					}
 				}
 				// Divide each side of the `-` by `group.groupCount` to avoid float64 overflows.
-			group.mean += s.F/float64(group.groupCount) - group.mean/float64(group.groupCount)
+				group.floatMean += s.F/float64(group.groupCount) - group.floatMean/float64(group.groupCount)
+			}
 
 		case parser.GROUP:
 			// Do nothing. Required to avoid the panic in `default:` below.
@@ -2641,10 +2685,12 @@ func (ev *evaluator) aggregation(op parser.ItemType, grouping []string, without
 			group.groupCount++
 
 		case parser.STDVAR, parser.STDDEV:
+			if s.H == nil { // Ignore native histograms.
 				group.groupCount++
-			delta := s.F - group.mean
+				delta := s.F - group.floatMean
-			group.mean += delta / float64(group.groupCount)
+				group.floatMean += delta / float64(group.groupCount)
-			group.floatValue += delta * (s.F - group.mean)
+				group.floatValue += delta * (s.F - group.floatMean)
+			}
 
 		case parser.TOPK:
 			// We build a heap of up to k elements, with the smallest element at heap[0].
@@ -2696,7 +2742,16 @@ func (ev *evaluator) aggregation(op parser.ItemType, grouping []string, without
 	for _, aggr := range orderedResult {
 		switch op {
 		case parser.AVG:
-			aggr.floatValue = aggr.mean
+			if aggr.hasFloat && aggr.hasHistogram {
+				// We cannot aggregate histogram sample with a float64 sample.
+				// TODO(zenador): Issue warning when plumbing is in place.
+				continue
+			}
+			if aggr.hasHistogram {
+				aggr.histogramValue = aggr.histogramMean.Compact(0)
+			} else {
+				aggr.floatValue = aggr.floatMean
+			}
 
 		case parser.COUNT, parser.COUNT_VALUES:
 			aggr.floatValue = float64(aggr.groupCount)
@@ -2739,8 +2794,12 @@ func (ev *evaluator) aggregation(op parser.ItemType, grouping []string, without
 		case parser.SUM:
 			if aggr.hasFloat && aggr.hasHistogram {
 				// We cannot aggregate histogram sample with a float64 sample.
+				// TODO(zenador): Issue warning when plumbing is in place.
 				continue
 			}
+			if aggr.hasHistogram {
+				aggr.histogramValue.Compact(0)
+			}
 		default:
 			// For other aggregations, we already have the right value.
 		}

promql/engine_test.go

@@ -3986,16 +3986,18 @@ func TestNativeHistogram_HistogramFraction(t *testing.T) {
 	}
 }
 
-func TestNativeHistogram_Sum_Count_AddOperator(t *testing.T) {
+func TestNativeHistogram_Sum_Count_Add_AvgOperator(t *testing.T) {
 	// TODO(codesome): Integrate histograms into the PromQL testing framework
 	// and write more tests there.
 	cases := []struct {
 		histograms  []histogram.Histogram
 		expected    histogram.FloatHistogram
+		expectedAvg histogram.FloatHistogram
 	}{
 		{
 			histograms: []histogram.Histogram{
 				{
+					CounterResetHint: histogram.GaugeType,
 					Schema:           0,
 					Count:            21,
 					Sum:              1234.5,
@@ -4012,6 +4014,182 @@ func TestNativeHistogram_Sum_Count_AddOperator(t *testing.T) {
 					},
 					NegativeBuckets: []int64{2, 2, -3, 8},
 				},
+				{
+					CounterResetHint: histogram.GaugeType,
+					Schema:           0,
+					Count:            36,
+					Sum:              2345.6,
+					ZeroThreshold:    0.001,
+					ZeroCount:        5,
+					PositiveSpans: []histogram.Span{
+						{Offset: 0, Length: 4},
+						{Offset: 0, Length: 0},
+						{Offset: 0, Length: 3},
+					},
+					PositiveBuckets: []int64{1, 2, -2, 1, -1, 0, 0},
+					NegativeSpans: []histogram.Span{
+						{Offset: 1, Length: 4},
+						{Offset: 2, Length: 0},
+						{Offset: 2, Length: 3},
+					},
+					NegativeBuckets: []int64{1, 3, -2, 5, -2, 0, -3},
+				},
+				{
+					CounterResetHint: histogram.GaugeType,
+					Schema:           0,
+					Count:            36,
+					Sum:              1111.1,
+					ZeroThreshold:    0.001,
+					ZeroCount:        5,
+					PositiveSpans: []histogram.Span{
+						{Offset: 0, Length: 4},
+						{Offset: 0, Length: 0},
+						{Offset: 0, Length: 3},
+					},
+					PositiveBuckets: []int64{1, 2, -2, 1, -1, 0, 0},
+					NegativeSpans: []histogram.Span{
+						{Offset: 1, Length: 4},
+						{Offset: 2, Length: 0},
+						{Offset: 2, Length: 3},
+					},
+					NegativeBuckets: []int64{1, 3, -2, 5, -2, 0, -3},
+				},
+				{
+					CounterResetHint: histogram.GaugeType,
+					Schema:           1, // Everything is 0 just to make the count 4 so avg has nicer numbers.
+				},
+			},
+			expected: histogram.FloatHistogram{
+				CounterResetHint: histogram.GaugeType,
+				Schema:           0,
+				ZeroThreshold:    0.001,
+				ZeroCount:        14,
+				Count:            93,
+				Sum:              4691.2,
+				PositiveSpans: []histogram.Span{
+					{Offset: 0, Length: 7},
+				},
+				PositiveBuckets: []float64{3, 8, 2, 5, 3, 2, 2},
+				NegativeSpans: []histogram.Span{
+					{Offset: 0, Length: 6},
+					{Offset: 3, Length: 3},
+				},
+				NegativeBuckets: []float64{2, 6, 8, 4, 15, 9, 10, 10, 4},
+			},
+			expectedAvg: histogram.FloatHistogram{
+				CounterResetHint: histogram.GaugeType,
+				Schema:           0,
+				ZeroThreshold:    0.001,
+				ZeroCount:        3.5,
+				Count:            23.25,
+				Sum:              1172.8,
+				PositiveSpans: []histogram.Span{
+					{Offset: 0, Length: 7},
+				},
+				PositiveBuckets: []float64{0.75, 2, 0.5, 1.25, 0.75, 0.5, 0.5},
+				NegativeSpans: []histogram.Span{
+					{Offset: 0, Length: 6},
+					{Offset: 3, Length: 3},
+				},
+				NegativeBuckets: []float64{0.5, 1.5, 2, 1, 3.75, 2.25, 2.5, 2.5, 1},
+			},
+		},
+	}
+
+	idx0 := int64(0)
+	for _, c := range cases {
+		for _, floatHisto := range []bool{true, false} {
+			t.Run(fmt.Sprintf("floatHistogram=%t %d", floatHisto, idx0), func(t *testing.T) {
+				test, err := NewTest(t, "")
+				require.NoError(t, err)
+				t.Cleanup(test.Close)
+
+				seriesName := "sparse_histogram_series"
+				seriesNameOverTime := "sparse_histogram_series_over_time"
+
+				engine := test.QueryEngine()
+
+				ts := idx0 * int64(10*time.Minute/time.Millisecond)
+				app := test.Storage().Appender(context.TODO())
+				for idx1, h := range c.histograms {
+					lbls := labels.FromStrings("__name__", seriesName, "idx", fmt.Sprintf("%d", idx1))
+					// Since we mutate h later, we need to create a copy here.
+					if floatHisto {
+						_, err = app.AppendHistogram(0, lbls, ts, nil, h.Copy().ToFloat())
+					} else {
+						_, err = app.AppendHistogram(0, lbls, ts, h.Copy(), nil)
+					}
+					require.NoError(t, err)
+
+					lbls = labels.FromStrings("__name__", seriesNameOverTime)
+					newTs := ts + int64(idx1)*int64(time.Minute/time.Millisecond)
+					// Since we mutate h later, we need to create a copy here.
+					if floatHisto {
+						_, err = app.AppendHistogram(0, lbls, newTs, nil, h.Copy().ToFloat())
+					} else {
+						_, err = app.AppendHistogram(0, lbls, newTs, h.Copy(), nil)
+					}
+					require.NoError(t, err)
+				}
+				require.NoError(t, app.Commit())
+
+				queryAndCheck := func(queryString string, ts int64, exp Vector) {
+					qry, err := engine.NewInstantQuery(test.context, test.Queryable(), nil, queryString, timestamp.Time(ts))
+					require.NoError(t, err)
+
+					res := qry.Exec(test.Context())
+					require.NoError(t, res.Err)
+
+					vector, err := res.Vector()
+					require.NoError(t, err)
+
+					require.Equal(t, exp, vector)
+				}
+
+				// sum().
+				queryString := fmt.Sprintf("sum(%s)", seriesName)
+				queryAndCheck(queryString, ts, []Sample{{T: ts, H: &c.expected, Metric: labels.EmptyLabels()}})
+
+				// + operator.
+				queryString = fmt.Sprintf(`%s{idx="0"}`, seriesName)
+				for idx := 1; idx < len(c.histograms); idx++ {
+					queryString += fmt.Sprintf(` + ignoring(idx) %s{idx="%d"}`, seriesName, idx)
+				}
+				queryAndCheck(queryString, ts, []Sample{{T: ts, H: &c.expected, Metric: labels.EmptyLabels()}})
+
+				// count().
+				queryString = fmt.Sprintf("count(%s)", seriesName)
+				queryAndCheck(queryString, ts, []Sample{{T: ts, F: 4, Metric: labels.EmptyLabels()}})
+
+				// avg().
+				queryString = fmt.Sprintf("avg(%s)", seriesName)
+				queryAndCheck(queryString, ts, []Sample{{T: ts, H: &c.expectedAvg, Metric: labels.EmptyLabels()}})
+
+				offset := int64(len(c.histograms) - 1)
+				newTs := ts + offset*int64(time.Minute/time.Millisecond)
+
+				// sum_over_time().
+				queryString = fmt.Sprintf("sum_over_time(%s[%dm:1m])", seriesNameOverTime, offset)
+				queryAndCheck(queryString, newTs, []Sample{{T: newTs, H: &c.expected, Metric: labels.EmptyLabels()}})
+
+				// avg_over_time().
+				queryString = fmt.Sprintf("avg_over_time(%s[%dm:1m])", seriesNameOverTime, offset)
+				queryAndCheck(queryString, newTs, []Sample{{T: newTs, H: &c.expectedAvg, Metric: labels.EmptyLabels()}})
+			})
+			idx0++
+		}
+	}
+}
+
+func TestNativeHistogram_SubOperator(t *testing.T) {
+	// TODO(codesome): Integrate histograms into the PromQL testing framework
+	// and write more tests there.
+	cases := []struct {
+		histograms []histogram.Histogram
+		expected   histogram.FloatHistogram
+	}{
+		{
+			histograms: []histogram.Histogram{
 				{
 					Schema:        0,
 					Count:         36,
@@ -4033,9 +4211,116 @@ func TestNativeHistogram_Sum_Count_AddOperator(t *testing.T) {
 				},
 				{
 					Schema:        0,
-					Count:         36,
+					Count:         11,
+					Sum:           1234.5,
+					ZeroThreshold: 0.001,
+					ZeroCount:     3,
+					PositiveSpans: []histogram.Span{
+						{Offset: 1, Length: 2},
+					},
+					PositiveBuckets: []int64{2, -1},
+					NegativeSpans: []histogram.Span{
+						{Offset: 2, Length: 2},
+					},
+					NegativeBuckets: []int64{3, -1},
+				},
+			},
+			expected: histogram.FloatHistogram{
+				Schema:        0,
+				Count:         25,
 				Sum:           1111.1,
 				ZeroThreshold: 0.001,
+				ZeroCount:     2,
+				PositiveSpans: []histogram.Span{
+					{Offset: 0, Length: 2},
+					{Offset: 1, Length: 4},
+				},
+				PositiveBuckets: []float64{1, 1, 2, 1, 1, 1},
+				NegativeSpans: []histogram.Span{
+					{Offset: 1, Length: 2},
+					{Offset: 1, Length: 1},
+					{Offset: 4, Length: 3},
+				},
+				NegativeBuckets: []float64{1, 1, 7, 5, 5, 2},
+			},
+		},
+		{
+			histograms: []histogram.Histogram{
+				{
+					Schema:        0,
+					Count:         36,
+					Sum:           2345.6,
+					ZeroThreshold: 0.001,
+					ZeroCount:     5,
+					PositiveSpans: []histogram.Span{
+						{Offset: 0, Length: 4},
+						{Offset: 0, Length: 0},
+						{Offset: 0, Length: 3},
+					},
+					PositiveBuckets: []int64{1, 2, -2, 1, -1, 0, 0},
+					NegativeSpans: []histogram.Span{
+						{Offset: 1, Length: 4},
+						{Offset: 2, Length: 0},
+						{Offset: 2, Length: 3},
+					},
+					NegativeBuckets: []int64{1, 3, -2, 5, -2, 0, -3},
+				},
+				{
+					Schema:        1,
+					Count:         11,
+					Sum:           1234.5,
+					ZeroThreshold: 0.001,
+					ZeroCount:     3,
+					PositiveSpans: []histogram.Span{
+						{Offset: 1, Length: 2},
+					},
+					PositiveBuckets: []int64{2, -1},
+					NegativeSpans: []histogram.Span{
+						{Offset: 2, Length: 2},
+					},
+					NegativeBuckets: []int64{3, -1},
+				},
+			},
+			expected: histogram.FloatHistogram{
+				Schema:        0,
+				Count:         25,
+				Sum:           1111.1,
+				ZeroThreshold: 0.001,
+				ZeroCount:     2,
+				PositiveSpans: []histogram.Span{
+					{Offset: 0, Length: 1},
+					{Offset: 1, Length: 5},
+				},
+				PositiveBuckets: []float64{1, 1, 2, 1, 1, 1},
+				NegativeSpans: []histogram.Span{
+					{Offset: 1, Length: 4},
+					{Offset: 4, Length: 3},
+				},
+				NegativeBuckets: []float64{-2, 2, 2, 7, 5, 5, 2},
+			},
+		},
+		{
+			histograms: []histogram.Histogram{
+				{
+					Schema:        1,
+					Count:         11,
+					Sum:           1234.5,
+					ZeroThreshold: 0.001,
+					ZeroCount:     3,
+					PositiveSpans: []histogram.Span{
+						{Offset: 1, Length: 2},
+					},
+					PositiveBuckets: []int64{2, -1},
+					NegativeSpans: []histogram.Span{
+						{Offset: 2, Length: 2},
+					},
+					NegativeBuckets: []int64{3, -1},
+				},
+				{
+					Schema:        0,
+					Count:         36,
+					Sum:           2345.6,
+					ZeroThreshold: 0.001,
 					ZeroCount:     5,
 					PositiveSpans: []histogram.Span{
 						{Offset: 0, Length: 4},
@@ -4053,21 +4338,20 @@ func TestNativeHistogram_Sum_Count_AddOperator(t *testing.T) {
 			},
 			expected: histogram.FloatHistogram{
 				Schema:        0,
+				Count:         -25,
+				Sum:           -1111.1,
 				ZeroThreshold: 0.001,
-				ZeroCount:     14,
+				ZeroCount:     -2,
-				Count:         93,
-				Sum:           4691.2,
 				PositiveSpans: []histogram.Span{
-					{Offset: 0, Length: 3},
+					{Offset: 0, Length: 1},
-					{Offset: 0, Length: 4},
+					{Offset: 1, Length: 5},
 				},
-				PositiveBuckets: []float64{3, 8, 2, 5, 3, 2, 2},
+				PositiveBuckets: []float64{-1, -1, -2, -1, -1, -1},
 				NegativeSpans: []histogram.Span{
-					{Offset: 0, Length: 4},
+					{Offset: 1, Length: 4},
-					{Offset: 0, Length: 2},
+					{Offset: 4, Length: 3},
-					{Offset: 3, Length: 3},
 				},
-				NegativeBuckets: []float64{2, 6, 8, 4, 15, 9, 10, 10, 4},
+				NegativeBuckets: []float64{2, -2, -2, -7, -5, -5, -2},
 			},
 		},
 	}
@@ -4111,20 +4395,177 @@ func TestNativeHistogram_Sum_Count_AddOperator(t *testing.T) {
 					require.Equal(t, exp, vector)
 				}
 
-				// sum().
+				// - operator.
-				queryString := fmt.Sprintf("sum(%s)", seriesName)
+				queryString := fmt.Sprintf(`%s{idx="0"}`, seriesName)
-				queryAndCheck(queryString, []Sample{{T: ts, H: &c.expected, Metric: labels.EmptyLabels()}})
-
-				// + operator.
-				queryString = fmt.Sprintf(`%s{idx="0"}`, seriesName)
 				for idx := 1; idx < len(c.histograms); idx++ {
-					queryString += fmt.Sprintf(` + ignoring(idx) %s{idx="%d"}`, seriesName, idx)
+					queryString += fmt.Sprintf(` - ignoring(idx) %s{idx="%d"}`, seriesName, idx)
 				}
 				queryAndCheck(queryString, []Sample{{T: ts, H: &c.expected, Metric: labels.EmptyLabels()}})
+			})
+			idx0++
+		}
+	}
+}
 
-				// count().
+func TestNativeHistogram_MulDivOperator(t *testing.T) {
-				queryString = fmt.Sprintf("count(%s)", seriesName)
+	// TODO(codesome): Integrate histograms into the PromQL testing framework
-				queryAndCheck(queryString, []Sample{{T: ts, F: 3, Metric: labels.EmptyLabels()}})
+	// and write more tests there.
+	originalHistogram := histogram.Histogram{
+		Schema:        0,
+		Count:         21,
+		Sum:           33,
+		ZeroThreshold: 0.001,
+		ZeroCount:     3,
+		PositiveSpans: []histogram.Span{
+			{Offset: 0, Length: 3},
+		},
+		PositiveBuckets: []int64{3, 0, 0},
+		NegativeSpans: []histogram.Span{
+			{Offset: 0, Length: 3},
+		},
+		NegativeBuckets: []int64{3, 0, 0},
+	}
+
+	cases := []struct {
+		scalar      float64
+		histogram   histogram.Histogram
+		expectedMul histogram.FloatHistogram
+		expectedDiv histogram.FloatHistogram
+	}{
+		{
+			scalar:    3,
+			histogram: originalHistogram,
+			expectedMul: histogram.FloatHistogram{
+				Schema:        0,
+				Count:         63,
+				Sum:           99,
+				ZeroThreshold: 0.001,
+				ZeroCount:     9,
+				PositiveSpans: []histogram.Span{
+					{Offset: 0, Length: 3},
+				},
+				PositiveBuckets: []float64{9, 9, 9},
+				NegativeSpans: []histogram.Span{
+					{Offset: 0, Length: 3},
+				},
+				NegativeBuckets: []float64{9, 9, 9},
+			},
+			expectedDiv: histogram.FloatHistogram{
+				Schema:        0,
+				Count:         7,
+				Sum:           11,
+				ZeroThreshold: 0.001,
+				ZeroCount:     1,
+				PositiveSpans: []histogram.Span{
+					{Offset: 0, Length: 3},
+				},
+				PositiveBuckets: []float64{1, 1, 1},
+				NegativeSpans: []histogram.Span{
+					{Offset: 0, Length: 3},
+				},
+				NegativeBuckets: []float64{1, 1, 1},
+			},
+		},
+		{
+			scalar:    0,
+			histogram: originalHistogram,
+			expectedMul: histogram.FloatHistogram{
+				Schema:        0,
+				Count:         0,
+				Sum:           0,
+				ZeroThreshold: 0.001,
+				ZeroCount:     0,
+				PositiveSpans: []histogram.Span{
+					{Offset: 0, Length: 3},
+				},
+				PositiveBuckets: []float64{0, 0, 0},
+				NegativeSpans: []histogram.Span{
+					{Offset: 0, Length: 3},
+				},
+				NegativeBuckets: []float64{0, 0, 0},
+			},
+			expectedDiv: histogram.FloatHistogram{
+				Schema:        0,
+				Count:         math.Inf(1),
+				Sum:           math.Inf(1),
+				ZeroThreshold: 0.001,
+				ZeroCount:     math.Inf(1),
+				PositiveSpans: []histogram.Span{
+					{Offset: 0, Length: 3},
+				},
+				PositiveBuckets: []float64{math.Inf(1), math.Inf(1), math.Inf(1)},
+				NegativeSpans: []histogram.Span{
+					{Offset: 0, Length: 3},
+				},
+				NegativeBuckets: []float64{math.Inf(1), math.Inf(1), math.Inf(1)},
+			},
+		},
+	}
+
+	idx0 := int64(0)
+	for _, c := range cases {
+		for _, floatHisto := range []bool{true, false} {
+			t.Run(fmt.Sprintf("floatHistogram=%t %d", floatHisto, idx0), func(t *testing.T) {
+				test, err := NewTest(t, "")
+				require.NoError(t, err)
+				t.Cleanup(test.Close)
+
+				seriesName := "sparse_histogram_series"
+				floatSeriesName := "float_series"
+
+				engine := test.QueryEngine()
+
+				ts := idx0 * int64(10*time.Minute/time.Millisecond)
+				app := test.Storage().Appender(context.TODO())
+				h := c.histogram
+				lbls := labels.FromStrings("__name__", seriesName)
+				// Since we mutate h later, we need to create a copy here.
+				if floatHisto {
+					_, err = app.AppendHistogram(0, lbls, ts, nil, h.Copy().ToFloat())
+				} else {
+					_, err = app.AppendHistogram(0, lbls, ts, h.Copy(), nil)
+				}
+				require.NoError(t, err)
+				_, err = app.Append(0, labels.FromStrings("__name__", floatSeriesName), ts, c.scalar)
+				require.NoError(t, err)
+				require.NoError(t, app.Commit())
+
+				queryAndCheck := func(queryString string, exp Vector) {
+					qry, err := engine.NewInstantQuery(test.context, test.Queryable(), nil, queryString, timestamp.Time(ts))
+					require.NoError(t, err)
+
+					res := qry.Exec(test.Context())
+					require.NoError(t, res.Err)
+
+					vector, err := res.Vector()
+					require.NoError(t, err)
+
+					require.Equal(t, exp, vector)
+				}
+
+				// histogram * scalar.
+				queryString := fmt.Sprintf(`%s * %f`, seriesName, c.scalar)
+				queryAndCheck(queryString, []Sample{{T: ts, H: &c.expectedMul, Metric: labels.EmptyLabels()}})
+
+				// scalar * histogram.
+				queryString = fmt.Sprintf(`%f * %s`, c.scalar, seriesName)
+				queryAndCheck(queryString, []Sample{{T: ts, H: &c.expectedMul, Metric: labels.EmptyLabels()}})
+
+				// histogram * float.
+				queryString = fmt.Sprintf(`%s * %s`, seriesName, floatSeriesName)
+				queryAndCheck(queryString, []Sample{{T: ts, H: &c.expectedMul, Metric: labels.EmptyLabels()}})
+
+				// float * histogram.
+				queryString = fmt.Sprintf(`%s * %s`, floatSeriesName, seriesName)
+				queryAndCheck(queryString, []Sample{{T: ts, H: &c.expectedMul, Metric: labels.EmptyLabels()}})
+
+				// histogram / scalar.
+				queryString = fmt.Sprintf(`%s / %f`, seriesName, c.scalar)
+				queryAndCheck(queryString, []Sample{{T: ts, H: &c.expectedDiv, Metric: labels.EmptyLabels()}})
+
+				// histogram / float.
+				queryString = fmt.Sprintf(`%s / %s`, seriesName, floatSeriesName)
+				queryAndCheck(queryString, []Sample{{T: ts, H: &c.expectedDiv, Metric: labels.EmptyLabels()}})
 			})
 			idx0++
 		}

promql/functions.go

@@ -162,7 +162,7 @@ func extrapolatedRate(vals []parser.Value, args parser.Expressions, enh *EvalNod
 	if resultHistogram == nil {
 		resultFloat *= factor
 	} else {
-		resultHistogram.Scale(factor)
+		resultHistogram.Mul(factor)
 	}
 
 	return append(enh.Out, Sample{F: resultFloat, H: resultHistogram})
@@ -443,15 +443,40 @@ func aggrOverTime(vals []parser.Value, enh *EvalNodeHelper, aggrFn func(Series)
 	return append(enh.Out, Sample{F: aggrFn(el)})
 }
 
+func aggrHistOverTime(vals []parser.Value, enh *EvalNodeHelper, aggrFn func(Series) *histogram.FloatHistogram) Vector {
+	el := vals[0].(Matrix)[0]
+
+	return append(enh.Out, Sample{H: aggrFn(el)})
+}
+
 // === avg_over_time(Matrix parser.ValueTypeMatrix) Vector ===
 func funcAvgOverTime(vals []parser.Value, args parser.Expressions, enh *EvalNodeHelper) Vector {
-	if len(vals[0].(Matrix)[0].Floats) == 0 {
+	if len(vals[0].(Matrix)[0].Floats) > 0 && len(vals[0].(Matrix)[0].Histograms) > 0 {
-		// TODO(beorn7): The passed values only contain
+		// TODO(zenador): Add warning for mixed floats and histograms.
-		// histograms. avg_over_time ignores histograms for now. If
-		// there are only histograms, we have to return without adding
-		// anything to enh.Out.
 		return enh.Out
 	}
+	if len(vals[0].(Matrix)[0].Floats) == 0 {
+		// The passed values only contain histograms.
+		return aggrHistOverTime(vals, enh, func(s Series) *histogram.FloatHistogram {
+			count := 1
+			mean := s.Histograms[0].H.Copy()
+			for _, h := range s.Histograms[1:] {
+				count++
+				left := h.H.Copy().Div(float64(count))
+				right := mean.Copy().Div(float64(count))
+				// The histogram being added/subtracted must have
+				// an equal or larger schema.
+				if h.H.Schema >= mean.Schema {
+					toAdd := right.Mul(-1).Add(left)
+					mean.Add(toAdd)
+				} else {
+					toAdd := left.Sub(right)
+					mean = toAdd.Add(mean)
+				}
+			}
+			return mean
+		})
+	}
 	return aggrOverTime(vals, enh, func(s Series) float64 {
 		var mean, count, c float64
 		for _, f := range s.Floats {
@@ -558,13 +583,26 @@ func funcMinOverTime(vals []parser.Value, args parser.Expressions, enh *EvalNode
 
 // === sum_over_time(Matrix parser.ValueTypeMatrix) Vector ===
 func funcSumOverTime(vals []parser.Value, args parser.Expressions, enh *EvalNodeHelper) Vector {
-	if len(vals[0].(Matrix)[0].Floats) == 0 {
+	if len(vals[0].(Matrix)[0].Floats) > 0 && len(vals[0].(Matrix)[0].Histograms) > 0 {
-		// TODO(beorn7): The passed values only contain
+		// TODO(zenador): Add warning for mixed floats and histograms.
-		// histograms. sum_over_time ignores histograms for now. If
-		// there are only histograms, we have to return without adding
-		// anything to enh.Out.
 		return enh.Out
 	}
+	if len(vals[0].(Matrix)[0].Floats) == 0 {
+		// The passed values only contain histograms.
+		return aggrHistOverTime(vals, enh, func(s Series) *histogram.FloatHistogram {
+			sum := s.Histograms[0].H.Copy()
+			for _, h := range s.Histograms[1:] {
+				// The histogram being added must have
+				// an equal or larger schema.
+				if h.H.Schema >= sum.Schema {
+					sum.Add(h.H)
+				} else {
+					sum = h.H.Copy().Add(sum)
+				}
+			}
+			return sum
+		})
+	}
 	return aggrOverTime(vals, enh, func(s Series) float64 {
 		var sum, c float64
 		for _, f := range s.Floats {

promql/fuzz.go

@@ -58,7 +58,7 @@ const (
 )
 
 func fuzzParseMetricWithContentType(in []byte, contentType string) int {
-	p, warning := textparse.New(in, contentType)
+	p, warning := textparse.New(in, contentType, false)
 	if warning != nil {
 		// An invalid content type is being passed, which should not happen
 		// in this context.

scrape/clientprotobuf.go

@@ -0,0 +1,54 @@
+// Copyright 2023 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package scrape
+
+import (
+	"bytes"
+	"encoding/binary"
+
+	"github.com/gogo/protobuf/proto"
+
+	// Intentionally using client model to simulate client in tests.
+	dto "github.com/prometheus/client_model/go"
+)
+
+// Write a MetricFamily into a protobuf.
+// This function is intended for testing scraping by providing protobuf serialized input.
+func MetricFamilyToProtobuf(metricFamily *dto.MetricFamily) ([]byte, error) {
+	buffer := &bytes.Buffer{}
+	err := AddMetricFamilyToProtobuf(buffer, metricFamily)
+	if err != nil {
+		return nil, err
+	}
+	return buffer.Bytes(), nil
+}
+
+// Append a MetricFamily protobuf representation to a buffer.
+// This function is intended for testing scraping by providing protobuf serialized input.
+func AddMetricFamilyToProtobuf(buffer *bytes.Buffer, metricFamily *dto.MetricFamily) error {
+	protoBuf, err := proto.Marshal(metricFamily)
+	if err != nil {
+		return err
+	}
+
+	varintBuf := make([]byte, binary.MaxVarintLen32)
+	varintLength := binary.PutUvarint(varintBuf, uint64(len(protoBuf)))
+
+	_, err = buffer.Write(varintBuf[:varintLength])
+	if err != nil {
+		return err
+	}
+	_, err = buffer.Write(protoBuf)
+	return err
+}

scrape/scrape.go

@@ -191,6 +191,12 @@ var (
 		},
 		[]string{"scrape_job"},
 	)
+	targetScrapeNativeHistogramBucketLimit = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "prometheus_target_scrapes_exceeded_native_histogram_bucket_limit_total",
+			Help: "Total number of scrapes that hit the native histogram bucket limit and were rejected.",
+		},
+	)
 )
 
 func init() {
@@ -216,6 +222,7 @@ func init() {
 		targetScrapeExemplarOutOfOrder,
 		targetScrapePoolExceededLabelLimits,
 		targetSyncFailed,
+		targetScrapeNativeHistogramBucketLimit,
 	)
 }
 
@@ -256,11 +263,13 @@ type scrapeLoopOptions struct {
 	target                  *Target
 	scraper                 scraper
 	sampleLimit             int
+	bucketLimit             int
 	labelLimits             *labelLimits
 	honorLabels             bool
 	honorTimestamps         bool
 	interval                time.Duration
 	timeout                 time.Duration
+	scrapeClassicHistograms bool
 	mrc                     []*relabel.Config
 	cache                   *scrapeCache
 }
@@ -319,9 +328,11 @@ func newScrapePool(cfg *config.ScrapeConfig, app storage.Appendable, jitterSeed
 			jitterSeed,
 			opts.honorTimestamps,
 			opts.sampleLimit,
+			opts.bucketLimit,
 			opts.labelLimits,
 			opts.interval,
 			opts.timeout,
+			opts.scrapeClassicHistograms,
 			options.ExtraMetrics,
 			options.EnableMetadataStorage,
 			opts.target,
@@ -412,6 +423,7 @@ func (sp *scrapePool) reload(cfg *config.ScrapeConfig) error {
 		timeout       = time.Duration(sp.config.ScrapeTimeout)
 		bodySizeLimit = int64(sp.config.BodySizeLimit)
 		sampleLimit   = int(sp.config.SampleLimit)
+		bucketLimit   = int(sp.config.NativeHistogramBucketLimit)
 		labelLimits   = &labelLimits{
 			labelLimit:            int(sp.config.LabelLimit),
 			labelNameLengthLimit:  int(sp.config.LabelNameLengthLimit),
@@ -446,6 +458,7 @@ func (sp *scrapePool) reload(cfg *config.ScrapeConfig) error {
 				target:          t,
 				scraper:         s,
 				sampleLimit:     sampleLimit,
+				bucketLimit:     bucketLimit,
 				labelLimits:     labelLimits,
 				honorLabels:     honorLabels,
 				honorTimestamps: honorTimestamps,
@@ -530,6 +543,7 @@ func (sp *scrapePool) sync(targets []*Target) {
 		timeout       = time.Duration(sp.config.ScrapeTimeout)
 		bodySizeLimit = int64(sp.config.BodySizeLimit)
 		sampleLimit   = int(sp.config.SampleLimit)
+		bucketLimit   = int(sp.config.NativeHistogramBucketLimit)
 		labelLimits   = &labelLimits{
 			labelLimit:            int(sp.config.LabelLimit),
 			labelNameLengthLimit:  int(sp.config.LabelNameLengthLimit),
@@ -538,6 +552,7 @@ func (sp *scrapePool) sync(targets []*Target) {
 		honorLabels             = sp.config.HonorLabels
 		honorTimestamps         = sp.config.HonorTimestamps
 		mrc                     = sp.config.MetricRelabelConfigs
+		scrapeClassicHistograms = sp.config.ScrapeClassicHistograms
 	)
 
 	sp.targetMtx.Lock()
@@ -559,12 +574,14 @@ func (sp *scrapePool) sync(targets []*Target) {
 				target:                  t,
 				scraper:                 s,
 				sampleLimit:             sampleLimit,
+				bucketLimit:             bucketLimit,
 				labelLimits:             labelLimits,
 				honorLabels:             honorLabels,
 				honorTimestamps:         honorTimestamps,
 				mrc:                     mrc,
 				interval:                interval,
 				timeout:                 timeout,
+				scrapeClassicHistograms: scrapeClassicHistograms,
 			})
 			if err != nil {
 				l.setForcedError(err)
@@ -731,17 +748,24 @@ func mutateReportSampleLabels(lset labels.Labels, target *Target) labels.Labels
 }
 
 // appender returns an appender for ingested samples from the target.
-func appender(app storage.Appender, limit int) storage.Appender {
+func appender(app storage.Appender, sampleLimit, bucketLimit int) storage.Appender {
 	app = &timeLimitAppender{
 		Appender: app,
 		maxTime:  timestamp.FromTime(time.Now().Add(maxAheadTime)),
 	}
 
-	// The limit is applied after metrics are potentially dropped via relabeling.
+	// The sampleLimit is applied after metrics are potentially dropped via relabeling.
-	if limit > 0 {
+	if sampleLimit > 0 {
 		app = &limitAppender{
 			Appender: app,
-			limit:    limit,
+			limit:    sampleLimit,
+		}
+	}
+
+	if bucketLimit > 0 {
+		app = &bucketLimitAppender{
+			Appender: app,
+			limit:    bucketLimit,
 		}
 	}
 	return app
@@ -872,9 +896,11 @@ type scrapeLoop struct {
 	forcedErr               error
 	forcedErrMtx            sync.Mutex
 	sampleLimit             int
+	bucketLimit             int
 	labelLimits             *labelLimits
 	interval                time.Duration
 	timeout                 time.Duration
+	scrapeClassicHistograms bool
 
 	appender            func(ctx context.Context) storage.Appender
 	sampleMutator       labelsMutator
@@ -1152,9 +1178,11 @@ func newScrapeLoop(ctx context.Context,
 	jitterSeed uint64,
 	honorTimestamps bool,
 	sampleLimit int,
+	bucketLimit int,
 	labelLimits *labelLimits,
 	interval time.Duration,
 	timeout time.Duration,
+	scrapeClassicHistograms bool,
 	reportExtraMetrics bool,
 	appendMetadataToWAL bool,
 	target *Target,
@@ -1195,9 +1223,11 @@ func newScrapeLoop(ctx context.Context,
 		appenderCtx:             appenderCtx,
 		honorTimestamps:         honorTimestamps,
 		sampleLimit:             sampleLimit,
+		bucketLimit:             bucketLimit,
 		labelLimits:             labelLimits,
 		interval:                interval,
 		timeout:                 timeout,
+		scrapeClassicHistograms: scrapeClassicHistograms,
 		reportExtraMetrics:      reportExtraMetrics,
 		appendMetadataToWAL:     appendMetadataToWAL,
 	}
@@ -1469,7 +1499,7 @@ type appendErrors struct {
 }
 
 func (sl *scrapeLoop) append(app storage.Appender, b []byte, contentType string, ts time.Time) (total, added, seriesAdded int, err error) {
-	p, err := textparse.New(b, contentType)
+	p, err := textparse.New(b, contentType, sl.scrapeClassicHistograms)
 	if err != nil {
 		level.Debug(sl.l).Log(
 			"msg", "Invalid content type on scrape, using prometheus parser as fallback.",
@@ -1482,6 +1512,7 @@ func (sl *scrapeLoop) append(app storage.Appender, b []byte, contentType string,
 		defTime         = timestamp.FromTime(ts)
 		appErrs         = appendErrors{}
 		sampleLimitErr  error
+		bucketLimitErr  error
 		e               exemplar.Exemplar // escapes to heap so hoisted out of loop
 		meta            metadata.Metadata
 		metadataChanged bool
@@ -1510,7 +1541,7 @@ func (sl *scrapeLoop) append(app storage.Appender, b []byte, contentType string,
 	}
 
 	// Take an appender with limits.
-	app = appender(app, sl.sampleLimit)
+	app = appender(app, sl.sampleLimit, sl.bucketLimit)
 
 	defer func() {
 		if err != nil {
@@ -1631,7 +1662,7 @@ loop:
 		} else {
 			ref, err = app.Append(ref, lset, t, val)
 		}
-		sampleAdded, err = sl.checkAddError(ce, met, parsedTimestamp, err, &sampleLimitErr, &appErrs)
+		sampleAdded, err = sl.checkAddError(ce, met, parsedTimestamp, err, &sampleLimitErr, &bucketLimitErr, &appErrs)
 		if err != nil {
 			if err != storage.ErrNotFound {
 				level.Debug(sl.l).Log("msg", "Unexpected error", "series", string(met), "err", err)
@@ -1645,7 +1676,7 @@ loop:
 				sl.cache.trackStaleness(hash, lset)
 			}
 			sl.cache.addRef(met, ref, lset, hash)
-			if sampleAdded && sampleLimitErr == nil {
+			if sampleAdded && sampleLimitErr == nil && bucketLimitErr == nil {
 				seriesAdded++
 			}
 		}
@@ -1681,6 +1712,13 @@ loop:
 		// We only want to increment this once per scrape, so this is Inc'd outside the loop.
 		targetScrapeSampleLimit.Inc()
 	}
+	if bucketLimitErr != nil {
+		if err == nil {
+			err = bucketLimitErr // If sample limit is hit, that error takes precedence.
+		}
+		// We only want to increment this once per scrape, so this is Inc'd outside the loop.
+		targetScrapeNativeHistogramBucketLimit.Inc()
+	}
 	if appErrs.numOutOfOrder > 0 {
 		level.Warn(sl.l).Log("msg", "Error on ingesting out-of-order samples", "num_dropped", appErrs.numOutOfOrder)
 	}
@@ -1710,8 +1748,8 @@ loop:
 }
 
 // Adds samples to the appender, checking the error, and then returns the # of samples added,
-// whether the caller should continue to process more samples, and any sample limit errors.
+// whether the caller should continue to process more samples, and any sample or bucket limit errors.
-func (sl *scrapeLoop) checkAddError(ce *cacheEntry, met []byte, tp *int64, err error, sampleLimitErr *error, appErrs *appendErrors) (bool, error) {
+func (sl *scrapeLoop) checkAddError(ce *cacheEntry, met []byte, tp *int64, err error, sampleLimitErr, bucketLimitErr *error, appErrs *appendErrors) (bool, error) {
 	switch errors.Cause(err) {
 	case nil:
 		if tp == nil && ce != nil {
@@ -1740,6 +1778,11 @@ func (sl *scrapeLoop) checkAddError(ce *cacheEntry, met []byte, tp *int64, err e
 		// total number of samples scraped.
 		*sampleLimitErr = err
 		return false, nil
+	case errBucketLimit:
+		// Keep on parsing output if we hit the limit, so we report the correct
+		// total number of samples scraped.
+		*bucketLimitErr = err
+		return false, nil
 	default:
 		return false, err
 	}

scrape/scrape_test.go

@@ -30,6 +30,7 @@ import (
 
 	"github.com/go-kit/log"
 	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
 	dto "github.com/prometheus/client_model/go"
 	config_util "github.com/prometheus/common/config"
 	"github.com/prometheus/common/model"
@@ -489,7 +490,7 @@ func TestScrapePoolAppender(t *testing.T) {
 	appl, ok := loop.(*scrapeLoop)
 	require.True(t, ok, "Expected scrapeLoop but got %T", loop)
 
-	wrapped := appender(appl.appender(context.Background()), 0)
+	wrapped := appender(appl.appender(context.Background()), 0, 0)
 
 	tl, ok := wrapped.(*timeLimitAppender)
 	require.True(t, ok, "Expected timeLimitAppender but got %T", wrapped)
@@ -505,7 +506,7 @@ func TestScrapePoolAppender(t *testing.T) {
 	appl, ok = loop.(*scrapeLoop)
 	require.True(t, ok, "Expected scrapeLoop but got %T", loop)
 
-	wrapped = appender(appl.appender(context.Background()), sampleLimit)
+	wrapped = appender(appl.appender(context.Background()), sampleLimit, 0)
 
 	sl, ok := wrapped.(*limitAppender)
 	require.True(t, ok, "Expected limitAppender but got %T", wrapped)
@@ -515,6 +516,20 @@ func TestScrapePoolAppender(t *testing.T) {
 
 	_, ok = tl.Appender.(nopAppender)
 	require.True(t, ok, "Expected base appender but got %T", tl.Appender)
+
+	wrapped = appender(appl.appender(context.Background()), sampleLimit, 100)
+
+	bl, ok := wrapped.(*bucketLimitAppender)
+	require.True(t, ok, "Expected bucketLimitAppender but got %T", wrapped)
+
+	sl, ok = bl.Appender.(*limitAppender)
+	require.True(t, ok, "Expected limitAppender but got %T", bl)
+
+	tl, ok = sl.Appender.(*timeLimitAppender)
+	require.True(t, ok, "Expected timeLimitAppender but got %T", sl.Appender)
+
+	_, ok = tl.Appender.(nopAppender)
+	require.True(t, ok, "Expected base appender but got %T", tl.Appender)
 }
 
 func TestScrapePoolRaces(t *testing.T) {
@@ -612,12 +627,13 @@ func TestScrapeLoopStopBeforeRun(t *testing.T) {
 		nopMutator,
 		nil, nil, 0,
 		true,
-		0,
+		0, 0,
 		nil,
 		1,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -684,12 +700,13 @@ func TestScrapeLoopStop(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		10*time.Millisecond,
 		time.Hour,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -760,12 +777,13 @@ func TestScrapeLoopRun(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		time.Second,
 		time.Hour,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -815,12 +833,13 @@ func TestScrapeLoopRun(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		time.Second,
 		100*time.Millisecond,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -874,12 +893,13 @@ func TestScrapeLoopForcedErr(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		time.Second,
 		time.Hour,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -932,12 +952,13 @@ func TestScrapeLoopMetadata(t *testing.T) {
 		cache,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -989,12 +1010,13 @@ func simpleTestScrapeLoop(t testing.TB) (context.Context, *scrapeLoop) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -1049,12 +1071,13 @@ func TestScrapeLoopFailWithInvalidLabelsAfterRelabel(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -1127,12 +1150,13 @@ func TestScrapeLoopRunCreatesStaleMarkersOnFailedScrape(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		10*time.Millisecond,
 		time.Hour,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -1190,12 +1214,13 @@ func TestScrapeLoopRunCreatesStaleMarkersOnParseFailure(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		10*time.Millisecond,
 		time.Hour,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -1256,12 +1281,13 @@ func TestScrapeLoopCache(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		10*time.Millisecond,
 		time.Hour,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -1339,12 +1365,13 @@ func TestScrapeLoopCacheMemoryExhaustionProtection(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		10*time.Millisecond,
 		time.Hour,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -1453,12 +1480,13 @@ func TestScrapeLoopAppend(t *testing.T) {
 			nil,
 			0,
 			true,
-			0,
+			0, 0,
 			nil,
 			0,
 			0,
 			false,
 			false,
+			false,
 			nil,
 			false,
 		)
@@ -1548,7 +1576,7 @@ func TestScrapeLoopAppendForConflictingPrefixedLabels(t *testing.T) {
 					return mutateSampleLabels(l, &Target{labels: labels.FromStrings(tc.targetLabels...)}, false, nil)
 				},
 				nil,
-				func(ctx context.Context) storage.Appender { return app }, nil, 0, true, 0, nil, 0, 0, false, false, nil, false,
+				func(ctx context.Context) storage.Appender { return app }, nil, 0, true, 0, 0, nil, 0, 0, false, false, false, nil, false,
 			)
 			slApp := sl.appender(context.Background())
 			_, _, _, err := sl.append(slApp, []byte(tc.exposedLabels), "", time.Date(2000, 1, 1, 1, 0, 0, 0, time.UTC))
@@ -1579,12 +1607,13 @@ func TestScrapeLoopAppendCacheEntryButErrNotFound(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -1592,7 +1621,7 @@ func TestScrapeLoopAppendCacheEntryButErrNotFound(t *testing.T) {
 	fakeRef := storage.SeriesRef(1)
 	expValue := float64(1)
 	metric := []byte(`metric{n="1"} 1`)
-	p, warning := textparse.New(metric, "")
+	p, warning := textparse.New(metric, "", false)
 	require.NoError(t, warning)
 
 	var lset labels.Labels
@@ -1637,12 +1666,13 @@ func TestScrapeLoopAppendSampleLimit(t *testing.T) {
 		nil,
 		0,
 		true,
-		app.limit,
+		app.limit, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -1697,6 +1727,105 @@ func TestScrapeLoopAppendSampleLimit(t *testing.T) {
 	require.Equal(t, 0, seriesAdded)
 }
 
+func TestScrapeLoop_HistogramBucketLimit(t *testing.T) {
+	resApp := &collectResultAppender{}
+	app := &bucketLimitAppender{Appender: resApp, limit: 2}
+
+	sl := newScrapeLoop(context.Background(),
+		nil, nil, nil,
+		func(l labels.Labels) labels.Labels {
+			if l.Has("deleteme") {
+				return labels.EmptyLabels()
+			}
+			return l
+		},
+		nopMutator,
+		func(ctx context.Context) storage.Appender { return app },
+		nil,
+		0,
+		true,
+		app.limit, 0,
+		nil,
+		0,
+		0,
+		false,
+		false,
+		false,
+		nil,
+		false,
+	)
+
+	metric := dto.Metric{}
+	err := targetScrapeNativeHistogramBucketLimit.Write(&metric)
+	require.NoError(t, err)
+	beforeMetricValue := metric.GetCounter().GetValue()
+
+	nativeHistogram := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Namespace:                      "testing",
+			Name:                           "example_native_histogram",
+			Help:                           "This is used for testing",
+			ConstLabels:                    map[string]string{"some": "value"},
+			NativeHistogramBucketFactor:    1.1, // 10% increase from bucket to bucket
+			NativeHistogramMaxBucketNumber: 100, // intentionally higher than the limit we'll use in the scraper
+		},
+		[]string{"size"},
+	)
+	registry := prometheus.NewRegistry()
+	registry.Register(nativeHistogram)
+	nativeHistogram.WithLabelValues("S").Observe(1.0)
+	nativeHistogram.WithLabelValues("M").Observe(1.0)
+	nativeHistogram.WithLabelValues("L").Observe(1.0)
+	nativeHistogram.WithLabelValues("M").Observe(10.0)
+	nativeHistogram.WithLabelValues("L").Observe(10.0) // in different bucket since > 1*1.1
+
+	gathered, err := registry.Gather()
+	require.NoError(t, err)
+	require.NotEmpty(t, gathered)
+
+	histogramMetricFamily := gathered[0]
+	msg, err := MetricFamilyToProtobuf(histogramMetricFamily)
+	require.NoError(t, err)
+
+	now := time.Now()
+	total, added, seriesAdded, err := sl.append(app, msg, "application/vnd.google.protobuf", now)
+	require.NoError(t, err)
+	require.Equal(t, 3, total)
+	require.Equal(t, 3, added)
+	require.Equal(t, 3, seriesAdded)
+
+	err = targetScrapeNativeHistogramBucketLimit.Write(&metric)
+	require.NoError(t, err)
+	metricValue := metric.GetCounter().GetValue()
+	require.Equal(t, beforeMetricValue, metricValue)
+	beforeMetricValue = metricValue
+
+	nativeHistogram.WithLabelValues("L").Observe(100.0) // in different bucket since > 10*1.1
+
+	gathered, err = registry.Gather()
+	require.NoError(t, err)
+	require.NotEmpty(t, gathered)
+
+	histogramMetricFamily = gathered[0]
+	msg, err = MetricFamilyToProtobuf(histogramMetricFamily)
+	require.NoError(t, err)
+
+	now = time.Now()
+	total, added, seriesAdded, err = sl.append(app, msg, "application/vnd.google.protobuf", now)
+	if err != errBucketLimit {
+		t.Fatalf("Did not see expected histogram bucket limit error: %s", err)
+	}
+	require.NoError(t, app.Rollback())
+	require.Equal(t, 3, total)
+	require.Equal(t, 3, added)
+	require.Equal(t, 0, seriesAdded)
+
+	err = targetScrapeNativeHistogramBucketLimit.Write(&metric)
+	require.NoError(t, err)
+	metricValue = metric.GetCounter().GetValue()
+	require.Equal(t, beforeMetricValue+1, metricValue)
+}
+
 func TestScrapeLoop_ChangingMetricString(t *testing.T) {
 	// This is a regression test for the scrape loop cache not properly maintaining
 	// IDs when the string representation of a metric changes across a scrape. Thus
@@ -1714,12 +1843,13 @@ func TestScrapeLoop_ChangingMetricString(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -1762,12 +1892,13 @@ func TestScrapeLoopAppendStaleness(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -1813,12 +1944,13 @@ func TestScrapeLoopAppendNoStalenessIfTimestamp(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -1924,12 +2056,13 @@ metric_total{n="2"} 2 # {t="2"} 2.0 20000
 				nil,
 				0,
 				true,
-				0,
+				0, 0,
 				nil,
 				0,
 				0,
 				false,
 				false,
+				false,
 				nil,
 				false,
 			)
@@ -1989,12 +2122,13 @@ func TestScrapeLoopAppendExemplarSeries(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -2041,12 +2175,13 @@ func TestScrapeLoopRunReportsTargetDownOnScrapeError(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		10*time.Millisecond,
 		time.Hour,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -2077,12 +2212,13 @@ func TestScrapeLoopRunReportsTargetDownOnInvalidUTF8(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		10*time.Millisecond,
 		time.Hour,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -2126,12 +2262,13 @@ func TestScrapeLoopAppendGracefullyIfAmendOrOutOfOrderOrOutOfBounds(t *testing.T
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -2171,12 +2308,13 @@ func TestScrapeLoopOutOfBoundsTimeError(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -2443,12 +2581,13 @@ func TestScrapeLoop_RespectTimestamps(t *testing.T) {
 		func(ctx context.Context) storage.Appender { return capp },
 		nil, 0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -2484,12 +2623,13 @@ func TestScrapeLoop_DiscardTimestamps(t *testing.T) {
 		func(ctx context.Context) storage.Appender { return capp },
 		nil, 0,
 		false,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -2524,12 +2664,13 @@ func TestScrapeLoopDiscardDuplicateLabels(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -2582,12 +2723,13 @@ func TestScrapeLoopDiscardUnnamedMetrics(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -2845,12 +2987,13 @@ func TestScrapeAddFast(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		0,
 		0,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -2908,7 +3051,7 @@ func TestReuseCacheRace(*testing.T) {
 func TestCheckAddError(t *testing.T) {
 	var appErrs appendErrors
 	sl := scrapeLoop{l: log.NewNopLogger()}
-	sl.checkAddError(nil, nil, nil, storage.ErrOutOfOrderSample, nil, &appErrs)
+	sl.checkAddError(nil, nil, nil, storage.ErrOutOfOrderSample, nil, nil, &appErrs)
 	require.Equal(t, 1, appErrs.numOutOfOrder)
 }
 
@@ -2931,12 +3074,13 @@ func TestScrapeReportSingleAppender(t *testing.T) {
 		nil,
 		0,
 		true,
-		0,
+		0, 0,
 		nil,
 		10*time.Millisecond,
 		time.Hour,
 		false,
 		false,
+		false,
 		nil,
 		false,
 	)
@@ -3133,12 +3277,13 @@ func TestScrapeLoopLabelLimit(t *testing.T) {
 			nil,
 			0,
 			true,
-			0,
+			0, 0,
 			&test.labelLimits,
 			0,
 			0,
 			false,
 			false,
+			false,
 			nil,
 			false,
 		)

scrape/target.go

@@ -27,6 +27,7 @@ import (
 
 	"github.com/prometheus/prometheus/config"
 	"github.com/prometheus/prometheus/discovery/targetgroup"
+	"github.com/prometheus/prometheus/model/histogram"
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/model/relabel"
 	"github.com/prometheus/prometheus/model/textparse"
@@ -313,7 +314,10 @@ func (ts Targets) Len() int           { return len(ts) }
 func (ts Targets) Less(i, j int) bool { return ts[i].URL().String() < ts[j].URL().String() }
 func (ts Targets) Swap(i, j int)      { ts[i], ts[j] = ts[j], ts[i] }
 
-var errSampleLimit = errors.New("sample limit exceeded")
+var (
+	errSampleLimit = errors.New("sample limit exceeded")
+	errBucketLimit = errors.New("histogram bucket limit exceeded")
+)
 
 // limitAppender limits the number of total appended samples in a batch.
 type limitAppender struct {
@@ -355,6 +359,31 @@ func (app *timeLimitAppender) Append(ref storage.SeriesRef, lset labels.Labels,
 	return ref, nil
 }
 
+// bucketLimitAppender limits the number of total appended samples in a batch.
+type bucketLimitAppender struct {
+	storage.Appender
+
+	limit int
+}
+
+func (app *bucketLimitAppender) AppendHistogram(ref storage.SeriesRef, lset labels.Labels, t int64, h *histogram.Histogram, fh *histogram.FloatHistogram) (storage.SeriesRef, error) {
+	if h != nil {
+		if len(h.PositiveBuckets)+len(h.NegativeBuckets) > app.limit {
+			return 0, errBucketLimit
+		}
+	}
+	if fh != nil {
+		if len(fh.PositiveBuckets)+len(fh.NegativeBuckets) > app.limit {
+			return 0, errBucketLimit
+		}
+	}
+	ref, err := app.Appender.AppendHistogram(ref, lset, t, h, fh)
+	if err != nil {
+		return 0, err
+	}
+	return ref, nil
+}
+
 // PopulateLabels builds a label set from the given label set and scrape configuration.
 // It returns a label set before relabeling was applied as the second return value.
 // Returns the original discovered label set found before relabelling was applied if the target is dropped during relabeling.

scrape/target_test.go

@@ -31,6 +31,7 @@ import (
 
 	"github.com/prometheus/prometheus/config"
 	"github.com/prometheus/prometheus/discovery/targetgroup"
+	"github.com/prometheus/prometheus/model/histogram"
 	"github.com/prometheus/prometheus/model/labels"
 )
 
@@ -488,3 +489,63 @@ scrape_configs:
 		})
 	}
 }
+
+func TestBucketLimitAppender(t *testing.T) {
+	example := histogram.Histogram{
+		Schema:        0,
+		Count:         21,
+		Sum:           33,
+		ZeroThreshold: 0.001,
+		ZeroCount:     3,
+		PositiveSpans: []histogram.Span{
+			{Offset: 0, Length: 3},
+		},
+		PositiveBuckets: []int64{3, 0, 0},
+		NegativeSpans: []histogram.Span{
+			{Offset: 0, Length: 3},
+		},
+		NegativeBuckets: []int64{3, 0, 0},
+	}
+
+	cases := []struct {
+		h           histogram.Histogram
+		limit       int
+		expectError bool
+	}{
+		{
+			h:           example,
+			limit:       3,
+			expectError: true,
+		},
+		{
+			h:           example,
+			limit:       10,
+			expectError: false,
+		},
+	}
+
+	resApp := &collectResultAppender{}
+
+	for _, c := range cases {
+		for _, floatHisto := range []bool{true, false} {
+			t.Run(fmt.Sprintf("floatHistogram=%t", floatHisto), func(t *testing.T) {
+				app := &bucketLimitAppender{Appender: resApp, limit: c.limit}
+				ts := int64(10 * time.Minute / time.Millisecond)
+				h := c.h
+				lbls := labels.FromStrings("__name__", "sparse_histogram_series")
+				var err error
+				if floatHisto {
+					_, err = app.AppendHistogram(0, lbls, ts, nil, h.Copy().ToFloat())
+				} else {
+					_, err = app.AppendHistogram(0, lbls, ts, h.Copy(), nil)
+				}
+				if c.expectError {
+					require.Error(t, err)
+				} else {
+					require.NoError(t, err)
+				}
+				require.NoError(t, app.Commit())
+			})
+		}
+	}
+}

storage/buffer.go

@@ -242,15 +242,16 @@ func (s fhSample) Type() chunkenc.ValueType {
 type sampleRing struct {
 	delta int64
 
-	// Lookback buffers. We use buf for mixed samples, but one of the three
+	// Lookback buffers. We use iBuf for mixed samples, but one of the three
 	// concrete ones for homogenous samples. (Only one of the four bufs is
 	// allowed to be populated!) This avoids the overhead of the interface
 	// wrapper for the happy (and by far most common) case of homogenous
 	// samples.
-	buf   []tsdbutil.Sample
+	iBuf     []tsdbutil.Sample
 	fBuf     []fSample
 	hBuf     []hSample
 	fhBuf    []fhSample
+	bufInUse bufType
 
 	i int // Position of most recent element in ring buffer.
 	f int // Position of first element in ring buffer.
@@ -259,6 +260,16 @@ type sampleRing struct {
 	it sampleRingIterator
 }
 
+type bufType int
+
+const (
+	noBuf bufType = iota // Nothing yet stored in sampleRing.
+	iBuf
+	fBuf
+	hBuf
+	fhBuf
+)
+
 // newSampleRing creates a new sampleRing. If you do not know the prefereed
 // value type yet, use a size of 0 (in which case the provided typ doesn't
 // matter). On the first add, a buffer of size 16 will be allocated with the
@@ -278,7 +289,7 @@ func newSampleRing(delta int64, size int, typ chunkenc.ValueType) *sampleRing {
 	case chunkenc.ValFloatHistogram:
 		r.fhBuf = make([]fhSample, size)
 	default:
-		r.buf = make([]tsdbutil.Sample, size)
+		r.iBuf = make([]tsdbutil.Sample, size)
 	}
 	return r
 }
@@ -287,6 +298,7 @@ func (r *sampleRing) reset() {
 	r.l = 0
 	r.i = -1
 	r.f = 0
+	r.bufInUse = noBuf
 }
 
 // Returns the current iterator. Invalidates previously returned iterators.
@@ -310,18 +322,18 @@ func (it *sampleRingIterator) Next() chunkenc.ValueType {
 	if it.i >= it.r.l {
 		return chunkenc.ValNone
 	}
-	switch {
+	switch it.r.bufInUse {
-	case len(it.r.fBuf) > 0:
+	case fBuf:
 		s := it.r.atF(it.i)
 		it.t = s.t
 		it.f = s.f
 		return chunkenc.ValFloat
-	case len(it.r.hBuf) > 0:
+	case hBuf:
 		s := it.r.atH(it.i)
 		it.t = s.t
 		it.h = s.h
 		return chunkenc.ValHistogram
-	case len(it.r.fhBuf) > 0:
+	case fhBuf:
 		s := it.r.atFH(it.i)
 		it.t = s.t
 		it.fh = s.fh
@@ -372,8 +384,8 @@ func (it *sampleRingIterator) AtT() int64 {
 }
 
 func (r *sampleRing) at(i int) tsdbutil.Sample {
-	j := (r.f + i) % len(r.buf)
+	j := (r.f + i) % len(r.iBuf)
-	return r.buf[j]
+	return r.iBuf[j]
 }
 
 func (r *sampleRing) atF(i int) fSample {
@@ -397,91 +409,113 @@ func (r *sampleRing) atFH(i int) fhSample {
 // from this package (fSample, hSample, fhSample), call one of the specialized
 // methods addF, addH, or addFH for better performance.
 func (r *sampleRing) add(s tsdbutil.Sample) {
-	if len(r.buf) == 0 {
+	if r.bufInUse == noBuf {
+		// First sample.
+		switch s := s.(type) {
+		case fSample:
+			r.bufInUse = fBuf
+			r.fBuf = addF(s, r.fBuf, r)
+		case hSample:
+			r.bufInUse = hBuf
+			r.hBuf = addH(s, r.hBuf, r)
+		case fhSample:
+			r.bufInUse = fhBuf
+			r.fhBuf = addFH(s, r.fhBuf, r)
+		}
+		return
+	}
+	if r.bufInUse != iBuf {
 		// Nothing added to the interface buf yet. Let's check if we can
 		// stay specialized.
 		switch s := s.(type) {
 		case fSample:
-			if len(r.hBuf)+len(r.fhBuf) == 0 {
+			if r.bufInUse == fBuf {
 				r.fBuf = addF(s, r.fBuf, r)
 				return
 			}
 		case hSample:
-			if len(r.fBuf)+len(r.fhBuf) == 0 {
+			if r.bufInUse == hBuf {
 				r.hBuf = addH(s, r.hBuf, r)
 				return
 			}
 		case fhSample:
-			if len(r.fBuf)+len(r.hBuf) == 0 {
+			if r.bufInUse == fhBuf {
 				r.fhBuf = addFH(s, r.fhBuf, r)
 				return
 			}
 		}
 		// The new sample isn't a fit for the already existing
 		// ones. Copy the latter into the interface buffer where needed.
-		switch {
+		switch r.bufInUse {
-		case len(r.fBuf) > 0:
+		case fBuf:
 			for _, s := range r.fBuf {
-				r.buf = append(r.buf, s)
+				r.iBuf = append(r.iBuf, s)
 			}
 			r.fBuf = nil
-		case len(r.hBuf) > 0:
+		case hBuf:
 			for _, s := range r.hBuf {
-				r.buf = append(r.buf, s)
+				r.iBuf = append(r.iBuf, s)
 			}
 			r.hBuf = nil
-		case len(r.fhBuf) > 0:
+		case fhBuf:
 			for _, s := range r.fhBuf {
-				r.buf = append(r.buf, s)
+				r.iBuf = append(r.iBuf, s)
 			}
 			r.fhBuf = nil
 		}
+		r.bufInUse = iBuf
 	}
-	r.buf = addSample(s, r.buf, r)
+	r.iBuf = addSample(s, r.iBuf, r)
 }
 
 // addF is a version of the add method specialized for fSample.
 func (r *sampleRing) addF(s fSample) {
-	switch {
+	switch r.bufInUse {
-	case len(r.buf) > 0:
+	case fBuf: // Add to existing fSamples.
-		// Already have interface samples. Add to the interface buf.
+		r.fBuf = addF(s, r.fBuf, r)
-		r.buf = addSample(s, r.buf, r)
+	case noBuf: // Add first sample.
-	case len(r.hBuf)+len(r.fhBuf) > 0:
+		r.fBuf = addF(s, r.fBuf, r)
+		r.bufInUse = fBuf
+	case iBuf: // Already have interface samples. Add to the interface buf.
+		r.iBuf = addSample(s, r.iBuf, r)
+	default:
 		// Already have specialized samples that are not fSamples.
 		// Need to call the checked add method for conversion.
 		r.add(s)
-	default:
-		r.fBuf = addF(s, r.fBuf, r)
 	}
 }
 
 // addH is a version of the add method specialized for hSample.
 func (r *sampleRing) addH(s hSample) {
-	switch {
+	switch r.bufInUse {
-	case len(r.buf) > 0:
+	case hBuf: // Add to existing hSamples.
-		// Already have interface samples. Add to the interface buf.
+		r.hBuf = addH(s, r.hBuf, r)
-		r.buf = addSample(s, r.buf, r)
+	case noBuf: // Add first sample.
-	case len(r.fBuf)+len(r.fhBuf) > 0:
+		r.hBuf = addH(s, r.hBuf, r)
-		// Already have samples that are not hSamples.
+		r.bufInUse = hBuf
+	case iBuf: // Already have interface samples. Add to the interface buf.
+		r.iBuf = addSample(s, r.iBuf, r)
+	default:
+		// Already have specialized samples that are not hSamples.
 		// Need to call the checked add method for conversion.
 		r.add(s)
-	default:
-		r.hBuf = addH(s, r.hBuf, r)
 	}
 }
 
 // addFH is a version of the add method specialized for fhSample.
 func (r *sampleRing) addFH(s fhSample) {
-	switch {
+	switch r.bufInUse {
-	case len(r.buf) > 0:
+	case fhBuf: // Add to existing fhSamples.
-		// Already have interface samples. Add to the interface buf.
+		r.fhBuf = addFH(s, r.fhBuf, r)
-		r.buf = addSample(s, r.buf, r)
+	case noBuf: // Add first sample.
-	case len(r.fBuf)+len(r.hBuf) > 0:
+		r.fhBuf = addFH(s, r.fhBuf, r)
-		// Already have samples that are not fhSamples.
+		r.bufInUse = fhBuf
+	case iBuf: // Already have interface samples. Add to the interface buf.
+		r.iBuf = addSample(s, r.iBuf, r)
+	default:
+		// Already have specialized samples that are not fhSamples.
 		// Need to call the checked add method for conversion.
 		r.add(s)
-	default:
-		r.fhBuf = addFH(s, r.fhBuf, r)
 	}
 }
 
@@ -701,15 +735,15 @@ func (r *sampleRing) reduceDelta(delta int64) bool {
 		return true
 	}
 
-	switch {
+	switch r.bufInUse {
-	case len(r.fBuf) > 0:
+	case fBuf:
 		genericReduceDelta(r.fBuf, r)
-	case len(r.hBuf) > 0:
+	case hBuf:
 		genericReduceDelta(r.hBuf, r)
-	case len(r.fhBuf) > 0:
+	case fhBuf:
 		genericReduceDelta(r.fhBuf, r)
 	default:
-		genericReduceDelta(r.buf, r)
+		genericReduceDelta(r.iBuf, r)
 	}
 	return true
 }
@@ -733,12 +767,12 @@ func (r *sampleRing) nthLast(n int) (tsdbutil.Sample, bool) {
 		return fSample{}, false
 	}
 	i := r.l - n
-	switch {
+	switch r.bufInUse {
-	case len(r.fBuf) > 0:
+	case fBuf:
 		return r.atF(i), true
-	case len(r.hBuf) > 0:
+	case hBuf:
 		return r.atH(i), true
-	case len(r.fhBuf) > 0:
+	case fhBuf:
 		return r.atFH(i), true
 	default:
 		return r.at(i), true
@@ -751,15 +785,15 @@ func (r *sampleRing) samples() []tsdbutil.Sample {
 	k := r.f + r.l
 	var j int
 
-	switch {
+	switch r.bufInUse {
-	case len(r.buf) > 0:
+	case iBuf:
-		if k > len(r.buf) {
+		if k > len(r.iBuf) {
-			k = len(r.buf)
+			k = len(r.iBuf)
 			j = r.l - k + r.f
 		}
-		n := copy(res, r.buf[r.f:k])
+		n := copy(res, r.iBuf[r.f:k])
-		copy(res[n:], r.buf[:j])
+		copy(res[n:], r.iBuf[:j])
-	case len(r.fBuf) > 0:
+	case fBuf:
 		if k > len(r.fBuf) {
 			k = len(r.fBuf)
 			j = r.l - k + r.f
@@ -770,7 +804,7 @@ func (r *sampleRing) samples() []tsdbutil.Sample {
 		for i, s := range resF {
 			res[i] = s
 		}
-	case len(r.hBuf) > 0:
+	case hBuf:
 		if k > len(r.hBuf) {
 			k = len(r.hBuf)
 			j = r.l - k + r.f
@@ -781,7 +815,7 @@ func (r *sampleRing) samples() []tsdbutil.Sample {
 		for i, s := range resH {
 			res[i] = s
 		}
-	case len(r.fhBuf) > 0:
+	case fhBuf:
 		if k > len(r.fhBuf) {
 			k = len(r.fhBuf)
 			j = r.l - k + r.f

storage/memoized_iterator.go

@@ -21,6 +21,9 @@ import (
 )
 
 // MemoizedSeriesIterator wraps an iterator with a buffer to look back the previous element.
+//
+// This iterator regards integer histograms as float histograms; calls to Seek() will never return chunkenc.Histogram.
+// This iterator deliberately does not implement chunkenc.Iterator.
 type MemoizedSeriesIterator struct {
 	it    chunkenc.Iterator
 	delta int64
@@ -31,12 +34,7 @@ type MemoizedSeriesIterator struct {
 	// Keep track of the previously returned value.
 	prevTime           int64
 	prevValue          float64
-	prevHistogram      *histogram.Histogram
 	prevFloatHistogram *histogram.FloatHistogram
-	// TODO(beorn7): MemoizedSeriesIterator is currently only used by the
-	// PromQL engine, which only works with FloatHistograms. For better
-	// performance, we could change MemoizedSeriesIterator to also only
-	// handle FloatHistograms.
 }
 
 // NewMemoizedEmptyIterator is like NewMemoizedIterator but it's initialised with an empty iterator.
@@ -66,11 +64,11 @@ func (b *MemoizedSeriesIterator) Reset(it chunkenc.Iterator) {
 
 // PeekPrev returns the previous element of the iterator. If there is none buffered,
 // ok is false.
-func (b *MemoizedSeriesIterator) PeekPrev() (t int64, v float64, h *histogram.Histogram, fh *histogram.FloatHistogram, ok bool) {
+func (b *MemoizedSeriesIterator) PeekPrev() (t int64, v float64, fh *histogram.FloatHistogram, ok bool) {
 	if b.prevTime == math.MinInt64 {
-		return 0, 0, nil, nil, false
+		return 0, 0, nil, false
 	}
-	return b.prevTime, b.prevValue, b.prevHistogram, b.prevFloatHistogram, true
+	return b.prevTime, b.prevValue, b.prevFloatHistogram, true
 }
 
 // Seek advances the iterator to the element at time t or greater.
@@ -83,8 +81,11 @@ func (b *MemoizedSeriesIterator) Seek(t int64) chunkenc.ValueType {
 		b.prevTime = math.MinInt64
 
 		b.valueType = b.it.Seek(t0)
-		if b.valueType == chunkenc.ValNone {
+		switch b.valueType {
+		case chunkenc.ValNone:
 			return chunkenc.ValNone
+		case chunkenc.ValHistogram:
+			b.valueType = chunkenc.ValFloatHistogram
 		}
 		b.lastTime = b.it.AtT()
 	}
@@ -100,7 +101,8 @@ func (b *MemoizedSeriesIterator) Seek(t int64) chunkenc.ValueType {
 	return chunkenc.ValNone
 }
 
-// Next advances the iterator to the next element.
+// Next advances the iterator to the next element. Note that this does not check whether the element being buffered is
+// within the time range of the current element and the duration of delta before.
 func (b *MemoizedSeriesIterator) Next() chunkenc.ValueType {
 	// Keep track of the previous element.
 	switch b.valueType {
@@ -108,15 +110,9 @@ func (b *MemoizedSeriesIterator) Next() chunkenc.ValueType {
 		return chunkenc.ValNone
 	case chunkenc.ValFloat:
 		b.prevTime, b.prevValue = b.it.At()
-		b.prevHistogram = nil
 		b.prevFloatHistogram = nil
-	case chunkenc.ValHistogram:
+	case chunkenc.ValHistogram, chunkenc.ValFloatHistogram:
 		b.prevValue = 0
-		b.prevTime, b.prevHistogram = b.it.AtHistogram()
-		_, b.prevFloatHistogram = b.it.AtFloatHistogram()
-	case chunkenc.ValFloatHistogram:
-		b.prevValue = 0
-		b.prevHistogram = nil
 		b.prevTime, b.prevFloatHistogram = b.it.AtFloatHistogram()
 	}
 
@@ -124,6 +120,9 @@ func (b *MemoizedSeriesIterator) Next() chunkenc.ValueType {
 	if b.valueType != chunkenc.ValNone {
 		b.lastTime = b.it.AtT()
 	}
+	if b.valueType == chunkenc.ValHistogram {
+		b.valueType = chunkenc.ValFloatHistogram
+	}
 	return b.valueType
 }
 
@@ -132,21 +131,11 @@ func (b *MemoizedSeriesIterator) At() (int64, float64) {
 	return b.it.At()
 }
 
-// AtHistogram returns the current histogram element of the iterator.
-func (b *MemoizedSeriesIterator) AtHistogram() (int64, *histogram.Histogram) {
-	return b.it.AtHistogram()
-}
-
 // AtFloatHistogram returns the current float-histogram element of the iterator.
 func (b *MemoizedSeriesIterator) AtFloatHistogram() (int64, *histogram.FloatHistogram) {
 	return b.it.AtFloatHistogram()
 }
 
-// AtT returns the current timestamp of the iterator.
-func (b *MemoizedSeriesIterator) AtT() int64 {
-	return b.it.AtT()
-}
-
 // Err returns the last encountered error.
 func (b *MemoizedSeriesIterator) Err() error {
 	return b.it.Err()

storage/memoized_iterator_test.go

@@ -18,23 +18,34 @@ import (
 
 	"github.com/stretchr/testify/require"
 
+	"github.com/prometheus/prometheus/model/histogram"
 	"github.com/prometheus/prometheus/tsdb/chunkenc"
+	"github.com/prometheus/prometheus/tsdb/tsdbutil"
 )
 
 func TestMemoizedSeriesIterator(t *testing.T) {
-	// TODO(beorn7): Include histograms in testing.
 	var it *MemoizedSeriesIterator
 
-	sampleEq := func(ets int64, ev float64) {
+	sampleEq := func(ets int64, ev float64, efh *histogram.FloatHistogram) {
+		if efh == nil {
 			ts, v := it.At()
 			require.Equal(t, ets, ts, "timestamp mismatch")
 			require.Equal(t, ev, v, "value mismatch")
+		} else {
+			ts, fh := it.AtFloatHistogram()
+			require.Equal(t, ets, ts, "timestamp mismatch")
+			require.Equal(t, efh, fh, "histogram mismatch")
 		}
-	prevSampleEq := func(ets int64, ev float64, eok bool) {
+	}
-		ts, v, _, _, ok := it.PeekPrev()
+	prevSampleEq := func(ets int64, ev float64, efh *histogram.FloatHistogram, eok bool) {
+		ts, v, fh, ok := it.PeekPrev()
 		require.Equal(t, eok, ok, "exist mismatch")
 		require.Equal(t, ets, ts, "timestamp mismatch")
+		if efh == nil {
 			require.Equal(t, ev, v, "value mismatch")
+		} else {
+			require.Equal(t, efh, fh, "histogram mismatch")
+		}
 	}
 
 	it = NewMemoizedIterator(NewListSeriesIterator(samples{
@@ -46,31 +57,50 @@ func TestMemoizedSeriesIterator(t *testing.T) {
 		fSample{t: 99, f: 8},
 		fSample{t: 100, f: 9},
 		fSample{t: 101, f: 10},
+		hSample{t: 102, h: tsdbutil.GenerateTestHistogram(0)},
+		hSample{t: 103, h: tsdbutil.GenerateTestHistogram(1)},
+		fhSample{t: 104, fh: tsdbutil.GenerateTestFloatHistogram(2)},
+		fhSample{t: 199, fh: tsdbutil.GenerateTestFloatHistogram(3)},
+		hSample{t: 200, h: tsdbutil.GenerateTestHistogram(4)},
+		fhSample{t: 299, fh: tsdbutil.GenerateTestFloatHistogram(5)},
+		fSample{t: 300, f: 11},
+		hSample{t: 399, h: tsdbutil.GenerateTestHistogram(6)},
+		fSample{t: 400, f: 12},
 	}), 2)
 
 	require.Equal(t, it.Seek(-123), chunkenc.ValFloat, "seek failed")
-	sampleEq(1, 2)
+	sampleEq(1, 2, nil)
-	prevSampleEq(0, 0, false)
+	prevSampleEq(0, 0, nil, false)
-
-	require.Equal(t, it.Next(), chunkenc.ValFloat, "next failed")
-	sampleEq(2, 3)
-	prevSampleEq(1, 2, true)
-
-	require.Equal(t, it.Next(), chunkenc.ValFloat, "next failed")
-	require.Equal(t, it.Next(), chunkenc.ValFloat, "next failed")
-	require.Equal(t, it.Next(), chunkenc.ValFloat, "next failed")
-	sampleEq(5, 6)
-	prevSampleEq(4, 5, true)
 
 	require.Equal(t, it.Seek(5), chunkenc.ValFloat, "seek failed")
-	sampleEq(5, 6)
+	sampleEq(5, 6, nil)
-	prevSampleEq(4, 5, true)
+	prevSampleEq(4, 5, nil, true)
 
-	require.Equal(t, it.Seek(101), chunkenc.ValFloat, "seek failed")
+	// Seek to a histogram sample with a previous float sample.
-	sampleEq(101, 10)
+	require.Equal(t, it.Seek(102), chunkenc.ValFloatHistogram, "seek failed")
-	prevSampleEq(100, 9, true)
+	sampleEq(102, 10, tsdbutil.GenerateTestFloatHistogram(0))
+	prevSampleEq(101, 10, nil, true)
+
+	// Attempt to seek backwards (no-op).
+	require.Equal(t, it.Seek(50), chunkenc.ValFloatHistogram, "seek failed")
+	sampleEq(102, 10, tsdbutil.GenerateTestFloatHistogram(0))
+	prevSampleEq(101, 10, nil, true)
+
+	// Seek to a float histogram sample with a previous histogram sample.
+	require.Equal(t, it.Seek(104), chunkenc.ValFloatHistogram, "seek failed")
+	sampleEq(104, 0, tsdbutil.GenerateTestFloatHistogram(2))
+	prevSampleEq(103, 0, tsdbutil.GenerateTestFloatHistogram(1), true)
+
+	// Seek to a float sample with a previous float histogram sample.
+	require.Equal(t, chunkenc.ValFloat, it.Seek(300), "seek failed")
+	sampleEq(300, 11, nil)
+	prevSampleEq(299, 0, tsdbutil.GenerateTestFloatHistogram(5), true)
+
+	// Seek to a float sample with a previous histogram sample.
+	require.Equal(t, chunkenc.ValFloat, it.Seek(400), "seek failed")
+	sampleEq(400, 12, nil)
+	prevSampleEq(399, 0, tsdbutil.GenerateTestFloatHistogram(6), true)
 
-	require.Equal(t, it.Next(), chunkenc.ValNone, "next succeeded unexpectedly")
 	require.Equal(t, it.Seek(1024), chunkenc.ValNone, "seek succeeded unexpectedly")
 }
 

storage/remote/storage.go

@@ -76,6 +76,13 @@ func NewStorage(l log.Logger, reg prometheus.Registerer, stCallback startTimeCal
 	return s
 }
 
+func (s *Storage) Notify() {
+	for _, q := range s.rws.queues {
+		// These should all be non blocking
+		q.watcher.Notify()
+	}
+}
+
 // ApplyConfig updates the state as the new config requires.
 func (s *Storage) ApplyConfig(conf *config.Config) error {
 	s.mtx.Lock()

storage/series.go

@@ -297,9 +297,11 @@ func (s *seriesToChunkEncoder) Iterator(it chunks.Iterator) chunks.Iterator {
 	seriesIter := s.Series.Iterator(nil)
 	lastType := chunkenc.ValNone
 	for typ := seriesIter.Next(); typ != chunkenc.ValNone; typ = seriesIter.Next() {
+		chunkCreated := false
 		if typ != lastType || i >= seriesToChunkEncoderSplit {
 			// Create a new chunk if the sample type changed or too many samples in the current one.
 			chks = appendChunk(chks, mint, maxt, chk)
+			chunkCreated = true
 			chk, err = chunkenc.NewEmptyChunk(typ.ChunkEncoding())
 			if err != nil {
 				return errChunksIterator{err: err}
@@ -330,6 +332,7 @@ func (s *seriesToChunkEncoder) Iterator(it chunks.Iterator) chunks.Iterator {
 			if ok, counterReset := app.AppendHistogram(t, h); !ok {
 				chks = appendChunk(chks, mint, maxt, chk)
 				histChunk := chunkenc.NewHistogramChunk()
+				chunkCreated = true
 				if counterReset {
 					histChunk.SetCounterResetHeader(chunkenc.CounterReset)
 				}
@@ -346,11 +349,15 @@ func (s *seriesToChunkEncoder) Iterator(it chunks.Iterator) chunks.Iterator {
 					panic("unexpected error while appending histogram")
 				}
 			}
+			if chunkCreated && h.CounterResetHint == histogram.GaugeType {
+				chk.(*chunkenc.HistogramChunk).SetCounterResetHeader(chunkenc.GaugeType)
+			}
 		case chunkenc.ValFloatHistogram:
 			t, fh = seriesIter.AtFloatHistogram()
 			if ok, counterReset := app.AppendFloatHistogram(t, fh); !ok {
 				chks = appendChunk(chks, mint, maxt, chk)
 				floatHistChunk := chunkenc.NewFloatHistogramChunk()
+				chunkCreated = true
 				if counterReset {
 					floatHistChunk.SetCounterResetHeader(chunkenc.CounterReset)
 				}
@@ -366,6 +373,9 @@ func (s *seriesToChunkEncoder) Iterator(it chunks.Iterator) chunks.Iterator {
 					panic("unexpected error while float appending histogram")
 				}
 			}
+			if chunkCreated && fh.CounterResetHint == histogram.GaugeType {
+				chk.(*chunkenc.FloatHistogramChunk).SetCounterResetHeader(chunkenc.GaugeType)
+			}
 		default:
 			return errChunksIterator{err: fmt.Errorf("unknown sample type %s", typ.String())}
 		}

storage/series_test.go

@@ -127,13 +127,12 @@ func TestChunkSeriesSetToSeriesSet(t *testing.T) {
 
 type histogramTest struct {
 	samples                     []tsdbutil.Sample
-	expectedChunks       int
+	expectedCounterResetHeaders []chunkenc.CounterResetHeader
-	expectedCounterReset bool
 }
 
 func TestHistogramSeriesToChunks(t *testing.T) {
 	h1 := &histogram.Histogram{
-		Count:         3,
+		Count:         7,
 		ZeroCount:     2,
 		ZeroThreshold: 0.001,
 		Sum:           100,
@@ -158,7 +157,7 @@ func TestHistogramSeriesToChunks(t *testing.T) {
 	}
 	// Implicit counter reset by reduction in buckets, not appendable.
 	h2down := &histogram.Histogram{
-		Count:         8,
+		Count:         10,
 		ZeroCount:     2,
 		ZeroThreshold: 0.001,
 		Sum:           100,
@@ -171,7 +170,7 @@ func TestHistogramSeriesToChunks(t *testing.T) {
 	}
 
 	fh1 := &histogram.FloatHistogram{
-		Count:         4,
+		Count:         6,
 		ZeroCount:     2,
 		ZeroThreshold: 0.001,
 		Sum:           100,
@@ -183,7 +182,7 @@ func TestHistogramSeriesToChunks(t *testing.T) {
 	}
 	// Appendable to fh1.
 	fh2 := &histogram.FloatHistogram{
-		Count:         15,
+		Count:         17,
 		ZeroCount:     2,
 		ZeroThreshold: 0.001,
 		Sum:           100,
@@ -196,7 +195,7 @@ func TestHistogramSeriesToChunks(t *testing.T) {
 	}
 	// Implicit counter reset by reduction in buckets, not appendable.
 	fh2down := &histogram.FloatHistogram{
-		Count:         13,
+		Count:         15,
 		ZeroCount:     2,
 		ZeroThreshold: 0.001,
 		Sum:           100,
@@ -208,6 +207,60 @@ func TestHistogramSeriesToChunks(t *testing.T) {
 		PositiveBuckets: []float64{2, 2, 7, 2},
 	}
 
+	// Gauge histogram.
+	gh1 := &histogram.Histogram{
+		CounterResetHint: histogram.GaugeType,
+		Count:            7,
+		ZeroCount:        2,
+		ZeroThreshold:    0.001,
+		Sum:              100,
+		Schema:           0,
+		PositiveSpans: []histogram.Span{
+			{Offset: 0, Length: 2},
+		},
+		PositiveBuckets: []int64{2, 1}, // Abs: 2, 3
+	}
+	gh2 := &histogram.Histogram{
+		CounterResetHint: histogram.GaugeType,
+		Count:            12,
+		ZeroCount:        2,
+		ZeroThreshold:    0.001,
+		Sum:              100,
+		Schema:           0,
+		PositiveSpans: []histogram.Span{
+			{Offset: 0, Length: 2},
+			{Offset: 1, Length: 2},
+		},
+		PositiveBuckets: []int64{2, 1, -2, 3}, // Abs: 2, 3, 1, 4
+	}
+
+	// Float gauge histogram.
+	gfh1 := &histogram.FloatHistogram{
+		CounterResetHint: histogram.GaugeType,
+		Count:            6,
+		ZeroCount:        2,
+		ZeroThreshold:    0.001,
+		Sum:              100,
+		Schema:           0,
+		PositiveSpans: []histogram.Span{
+			{Offset: 0, Length: 2},
+		},
+		PositiveBuckets: []float64{3, 1},
+	}
+	gfh2 := &histogram.FloatHistogram{
+		CounterResetHint: histogram.GaugeType,
+		Count:            17,
+		ZeroCount:        2,
+		ZeroThreshold:    0.001,
+		Sum:              100,
+		Schema:           0,
+		PositiveSpans: []histogram.Span{
+			{Offset: 0, Length: 2},
+			{Offset: 1, Length: 2},
+		},
+		PositiveBuckets: []float64{4, 2, 7, 2},
+	}
+
 	staleHistogram := &histogram.Histogram{
 		Sum: math.Float64frombits(value.StaleNaN),
 	}
@@ -220,74 +273,70 @@ func TestHistogramSeriesToChunks(t *testing.T) {
 			samples: []tsdbutil.Sample{
 				hSample{t: 1, h: h1},
 			},
-			expectedChunks: 1,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset},
 		},
 		"two histograms encoded to a single chunk": {
 			samples: []tsdbutil.Sample{
 				hSample{t: 1, h: h1},
 				hSample{t: 2, h: h2},
 			},
-			expectedChunks: 1,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset},
 		},
 		"two histograms encoded to two chunks": {
 			samples: []tsdbutil.Sample{
 				hSample{t: 1, h: h2},
 				hSample{t: 2, h: h1},
 			},
-			expectedChunks:       2,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset, chunkenc.CounterReset},
-			expectedCounterReset: true,
 		},
 		"histogram and stale sample encoded to two chunks": {
 			samples: []tsdbutil.Sample{
 				hSample{t: 1, h: staleHistogram},
 				hSample{t: 2, h: h1},
 			},
-			expectedChunks: 2,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset, chunkenc.UnknownCounterReset},
 		},
 		"histogram and reduction in bucket encoded to two chunks": {
 			samples: []tsdbutil.Sample{
 				hSample{t: 1, h: h1},
 				hSample{t: 2, h: h2down},
 			},
-			expectedChunks:       2,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset, chunkenc.CounterReset},
-			expectedCounterReset: true,
 		},
 		// Float histograms.
 		"single float histogram to single chunk": {
 			samples: []tsdbutil.Sample{
 				fhSample{t: 1, fh: fh1},
 			},
-			expectedChunks: 1,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset},
 		},
 		"two float histograms encoded to a single chunk": {
 			samples: []tsdbutil.Sample{
 				fhSample{t: 1, fh: fh1},
 				fhSample{t: 2, fh: fh2},
 			},
-			expectedChunks: 1,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset},
 		},
 		"two float histograms encoded to two chunks": {
 			samples: []tsdbutil.Sample{
 				fhSample{t: 1, fh: fh2},
 				fhSample{t: 2, fh: fh1},
 			},
-			expectedChunks:       2,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset, chunkenc.CounterReset},
-			expectedCounterReset: true,
 		},
 		"float histogram and stale sample encoded to two chunks": {
 			samples: []tsdbutil.Sample{
 				fhSample{t: 1, fh: staleFloatHistogram},
 				fhSample{t: 2, fh: fh1},
 			},
-			expectedChunks: 2,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset, chunkenc.UnknownCounterReset},
 		},
 		"float histogram and reduction in bucket encoded to two chunks": {
 			samples: []tsdbutil.Sample{
 				fhSample{t: 1, fh: fh1},
 				fhSample{t: 2, fh: fh2down},
 			},
-			expectedChunks:       2,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset, chunkenc.CounterReset},
-			expectedCounterReset: true,
 		},
 		// Mixed.
 		"histogram and float histogram encoded to two chunks": {
@@ -295,21 +344,61 @@ func TestHistogramSeriesToChunks(t *testing.T) {
 				hSample{t: 1, h: h1},
 				fhSample{t: 2, fh: fh2},
 			},
-			expectedChunks: 2,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset, chunkenc.UnknownCounterReset},
 		},
 		"float histogram and histogram encoded to two chunks": {
 			samples: []tsdbutil.Sample{
 				fhSample{t: 1, fh: fh1},
 				hSample{t: 2, h: h2},
 			},
-			expectedChunks: 2,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset, chunkenc.UnknownCounterReset},
 		},
 		"histogram and stale float histogram encoded to two chunks": {
 			samples: []tsdbutil.Sample{
 				hSample{t: 1, h: h1},
 				fhSample{t: 2, fh: staleFloatHistogram},
 			},
-			expectedChunks: 2,
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.UnknownCounterReset, chunkenc.UnknownCounterReset},
+		},
+		"single gauge histogram encoded to one chunk": {
+			samples: []tsdbutil.Sample{
+				hSample{t: 1, h: gh1},
+			},
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.GaugeType},
+		},
+		"two gauge histograms encoded to one chunk when counter increases": {
+			samples: []tsdbutil.Sample{
+				hSample{t: 1, h: gh1},
+				hSample{t: 2, h: gh2},
+			},
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.GaugeType},
+		},
+		"two gauge histograms encoded to one chunk when counter decreases": {
+			samples: []tsdbutil.Sample{
+				hSample{t: 1, h: gh2},
+				hSample{t: 2, h: gh1},
+			},
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.GaugeType},
+		},
+		"single gauge float histogram encoded to one chunk": {
+			samples: []tsdbutil.Sample{
+				fhSample{t: 1, fh: gfh1},
+			},
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.GaugeType},
+		},
+		"two float gauge histograms encoded to one chunk when counter increases": {
+			samples: []tsdbutil.Sample{
+				fhSample{t: 1, fh: gfh1},
+				fhSample{t: 2, fh: gfh2},
+			},
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.GaugeType},
+		},
+		"two float gauge histograms encoded to one chunk when counter decreases": {
+			samples: []tsdbutil.Sample{
+				fhSample{t: 1, fh: gfh2},
+				fhSample{t: 2, fh: gfh1},
+			},
+			expectedCounterResetHeaders: []chunkenc.CounterResetHeader{chunkenc.GaugeType},
 		},
 	}
 
@@ -322,13 +411,24 @@ func TestHistogramSeriesToChunks(t *testing.T) {
 
 func testHistogramsSeriesToChunks(t *testing.T, test histogramTest) {
 	lbs := labels.FromStrings("__name__", "up", "instance", "localhost:8080")
-	series := NewListSeries(lbs, test.samples)
+	copiedSamples := []tsdbutil.Sample{}
+	for _, s := range test.samples {
+		switch cs := s.(type) {
+		case hSample:
+			copiedSamples = append(copiedSamples, hSample{t: cs.t, h: cs.h.Copy()})
+		case fhSample:
+			copiedSamples = append(copiedSamples, fhSample{t: cs.t, fh: cs.fh.Copy()})
+		default:
+			t.Error("internal error, unexpected type")
+		}
+	}
+	series := NewListSeries(lbs, copiedSamples)
 	encoder := NewSeriesToChunkEncoder(series)
 	require.EqualValues(t, lbs, encoder.Labels())
 
 	chks, err := ExpandChunks(encoder.Iterator(nil))
 	require.NoError(t, err)
-	require.Equal(t, test.expectedChunks, len(chks))
+	require.Equal(t, len(test.expectedCounterResetHeaders), len(chks))
 
 	// Decode all encoded samples and assert they are equal to the original ones.
 	encodedSamples := expandHistogramSamples(chks)
@@ -339,8 +439,10 @@ func testHistogramsSeriesToChunks(t *testing.T, test histogramTest) {
 		case hSample:
 			encodedSample, ok := encodedSamples[i].(hSample)
 			require.True(t, ok, "expect histogram", fmt.Sprintf("at idx %d", i))
-			// Ignore counter reset here, will check on chunk level.
+			// Ignore counter reset if not gauge here, will check on chunk level.
+			if expectedSample.h.CounterResetHint != histogram.GaugeType {
 				encodedSample.h.CounterResetHint = histogram.UnknownCounterReset
+			}
 			if value.IsStaleNaN(expectedSample.h.Sum) {
 				require.True(t, value.IsStaleNaN(encodedSample.h.Sum), fmt.Sprintf("at idx %d", i))
 				continue
@@ -349,8 +451,10 @@ func testHistogramsSeriesToChunks(t *testing.T, test histogramTest) {
 		case fhSample:
 			encodedSample, ok := encodedSamples[i].(fhSample)
 			require.True(t, ok, "expect float histogram", fmt.Sprintf("at idx %d", i))
-			// Ignore counter reset here, will check on chunk level.
+			// Ignore counter reset if not gauge here, will check on chunk level.
+			if expectedSample.fh.CounterResetHint != histogram.GaugeType {
 				encodedSample.fh.CounterResetHint = histogram.UnknownCounterReset
+			}
 			if value.IsStaleNaN(expectedSample.fh.Sum) {
 				require.True(t, value.IsStaleNaN(encodedSample.fh.Sum), fmt.Sprintf("at idx %d", i))
 				continue
@@ -361,15 +465,8 @@ func testHistogramsSeriesToChunks(t *testing.T, test histogramTest) {
 		}
 	}
 
-	// If a counter reset hint is expected, it can only be found in the second chunk.
+	for i, expectedCounterResetHint := range test.expectedCounterResetHeaders {
-	// Otherwise, we assert an unknown counter reset hint in all chunks.
+		require.Equal(t, expectedCounterResetHint, getCounterResetHint(chks[i]), fmt.Sprintf("chunk at index %d", i))
-	if test.expectedCounterReset {
-		require.Equal(t, chunkenc.UnknownCounterReset, getCounterResetHint(chks[0]))
-		require.Equal(t, chunkenc.CounterReset, getCounterResetHint(chks[1]))
-	} else {
-		for _, chk := range chks {
-			require.Equal(t, chunkenc.UnknownCounterReset, getCounterResetHint(chk))
-		}
 	}
 }
 

tsdb/agent/db.go

@@ -665,7 +665,7 @@ func (db *DB) truncate(mint int64) error {
 		}
 
 		seg, ok := db.deleted[id]
-		return ok && seg >= first
+		return ok && seg > last
 	}
 
 	db.metrics.checkpointCreationTotal.Inc()
@@ -687,7 +687,7 @@ func (db *DB) truncate(mint int64) error {
 	// The checkpoint is written and segments before it are truncated, so we
 	// no longer need to track deleted series that were being kept around.
 	for ref, segment := range db.deleted {
-		if segment < first {
+		if segment <= last {
 			delete(db.deleted, ref)
 		}
 	}

tsdb/chunkenc/float_histogram.go

@@ -358,9 +358,9 @@ func counterResetInAnyFloatBucket(oldBuckets []xorValue, newBuckets []float64, o
 
 		if oldIdx <= newIdx {
 			// Moving ahead old bucket and span by 1 index.
-			if oldInsideSpanIdx == oldSpans[oldSpanSliceIdx].Length-1 {
+			if oldInsideSpanIdx+1 >= oldSpans[oldSpanSliceIdx].Length {
 				// Current span is over.
-				oldSpanSliceIdx++
+				oldSpanSliceIdx = nextNonEmptySpanSliceIdx(oldSpanSliceIdx, oldSpans)
 				oldInsideSpanIdx = 0
 				if oldSpanSliceIdx >= len(oldSpans) {
 					// All old spans are over.
@@ -377,9 +377,9 @@ func counterResetInAnyFloatBucket(oldBuckets []xorValue, newBuckets []float64, o
 
 		if oldIdx > newIdx {
 			// Moving ahead new bucket and span by 1 index.
-			if newInsideSpanIdx == newSpans[newSpanSliceIdx].Length-1 {
+			if newInsideSpanIdx+1 >= newSpans[newSpanSliceIdx].Length {
 				// Current span is over.
-				newSpanSliceIdx++
+				newSpanSliceIdx = nextNonEmptySpanSliceIdx(newSpanSliceIdx, newSpans)
 				newInsideSpanIdx = 0
 				if newSpanSliceIdx >= len(newSpans) {
 					// All new spans are over.

tsdb/chunkenc/float_histogram_test.go

@@ -365,6 +365,64 @@ func TestFloatHistogramChunkAppendable(t *testing.T) {
 	}
 }
 
+func TestFloatHistogramChunkAppendableWithEmptySpan(t *testing.T) {
+	h1 := &histogram.FloatHistogram{
+		Schema:        0,
+		Count:         21,
+		Sum:           1234.5,
+		ZeroThreshold: 0.001,
+		ZeroCount:     4,
+		PositiveSpans: []histogram.Span{
+			{Offset: 0, Length: 4},
+			{Offset: 0, Length: 0},
+			{Offset: 0, Length: 3},
+		},
+		PositiveBuckets: []float64{1, 2, 1, 1, 1, 1, 1},
+		NegativeSpans: []histogram.Span{
+			{Offset: 1, Length: 4},
+			{Offset: 2, Length: 0},
+			{Offset: 2, Length: 3},
+		},
+		NegativeBuckets: []float64{1, 2, 1, 2, 2, 2, 2},
+	}
+	h2 := &histogram.FloatHistogram{
+		Schema:        0,
+		Count:         37,
+		Sum:           2345.6,
+		ZeroThreshold: 0.001,
+		ZeroCount:     5,
+		PositiveSpans: []histogram.Span{
+			{Offset: 0, Length: 4},
+			{Offset: 0, Length: 0},
+			{Offset: 0, Length: 3},
+		},
+		PositiveBuckets: []float64{1, 3, 1, 2, 1, 1, 1},
+		NegativeSpans: []histogram.Span{
+			{Offset: 1, Length: 4},
+			{Offset: 2, Length: 0},
+			{Offset: 2, Length: 3},
+		},
+		NegativeBuckets: []float64{1, 4, 2, 7, 5, 5, 2},
+	}
+
+	c := Chunk(NewFloatHistogramChunk())
+
+	// Create fresh appender and add the first histogram.
+	app, err := c.Appender()
+	require.NoError(t, err)
+	require.Equal(t, 0, c.NumSamples())
+
+	app.AppendFloatHistogram(1, h1)
+	require.Equal(t, 1, c.NumSamples())
+	hApp, _ := app.(*FloatHistogramAppender)
+
+	pI, nI, okToAppend, counterReset := hApp.Appendable(h2)
+	require.Empty(t, pI)
+	require.Empty(t, nI)
+	require.True(t, okToAppend)
+	require.False(t, counterReset)
+}
+
 func TestFloatHistogramChunkAppendableGauge(t *testing.T) {
 	c := Chunk(NewFloatHistogramChunk())
 

tsdb/chunkenc/histogram.go

@@ -386,9 +386,9 @@ func counterResetInAnyBucket(oldBuckets, newBuckets []int64, oldSpans, newSpans
 
 		if oldIdx <= newIdx {
 			// Moving ahead old bucket and span by 1 index.
-			if oldInsideSpanIdx == oldSpans[oldSpanSliceIdx].Length-1 {
+			if oldInsideSpanIdx+1 >= oldSpans[oldSpanSliceIdx].Length {
 				// Current span is over.
-				oldSpanSliceIdx++
+				oldSpanSliceIdx = nextNonEmptySpanSliceIdx(oldSpanSliceIdx, oldSpans)
 				oldInsideSpanIdx = 0
 				if oldSpanSliceIdx >= len(oldSpans) {
 					// All old spans are over.
@@ -405,9 +405,9 @@ func counterResetInAnyBucket(oldBuckets, newBuckets []int64, oldSpans, newSpans
 
 		if oldIdx > newIdx {
 			// Moving ahead new bucket and span by 1 index.
-			if newInsideSpanIdx == newSpans[newSpanSliceIdx].Length-1 {
+			if newInsideSpanIdx+1 >= newSpans[newSpanSliceIdx].Length {
 				// Current span is over.
-				newSpanSliceIdx++
+				newSpanSliceIdx = nextNonEmptySpanSliceIdx(newSpanSliceIdx, newSpans)
 				newInsideSpanIdx = 0
 				if newSpanSliceIdx >= len(newSpans) {
 					// All new spans are over.

tsdb/chunkenc/histogram_meta.go

@@ -487,3 +487,10 @@ func counterResetHint(crh CounterResetHeader, numRead uint16) histogram.CounterR
 		return histogram.UnknownCounterReset
 	}
 }
+
+// Handle pathological case of empty span when advancing span idx.
+func nextNonEmptySpanSliceIdx(idx int, spans []histogram.Span) (newIdx int) {
+	for idx++; idx < len(spans) && spans[idx].Length == 0; idx++ { //nolint:revive // This "empty" block is intentional
+	}
+	return idx
+}

tsdb/chunkenc/histogram_test.go

@@ -14,6 +14,7 @@
 package chunkenc
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -387,6 +388,64 @@ func TestHistogramChunkAppendable(t *testing.T) {
 	}
 }
 
+func TestHistogramChunkAppendableWithEmptySpan(t *testing.T) {
+	h1 := &histogram.Histogram{
+		Schema:        0,
+		Count:         21,
+		Sum:           1234.5,
+		ZeroThreshold: 0.001,
+		ZeroCount:     4,
+		PositiveSpans: []histogram.Span{
+			{Offset: 0, Length: 4},
+			{Offset: 0, Length: 0},
+			{Offset: 0, Length: 3},
+		},
+		PositiveBuckets: []int64{1, 1, -1, 0, 0, 0, 0},
+		NegativeSpans: []histogram.Span{
+			{Offset: 1, Length: 4},
+			{Offset: 2, Length: 0},
+			{Offset: 2, Length: 3},
+		},
+		NegativeBuckets: []int64{1, 1, -1, 1, 0, 0, 0},
+	}
+	h2 := &histogram.Histogram{
+		Schema:        0,
+		Count:         37,
+		Sum:           2345.6,
+		ZeroThreshold: 0.001,
+		ZeroCount:     5,
+		PositiveSpans: []histogram.Span{
+			{Offset: 0, Length: 4},
+			{Offset: 0, Length: 0},
+			{Offset: 0, Length: 3},
+		},
+		PositiveBuckets: []int64{1, 2, -2, 1, -1, 0, 0},
+		NegativeSpans: []histogram.Span{
+			{Offset: 1, Length: 4},
+			{Offset: 2, Length: 0},
+			{Offset: 2, Length: 3},
+		},
+		NegativeBuckets: []int64{1, 3, -2, 5, -2, 0, -3},
+	}
+
+	c := Chunk(NewHistogramChunk())
+
+	// Create fresh appender and add the first histogram.
+	app, err := c.Appender()
+	require.NoError(t, err)
+	require.Equal(t, 0, c.NumSamples())
+
+	app.AppendHistogram(1, h1)
+	require.Equal(t, 1, c.NumSamples())
+	hApp, _ := app.(*HistogramAppender)
+
+	pI, nI, okToAppend, counterReset := hApp.Appendable(h2)
+	require.Empty(t, pI)
+	require.Empty(t, nI)
+	require.True(t, okToAppend)
+	require.False(t, counterReset)
+}
+
 func TestAtFloatHistogram(t *testing.T) {
 	input := []histogram.Histogram{
 		{
@@ -514,6 +573,10 @@ func TestAtFloatHistogram(t *testing.T) {
 	app, err := chk.Appender()
 	require.NoError(t, err)
 	for i := range input {
+		if i > 0 {
+			_, _, okToAppend, _ := app.(*HistogramAppender).Appendable(&input[i])
+			require.True(t, okToAppend, fmt.Sprintf("idx: %d", i))
+		}
 		app.AppendHistogram(int64(i), &input[i])
 	}
 	it := chk.Iterator(nil)

tsdb/compact.go

@@ -896,10 +896,10 @@ func debugOutOfOrderChunks(chks []chunks.Meta, logger log.Logger) {
 		}
 
 		// Looks like the chunk is out of order.
-		prevSafeChk, prevIsSafeChk := prevChk.Chunk.(*safeChunk)
+		prevSafeChk, prevIsSafeChk := prevChk.Chunk.(*safeHeadChunk)
-		currSafeChk, currIsSafeChk := currChk.Chunk.(*safeChunk)
+		currSafeChk, currIsSafeChk := currChk.Chunk.(*safeHeadChunk)
 
-		// Get info out of safeChunk (if possible).
+		// Get info out of safeHeadChunk (if possible).
 		prevHeadChunkID := chunks.HeadChunkID(0)
 		currHeadChunkID := chunks.HeadChunkID(0)
 		prevLabels := labels.Labels{}

tsdb/db.go

@@ -80,6 +80,7 @@ func DefaultOptions() *Options {
 		NoLockfile:                         false,
 		AllowOverlappingCompaction:         true,
 		WALCompression:                     false,
+		SamplesPerChunk:                    DefaultSamplesPerChunk,
 		StripeSize:                         DefaultStripeSize,
 		HeadChunksWriteBufferSize:          chunks.DefaultWriteBufferSize,
 		IsolationDisabled:                  defaultIsolationDisabled,
@@ -162,6 +163,9 @@ type Options struct {
 	// HeadChunksWriteQueueSize configures the size of the chunk write queue used in the head chunks mapper.
 	HeadChunksWriteQueueSize int
 
+	// SamplesPerChunk configures the target number of samples per chunk.
+	SamplesPerChunk int
+
 	// SeriesLifecycleCallback specifies a list of callbacks that will be called during a lifecycle of a series.
 	// It is always a no-op in Prometheus and mainly meant for external users who import TSDB.
 	SeriesLifecycleCallback SeriesLifecycleCallback
@@ -265,6 +269,8 @@ type DB struct {
 	// out-of-order compaction and vertical queries.
 	oooWasEnabled atomic.Bool
 
+	writeNotified wlog.WriteNotified
+
 	registerer prometheus.Registerer
 }
 
@@ -678,6 +684,9 @@ func validateOpts(opts *Options, rngs []int64) (*Options, []int64) {
 	if opts.HeadChunksWriteQueueSize < 0 {
 		opts.HeadChunksWriteQueueSize = chunks.DefaultWriteQueueSize
 	}
+	if opts.SamplesPerChunk <= 0 {
+		opts.SamplesPerChunk = DefaultSamplesPerChunk
+	}
 	if opts.MaxBlockChunkSegmentSize <= 0 {
 		opts.MaxBlockChunkSegmentSize = chunks.DefaultChunkSegmentSize
 	}
@@ -823,6 +832,7 @@ func open(dir string, l log.Logger, r prometheus.Registerer, opts *Options, rngs
 	headOpts.ChunkWriteBufferSize = opts.HeadChunksWriteBufferSize
 	headOpts.ChunkEndTimeVariance = opts.HeadChunksEndTimeVariance
 	headOpts.ChunkWriteQueueSize = opts.HeadChunksWriteQueueSize
+	headOpts.SamplesPerChunk = opts.SamplesPerChunk
 	headOpts.StripeSize = opts.StripeSize
 	headOpts.SeriesCallback = opts.SeriesLifecycleCallback
 	headOpts.EnableExemplarStorage = opts.EnableExemplarStorage
@@ -845,6 +855,7 @@ func open(dir string, l log.Logger, r prometheus.Registerer, opts *Options, rngs
 	if err != nil {
 		return nil, err
 	}
+	db.head.writeNotified = db.writeNotified
 
 	// Register metrics after assigning the head block.
 	db.metrics = newDBMetrics(db, r)
@@ -2074,6 +2085,12 @@ func (db *DB) CleanTombstones() (err error) {
 	return nil
 }
 
+func (db *DB) SetWriteNotified(wn wlog.WriteNotified) {
+	db.writeNotified = wn
+	// It's possible we already created the head struct, so we should also set the WN for that.
+	db.head.writeNotified = wn
+}
+
 func isBlockDir(fi fs.DirEntry) bool {
 	if !fi.IsDir() {
 		return false

tsdb/head.go

@@ -136,6 +136,8 @@ type Head struct {
 	stats *HeadStats
 	reg   prometheus.Registerer
 
+	writeNotified wlog.WriteNotified
+
 	memTruncationInProcess atomic.Bool
 }
 
@@ -166,6 +168,8 @@ type HeadOptions struct {
 	ChunkEndTimeVariance float64
 	ChunkWriteQueueSize  int
 
+	SamplesPerChunk int
+
 	// StripeSize sets the number of entries in the hash map, it must be a power of 2.
 	// A larger StripeSize will allocate more memory up-front, but will increase performance when handling a large number of series.
 	// A smaller StripeSize reduces the memory allocated, but can decrease performance with large number of series.
@@ -189,6 +193,8 @@ type HeadOptions struct {
 const (
 	// DefaultOutOfOrderCapMax is the default maximum size of an in-memory out-of-order chunk.
 	DefaultOutOfOrderCapMax int64 = 32
+	// DefaultSamplesPerChunk provides a default target number of samples per chunk.
+	DefaultSamplesPerChunk = 120
 )
 
 func DefaultHeadOptions() *HeadOptions {
@@ -199,6 +205,7 @@ func DefaultHeadOptions() *HeadOptions {
 		ChunkWriteBufferSize:          chunks.DefaultWriteBufferSize,
 		ChunkEndTimeVariance:          0,
 		ChunkWriteQueueSize:           chunks.DefaultWriteQueueSize,
+		SamplesPerChunk:               DefaultSamplesPerChunk,
 		StripeSize:                    DefaultStripeSize,
 		SeriesCallback:                &noopSeriesLifecycleCallback{},
 		IsolationDisabled:             defaultIsolationDisabled,
@@ -998,7 +1005,7 @@ func (h *Head) DisableNativeHistograms() {
 }
 
 // PostingsCardinalityStats returns top 10 highest cardinality stats By label and value names.
-func (h *Head) PostingsCardinalityStats(statsByLabelName string) *index.PostingsStats {
+func (h *Head) PostingsCardinalityStats(statsByLabelName string, limit int) *index.PostingsStats {
 	h.cardinalityMutex.Lock()
 	defer h.cardinalityMutex.Unlock()
 	currentTime := time.Duration(time.Now().Unix()) * time.Second
@@ -1009,7 +1016,7 @@ func (h *Head) PostingsCardinalityStats(statsByLabelName string) *index.Postings
 	if h.cardinalityCache != nil {
 		return h.cardinalityCache
 	}
-	h.cardinalityCache = h.postings.Stats(statsByLabelName)
+	h.cardinalityCache = h.postings.Stats(statsByLabelName, limit)
 	h.lastPostingsStatsCall = time.Duration(time.Now().Unix()) * time.Second
 
 	return h.cardinalityCache
@@ -1239,9 +1246,9 @@ func (h *Head) truncateWAL(mint int64) error {
 			return true
 		}
 		h.deletedMtx.Lock()
-		_, ok := h.deleted[id]
+		keepUntil, ok := h.deleted[id]
 		h.deletedMtx.Unlock()
-		return ok
+		return ok && keepUntil > last
 	}
 	h.metrics.checkpointCreationTotal.Inc()
 	if _, err = wlog.Checkpoint(h.logger, h.wal, first, last, keep, mint); err != nil {
@@ -1262,7 +1269,7 @@ func (h *Head) truncateWAL(mint int64) error {
 	// longer need to track deleted series that are before it.
 	h.deletedMtx.Lock()
 	for ref, segment := range h.deleted {
-		if segment < first {
+		if segment <= last {
 			delete(h.deleted, ref)
 		}
 	}
@@ -1349,12 +1356,12 @@ type Stats struct {
 
 // Stats returns important current HEAD statistics. Note that it is expensive to
 // calculate these.
-func (h *Head) Stats(statsByLabelName string) *Stats {
+func (h *Head) Stats(statsByLabelName string, limit int) *Stats {
 	return &Stats{
 		NumSeries:         h.NumSeries(),
 		MaxTime:           h.MaxTime(),
 		MinTime:           h.MinTime(),
-		IndexPostingStats: h.PostingsCardinalityStats(statsByLabelName),
+		IndexPostingStats: h.PostingsCardinalityStats(statsByLabelName, limit),
 	}
 }
 
@@ -1634,7 +1641,7 @@ func (h *Head) getOrCreate(hash uint64, lset labels.Labels) (*memSeries, bool, e
 
 func (h *Head) getOrCreateWithID(id chunks.HeadSeriesRef, hash uint64, lset labels.Labels) (*memSeries, bool, error) {
 	s, created, err := h.series.getOrSet(hash, lset, func() *memSeries {
-		return newMemSeries(lset, id, labels.StableHash(lset), h.opts.ChunkEndTimeVariance, h.opts.IsolationDisabled)
+		return newMemSeries(lset, id, labels.StableHash(lset), h.opts.ChunkEndTimeVariance, h.opts.IsolationDisabled, h.opts.SamplesPerChunk)
 	})
 	if err != nil {
 		return nil, false, err
@@ -1949,6 +1956,7 @@ type memSeries struct {
 	// to spread chunks writing across time. Doesn't apply to the last chunk of the chunk range. 0 to disable variance.
 	chunkEndTimeVariance float64
 
+	samplesPerChunk int   // Target number of samples per chunk.
 	nextAt          int64 // Timestamp at which to cut the next chunk.
 
 	// We keep the last value here (in addition to appending it to the chunk) so we can check for duplicates.
@@ -1977,13 +1985,14 @@ type memSeriesOOOFields struct {
 	firstOOOChunkID  chunks.HeadChunkID // HeadOOOChunkID for oooMmappedChunks[0].
 }
 
-func newMemSeries(lset labels.Labels, id chunks.HeadSeriesRef, shardHash uint64, chunkEndTimeVariance float64, isolationDisabled bool) *memSeries {
+func newMemSeries(lset labels.Labels, id chunks.HeadSeriesRef, shardHash uint64, chunkEndTimeVariance float64, isolationDisabled bool, samplesPerChunk int) *memSeries {
 	s := &memSeries{
 		lset:                 lset,
 		ref:                  id,
 		nextAt:               math.MinInt64,
 		chunkEndTimeVariance: chunkEndTimeVariance,
 		shardHash:            shardHash,
+		samplesPerChunk:      samplesPerChunk,
 	}
 	if !isolationDisabled {
 		s.txs = newTxRing(4)

tsdb/head_append.go

@@ -849,6 +849,10 @@ func (a *headAppender) Commit() (err error) {
 		return errors.Wrap(err, "write to WAL")
 	}
 
+	if a.head.writeNotified != nil {
+		a.head.writeNotified.Notify()
+	}
+
 	// No errors logging to WAL, so pass the exemplars along to the in memory storage.
 	for _, e := range a.exemplars {
 		s := a.head.series.getByID(chunks.HeadSeriesRef(e.ref))
@@ -1339,11 +1343,6 @@ func (s *memSeries) appendFloatHistogram(t int64, fh *histogram.FloatHistogram,
 func (s *memSeries) appendPreprocessor(
 	t int64, e chunkenc.Encoding, chunkDiskMapper chunkDiskMapper, chunkRange int64,
 ) (c *memChunk, sampleInOrder, chunkCreated bool) {
-	// Based on Gorilla white papers this offers near-optimal compression ratio
-	// so anything bigger that this has diminishing returns and increases
-	// the time range within which we have to decompress all samples.
-	const samplesPerChunk = 120
-
 	c = s.head()
 
 	if c == nil {
@@ -1380,7 +1379,7 @@ func (s *memSeries) appendPreprocessor(
 	// for this chunk that will try to make samples equally distributed within
 	// the remaining chunks in the current chunk range.
 	// At latest it must happen at the timestamp set when the chunk was cut.
-	if numSamples == samplesPerChunk/4 {
+	if numSamples == s.samplesPerChunk/4 {
 		maxNextAt := s.nextAt
 
 		s.nextAt = computeChunkEndTime(c.minTime, c.maxTime, maxNextAt)
@@ -1391,7 +1390,7 @@ func (s *memSeries) appendPreprocessor(
 	// Since we assume that the rate is higher, we're being conservative and cutting at 2*samplesPerChunk
 	// as we expect more chunks to come.
 	// Note that next chunk will have its nextAt recalculated for the new rate.
-	if t >= s.nextAt || numSamples >= samplesPerChunk*2 {
+	if t >= s.nextAt || numSamples >= s.samplesPerChunk*2 {
 		c = s.cutNewHeadChunk(t, e, chunkDiskMapper, chunkRange)
 		chunkCreated = true
 	}

tsdb/head_read.go

@@ -360,7 +360,7 @@ func (h *headChunkReader) chunk(meta chunks.Meta, copyLastChunk bool) (chunkenc.
 	}
 	s.Unlock()
 
-	return &safeChunk{
+	return &safeHeadChunk{
 		Chunk:    chk,
 		s:        s,
 		cid:      cid,
@@ -656,15 +656,15 @@ func (b boundedIterator) Seek(t int64) chunkenc.ValueType {
 	return b.Iterator.Seek(t)
 }
 
-// safeChunk makes sure that the chunk can be accessed without a race condition
+// safeHeadChunk makes sure that the chunk can be accessed without a race condition
-type safeChunk struct {
+type safeHeadChunk struct {
 	chunkenc.Chunk
 	s        *memSeries
 	cid      chunks.HeadChunkID
 	isoState *isolationState
 }
 
-func (c *safeChunk) Iterator(reuseIter chunkenc.Iterator) chunkenc.Iterator {
+func (c *safeHeadChunk) Iterator(reuseIter chunkenc.Iterator) chunkenc.Iterator {
 	c.s.Lock()
 	it := c.s.iterator(c.cid, c.Chunk, c.isoState, reuseIter)
 	c.s.Unlock()

tsdb/head_test.go

@@ -286,7 +286,7 @@ func BenchmarkLoadWAL(b *testing.B) {
 						for k := 0; k < c.batches*c.seriesPerBatch; k++ {
 							// Create one mmapped chunk per series, with one sample at the given time.
 							lbls := labels.Labels{}
-							s := newMemSeries(lbls, chunks.HeadSeriesRef(k)*101, labels.StableHash(lbls), 0, defaultIsolationDisabled)
+							s := newMemSeries(lbls, chunks.HeadSeriesRef(k)*101, labels.StableHash(lbls), 0, defaultIsolationDisabled, DefaultSamplesPerChunk)
 							s.append(c.mmappedChunkT, 42, 0, chunkDiskMapper, c.mmappedChunkT)
 							s.mmapCurrentHeadChunk(chunkDiskMapper)
 						}
@@ -809,7 +809,7 @@ func TestMemSeries_truncateChunks(t *testing.T) {
 	}
 
 	lbls := labels.FromStrings("a", "b")
-	s := newMemSeries(lbls, 1, labels.StableHash(lbls), 0, defaultIsolationDisabled)
+	s := newMemSeries(lbls, 1, labels.StableHash(lbls), 0, defaultIsolationDisabled, DefaultSamplesPerChunk)
 
 	for i := 0; i < 4000; i += 5 {
 		ok, _ := s.append(int64(i), float64(i), 0, chunkDiskMapper, chunkRange)
@@ -1341,7 +1341,7 @@ func TestMemSeries_append(t *testing.T) {
 	const chunkRange = 500
 
 	lbls := labels.Labels{}
-	s := newMemSeries(lbls, 1, labels.StableHash(lbls), 0, defaultIsolationDisabled)
+	s := newMemSeries(lbls, 1, labels.StableHash(lbls), 0, defaultIsolationDisabled, DefaultSamplesPerChunk)
 
 	// Add first two samples at the very end of a chunk range and the next two
 	// on and after it.
@@ -1396,7 +1396,7 @@ func TestMemSeries_appendHistogram(t *testing.T) {
 	chunkRange := int64(1000)
 
 	lbls := labels.Labels{}
-	s := newMemSeries(lbls, 1, labels.StableHash(lbls), 0, defaultIsolationDisabled)
+	s := newMemSeries(lbls, 1, labels.StableHash(lbls), 0, defaultIsolationDisabled, DefaultSamplesPerChunk)
 
 	histograms := tsdbutil.GenerateTestHistograms(4)
 	histogramWithOneMoreBucket := histograms[3].Copy()
@@ -1453,7 +1453,7 @@ func TestMemSeries_append_atVariableRate(t *testing.T) {
 	chunkRange := DefaultBlockDuration
 
 	lbls := labels.Labels{}
-	s := newMemSeries(lbls, 1, labels.StableHash(lbls), 0, defaultIsolationDisabled)
+	s := newMemSeries(lbls, 1, labels.StableHash(lbls), 0, defaultIsolationDisabled, DefaultSamplesPerChunk)
 
 	// At this slow rate, we will fill the chunk in two block durations.
 	slowRate := (DefaultBlockDuration * 2) / samplesPerChunk
@@ -2677,7 +2677,7 @@ func TestIteratorSeekIntoBuffer(t *testing.T) {
 	const chunkRange = 500
 
 	lbls := labels.Labels{}
-	s := newMemSeries(lbls, 1, labels.StableHash(lbls), 0, defaultIsolationDisabled)
+	s := newMemSeries(lbls, 1, labels.StableHash(lbls), 0, defaultIsolationDisabled, DefaultSamplesPerChunk)
 
 	for i := 0; i < 7; i++ {
 		ok, _ := s.append(int64(i), float64(i), 0, chunkDiskMapper, chunkRange)

tsdb/index/postings.go

@@ -156,10 +156,8 @@ type PostingsStats struct {
 }
 
 // Stats calculates the cardinality statistics from postings.
-func (p *MemPostings) Stats(label string) *PostingsStats {
+func (p *MemPostings) Stats(label string, limit int) *PostingsStats {
-	const maxNumOfRecords = 10
 	var size uint64
-
 	p.mtx.RLock()
 
 	metrics := &maxHeap{}
@@ -168,10 +166,10 @@ func (p *MemPostings) Stats(label string) *PostingsStats {
 	labelValuePairs := &maxHeap{}
 	numLabelPairs := 0
 
-	metrics.init(maxNumOfRecords)
+	metrics.init(limit)
-	labels.init(maxNumOfRecords)
+	labels.init(limit)
-	labelValueLength.init(maxNumOfRecords)
+	labelValueLength.init(limit)
-	labelValuePairs.init(maxNumOfRecords)
+	labelValuePairs.init(limit)
 
 	for n, e := range p.m {
 		if n == "" {
@@ -184,8 +182,9 @@ func (p *MemPostings) Stats(label string) *PostingsStats {
 			if n == label {
 				metrics.push(Stat{Name: name, Count: uint64(len(values))})
 			}
-			labelValuePairs.push(Stat{Name: n + "=" + name, Count: uint64(len(values))})
+			seriesCnt := uint64(len(values))
-			size += uint64(len(name))
+			labelValuePairs.push(Stat{Name: n + "=" + name, Count: seriesCnt})
+			size += uint64(len(name)) * seriesCnt
 		}
 		labelValueLength.push(Stat{Name: n, Count: size})
 	}

tsdb/index/postings_test.go

@@ -912,10 +912,39 @@ func BenchmarkPostings_Stats(b *testing.B) {
 	}
 	b.ResetTimer()
 	for n := 0; n < b.N; n++ {
-		p.Stats("__name__")
+		p.Stats("__name__", 10)
 	}
 }
 
+func TestMemPostingsStats(t *testing.T) {
+	// create a new MemPostings
+	p := NewMemPostings()
+
+	// add some postings to the MemPostings
+	p.Add(1, labels.FromStrings("label", "value1"))
+	p.Add(1, labels.FromStrings("label", "value2"))
+	p.Add(1, labels.FromStrings("label", "value3"))
+	p.Add(2, labels.FromStrings("label", "value1"))
+
+	// call the Stats method to calculate the cardinality statistics
+	stats := p.Stats("label", 10)
+
+	// assert that the expected statistics were calculated
+	require.Equal(t, uint64(2), stats.CardinalityMetricsStats[0].Count)
+	require.Equal(t, "value1", stats.CardinalityMetricsStats[0].Name)
+
+	require.Equal(t, uint64(3), stats.CardinalityLabelStats[0].Count)
+	require.Equal(t, "label", stats.CardinalityLabelStats[0].Name)
+
+	require.Equal(t, uint64(24), stats.LabelValueStats[0].Count)
+	require.Equal(t, "label", stats.LabelValueStats[0].Name)
+
+	require.Equal(t, uint64(2), stats.LabelValuePairsStats[0].Count)
+	require.Equal(t, "label=value1", stats.LabelValuePairsStats[0].Name)
+
+	require.Equal(t, 3, stats.NumLabelPairs)
+}
+
 func TestMemPostings_Delete(t *testing.T) {
 	p := NewMemPostings()
 	p.Add(1, labels.FromStrings("lbl1", "a"))

tsdb/querier.go

@@ -310,6 +310,22 @@ func postingsForMatcher(ix IndexPostingsReader, m *labels.Matcher) (index.Postin
 
 // inversePostingsForMatcher returns the postings for the series with the label name set but not matching the matcher.
 func inversePostingsForMatcher(ix IndexPostingsReader, m *labels.Matcher) (index.Postings, error) {
+	// Fast-path for MatchNotRegexp matching.
+	// Inverse of a MatchNotRegexp is MatchRegexp (double negation).
+	// Fast-path for set matching.
+	if m.Type == labels.MatchNotRegexp {
+		setMatches := m.SetMatches()
+		if len(setMatches) > 0 {
+			return ix.Postings(m.Name, setMatches...)
+		}
+	}
+
+	// Fast-path for MatchNotEqual matching.
+	// Inverse of a MatchNotEqual is MatchEqual (double negation).
+	if m.Type == labels.MatchNotEqual {
+		return ix.Postings(m.Name, m.Value)
+	}
+
 	vals, err := ix.LabelValues(m.Name)
 	if err != nil {
 		return nil, err
@@ -746,14 +762,35 @@ func (p *populateWithDelChunkSeriesIterator) Next() bool {
 		if app, err = newChunk.Appender(); err != nil {
 			break
 		}
-		if hc, ok := p.currChkMeta.Chunk.(*chunkenc.HistogramChunk); ok {
+
+		switch hc := p.currChkMeta.Chunk.(type) {
+		case *chunkenc.HistogramChunk:
 			newChunk.(*chunkenc.HistogramChunk).SetCounterResetHeader(hc.GetCounterResetHeader())
+		case *safeHeadChunk:
+			if unwrapped, ok := hc.Chunk.(*chunkenc.HistogramChunk); ok {
+				newChunk.(*chunkenc.HistogramChunk).SetCounterResetHeader(unwrapped.GetCounterResetHeader())
+			} else {
+				err = fmt.Errorf("internal error, could not unwrap safeHeadChunk to histogram chunk: %T", hc.Chunk)
 			}
+		default:
+			err = fmt.Errorf("internal error, unknown chunk type %T when expecting histogram", p.currChkMeta.Chunk)
+		}
+		if err != nil {
+			break
+		}
+
 		var h *histogram.Histogram
 		t, h = p.currDelIter.AtHistogram()
 		p.curr.MinTime = t
 
+		// Detect missing gauge reset hint.
+		if h.CounterResetHint == histogram.GaugeType && newChunk.(*chunkenc.HistogramChunk).GetCounterResetHeader() != chunkenc.GaugeType {
+			err = fmt.Errorf("found gauge histogram in non gauge chunk")
+			break
+		}
+
 		app.AppendHistogram(t, h)
+
 		for vt := p.currDelIter.Next(); vt != chunkenc.ValNone; vt = p.currDelIter.Next() {
 			if vt != chunkenc.ValHistogram {
 				err = fmt.Errorf("found value type %v in histogram chunk", vt)
@@ -762,6 +799,20 @@ func (p *populateWithDelChunkSeriesIterator) Next() bool {
 			t, h = p.currDelIter.AtHistogram()
 
 			// Defend against corrupted chunks.
+			if h.CounterResetHint == histogram.GaugeType {
+				pI, nI, bpI, bnI, _, _, okToAppend := app.(*chunkenc.HistogramAppender).AppendableGauge(h)
+				if !okToAppend {
+					err = errors.New("unable to append histogram due to unexpected schema change")
+					break
+				}
+				if len(pI)+len(nI)+len(bpI)+len(bnI) > 0 {
+					err = fmt.Errorf(
+						"bucket layout has changed unexpectedly: forward %d positive, %d negative, backward %d positive %d negative bucket interjections required",
+						len(pI), len(nI), len(bpI), len(bnI),
+					)
+					break
+				}
+			} else {
 				pI, nI, okToAppend, counterReset := app.(*chunkenc.HistogramAppender).Appendable(h)
 				if len(pI)+len(nI) > 0 {
 					err = fmt.Errorf(
@@ -778,7 +829,7 @@ func (p *populateWithDelChunkSeriesIterator) Next() bool {
 					err = errors.New("unable to append histogram due to unexpected schema change")
 					break
 				}
-
+			}
 			app.AppendHistogram(t, h)
 		}
 	case chunkenc.ValFloat:
@@ -803,14 +854,35 @@ func (p *populateWithDelChunkSeriesIterator) Next() bool {
 		if app, err = newChunk.Appender(); err != nil {
 			break
 		}
-		if hc, ok := p.currChkMeta.Chunk.(*chunkenc.FloatHistogramChunk); ok {
+
+		switch hc := p.currChkMeta.Chunk.(type) {
+		case *chunkenc.FloatHistogramChunk:
 			newChunk.(*chunkenc.FloatHistogramChunk).SetCounterResetHeader(hc.GetCounterResetHeader())
+		case *safeHeadChunk:
+			if unwrapped, ok := hc.Chunk.(*chunkenc.FloatHistogramChunk); ok {
+				newChunk.(*chunkenc.FloatHistogramChunk).SetCounterResetHeader(unwrapped.GetCounterResetHeader())
+			} else {
+				err = fmt.Errorf("internal error, could not unwrap safeHeadChunk to float histogram chunk: %T", hc.Chunk)
 			}
+		default:
+			err = fmt.Errorf("internal error, unknown chunk type %T when expecting float histogram", p.currChkMeta.Chunk)
+		}
+		if err != nil {
+			break
+		}
+
 		var h *histogram.FloatHistogram
 		t, h = p.currDelIter.AtFloatHistogram()
 		p.curr.MinTime = t
 
+		// Detect missing gauge reset hint.
+		if h.CounterResetHint == histogram.GaugeType && newChunk.(*chunkenc.FloatHistogramChunk).GetCounterResetHeader() != chunkenc.GaugeType {
+			err = fmt.Errorf("found float gauge histogram in non gauge chunk")
+			break
+		}
+
 		app.AppendFloatHistogram(t, h)
+
 		for vt := p.currDelIter.Next(); vt != chunkenc.ValNone; vt = p.currDelIter.Next() {
 			if vt != chunkenc.ValFloatHistogram {
 				err = fmt.Errorf("found value type %v in histogram chunk", vt)
@@ -819,6 +891,20 @@ func (p *populateWithDelChunkSeriesIterator) Next() bool {
 			t, h = p.currDelIter.AtFloatHistogram()
 
 			// Defend against corrupted chunks.
+			if h.CounterResetHint == histogram.GaugeType {
+				pI, nI, bpI, bnI, _, _, okToAppend := app.(*chunkenc.FloatHistogramAppender).AppendableGauge(h)
+				if !okToAppend {
+					err = errors.New("unable to append histogram due to unexpected schema change")
+					break
+				}
+				if len(pI)+len(nI)+len(bpI)+len(bnI) > 0 {
+					err = fmt.Errorf(
+						"bucket layout has changed unexpectedly: forward %d positive, %d negative, backward %d positive %d negative bucket interjections required",
+						len(pI), len(nI), len(bpI), len(bnI),
+					)
+					break
+				}
+			} else {
 				pI, nI, okToAppend, counterReset := app.(*chunkenc.FloatHistogramAppender).Appendable(h)
 				if len(pI)+len(nI) > 0 {
 					err = fmt.Errorf(
@@ -835,6 +921,7 @@ func (p *populateWithDelChunkSeriesIterator) Next() bool {
 					err = errors.New("unable to append histogram due to unexpected schema change")
 					break
 				}
+			}
 
 			app.AppendFloatHistogram(t, h)
 		}

tsdb/querier_bench_test.go

@@ -116,6 +116,7 @@ func benchmarkPostingsForMatchers(b *testing.B, ir IndexReader) {
 	iCharSet := labels.MustNewMatcher(labels.MatchRegexp, "i", "1[0-9]")
 	iAlternate := labels.MustNewMatcher(labels.MatchRegexp, "i", "(1|2|3|4|5|6|20|55)")
 	iXYZ := labels.MustNewMatcher(labels.MatchRegexp, "i", "X|Y|Z")
+	iNotXYZ := labels.MustNewMatcher(labels.MatchNotRegexp, "i", "X|Y|Z")
 	cases := []struct {
 		name     string
 		matchers []*labels.Matcher
@@ -126,6 +127,7 @@ func benchmarkPostingsForMatchers(b *testing.B, ir IndexReader) {
 		{`n="X",j="foo"`, []*labels.Matcher{nX, jFoo}},
 		{`j="foo",n="1"`, []*labels.Matcher{jFoo, n1}},
 		{`n="1",j!="foo"`, []*labels.Matcher{n1, jNotFoo}},
+		{`n="1",i!="2"`, []*labels.Matcher{n1, iNot2}},
 		{`n="X",j!="foo"`, []*labels.Matcher{nX, jNotFoo}},
 		{`i=~"1[0-9]",j=~"foo|bar"`, []*labels.Matcher{iCharSet, jFooBar}},
 		{`j=~"foo|bar"`, []*labels.Matcher{jFooBar}},
@@ -133,6 +135,7 @@ func benchmarkPostingsForMatchers(b *testing.B, ir IndexReader) {
 		{`j=~"X.+"`, []*labels.Matcher{jXplus}},
 		{`i=~"(1|2|3|4|5|6|20|55)"`, []*labels.Matcher{iAlternate}},
 		{`i=~"X|Y|Z"`, []*labels.Matcher{iXYZ}},
+		{`i!~"X|Y|Z"`, []*labels.Matcher{iNotXYZ}},
 		{`i=~".*"`, []*labels.Matcher{iStar}},
 		{`i=~"1.*"`, []*labels.Matcher{i1Star}},
 		{`i=~".*1"`, []*labels.Matcher{iStar1}},
@@ -148,6 +151,7 @@ func benchmarkPostingsForMatchers(b *testing.B, ir IndexReader) {
 		{`n="1",i!="",j=~"X.+"`, []*labels.Matcher{n1, iNotEmpty, jXplus}},
 		{`n="1",i!="",j=~"XXX|YYY"`, []*labels.Matcher{n1, iNotEmpty, jXXXYYY}},
 		{`n="1",i=~"X|Y|Z",j="foo"`, []*labels.Matcher{n1, iXYZ, jFoo}},
+		{`n="1",i!~"X|Y|Z",j="foo"`, []*labels.Matcher{n1, iNotXYZ, jFoo}},
 		{`n="1",i=~".+",j="foo"`, []*labels.Matcher{n1, iPlus, jFoo}},
 		{`n="1",i=~"1.+",j="foo"`, []*labels.Matcher{n1, i1Plus, jFoo}},
 		{`n="1",i=~".*1.*",j="foo"`, []*labels.Matcher{n1, iStar1Star, jFoo}},

tsdb/querier_test.go

@@ -29,6 +29,7 @@ import (
 	"github.com/pkg/errors"
 	"github.com/stretchr/testify/require"
 
+	"github.com/prometheus/prometheus/model/histogram"
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/storage"
 	"github.com/prometheus/prometheus/tsdb/chunkenc"
@@ -541,6 +542,46 @@ func TestBlockQuerier_AgainstHeadWithOpenChunks(t *testing.T) {
 	}
 }
 
+func TestBlockQuerier_TrimmingDoesNotModifyOriginalTombstoneIntervals(t *testing.T) {
+	c := blockQuerierTestCase{
+		mint: 2,
+		maxt: 6,
+		ms:   []*labels.Matcher{labels.MustNewMatcher(labels.MatchRegexp, "a", "a")},
+		exp: newMockSeriesSet([]storage.Series{
+			storage.NewListSeries(labels.FromStrings("a", "a"),
+				[]tsdbutil.Sample{sample{3, 4, nil, nil}, sample{5, 2, nil, nil}, sample{6, 3, nil, nil}},
+			),
+			storage.NewListSeries(labels.FromStrings("a", "a", "b", "b"),
+				[]tsdbutil.Sample{sample{3, 3, nil, nil}, sample{5, 3, nil, nil}, sample{6, 6, nil, nil}},
+			),
+		}),
+		expChks: newMockChunkSeriesSet([]storage.ChunkSeries{
+			storage.NewListChunkSeriesFromSamples(labels.FromStrings("a", "a"),
+				[]tsdbutil.Sample{sample{3, 4, nil, nil}}, []tsdbutil.Sample{sample{5, 2, nil, nil}, sample{6, 3, nil, nil}},
+			),
+			storage.NewListChunkSeriesFromSamples(labels.FromStrings("a", "a", "b", "b"),
+				[]tsdbutil.Sample{sample{3, 3, nil, nil}}, []tsdbutil.Sample{sample{5, 3, nil, nil}, sample{6, 6, nil, nil}},
+			),
+		}),
+	}
+	ir, cr, _, _ := createIdxChkReaders(t, testData)
+	stones := tombstones.NewMemTombstones()
+	p, err := ir.Postings("a", "a")
+	require.NoError(t, err)
+	refs, err := index.ExpandPostings(p)
+	require.NoError(t, err)
+	for _, ref := range refs {
+		stones.AddInterval(ref, tombstones.Interval{Mint: 1, Maxt: 2})
+	}
+	testBlockQuerier(t, c, ir, cr, stones)
+	for _, ref := range refs {
+		intervals, err := stones.Get(ref)
+		require.NoError(t, err)
+		// Without copy, the intervals could be [math.MinInt64, 2].
+		require.Equal(t, tombstones.Intervals{{Mint: 1, Maxt: 2}}, intervals)
+	}
+}
+
 var testData = []seriesSamples{
 	{
 		lset: map[string]string{"a": "a"},
@@ -907,6 +948,202 @@ func TestPopulateWithTombSeriesIterators(t *testing.T) {
 				sample{3, 5, nil, nil}, sample{6, 1, nil, nil}, sample{7, 89, nil, nil},
 			},
 		},
+		{
+			name: "one histogram chunk",
+			chks: [][]tsdbutil.Sample{
+				{
+					sample{1, 0, tsdbutil.GenerateTestHistogram(1), nil},
+					sample{2, 0, tsdbutil.GenerateTestHistogram(2), nil},
+					sample{3, 0, tsdbutil.GenerateTestHistogram(3), nil},
+					sample{6, 0, tsdbutil.GenerateTestHistogram(6), nil},
+				},
+			},
+			expected: []tsdbutil.Sample{
+				sample{1, 0, tsdbutil.GenerateTestHistogram(1), nil},
+				sample{2, 0, tsdbutil.SetHistogramNotCounterReset(tsdbutil.GenerateTestHistogram(2)), nil},
+				sample{3, 0, tsdbutil.SetHistogramNotCounterReset(tsdbutil.GenerateTestHistogram(3)), nil},
+				sample{6, 0, tsdbutil.SetHistogramNotCounterReset(tsdbutil.GenerateTestHistogram(6)), nil},
+			},
+			expectedChks: []chunks.Meta{
+				tsdbutil.ChunkFromSamples([]tsdbutil.Sample{
+					sample{1, 0, tsdbutil.GenerateTestHistogram(1), nil},
+					sample{2, 0, tsdbutil.SetHistogramNotCounterReset(tsdbutil.GenerateTestHistogram(2)), nil},
+					sample{3, 0, tsdbutil.SetHistogramNotCounterReset(tsdbutil.GenerateTestHistogram(3)), nil},
+					sample{6, 0, tsdbutil.SetHistogramNotCounterReset(tsdbutil.GenerateTestHistogram(6)), nil},
+				}),
+			},
+		},
+		{
+			name: "one histogram chunk intersect with deletion interval",
+			chks: [][]tsdbutil.Sample{
+				{
+					sample{1, 0, tsdbutil.GenerateTestHistogram(1), nil},
+					sample{2, 0, tsdbutil.GenerateTestHistogram(2), nil},
+					sample{3, 0, tsdbutil.GenerateTestHistogram(3), nil},
+					sample{6, 0, tsdbutil.GenerateTestHistogram(6), nil},
+				},
+			},
+			intervals: tombstones.Intervals{{Mint: 5, Maxt: 20}},
+			expected: []tsdbutil.Sample{
+				sample{1, 0, tsdbutil.GenerateTestHistogram(1), nil},
+				sample{2, 0, tsdbutil.SetHistogramNotCounterReset(tsdbutil.GenerateTestHistogram(2)), nil},
+				sample{3, 0, tsdbutil.SetHistogramNotCounterReset(tsdbutil.GenerateTestHistogram(3)), nil},
+			},
+			expectedChks: []chunks.Meta{
+				tsdbutil.ChunkFromSamples([]tsdbutil.Sample{
+					sample{1, 0, tsdbutil.GenerateTestHistogram(1), nil},
+					sample{2, 0, tsdbutil.SetHistogramNotCounterReset(tsdbutil.GenerateTestHistogram(2)), nil},
+					sample{3, 0, tsdbutil.SetHistogramNotCounterReset(tsdbutil.GenerateTestHistogram(3)), nil},
+				}),
+			},
+		},
+		{
+			name: "one float histogram chunk",
+			chks: [][]tsdbutil.Sample{
+				{
+					sample{1, 0, nil, tsdbutil.GenerateTestFloatHistogram(1)},
+					sample{2, 0, nil, tsdbutil.GenerateTestFloatHistogram(2)},
+					sample{3, 0, nil, tsdbutil.GenerateTestFloatHistogram(3)},
+					sample{6, 0, nil, tsdbutil.GenerateTestFloatHistogram(6)},
+				},
+			},
+			expected: []tsdbutil.Sample{
+				sample{1, 0, nil, tsdbutil.GenerateTestFloatHistogram(1)},
+				sample{2, 0, nil, tsdbutil.SetFloatHistogramNotCounterReset(tsdbutil.GenerateTestFloatHistogram(2))},
+				sample{3, 0, nil, tsdbutil.SetFloatHistogramNotCounterReset(tsdbutil.GenerateTestFloatHistogram(3))},
+				sample{6, 0, nil, tsdbutil.SetFloatHistogramNotCounterReset(tsdbutil.GenerateTestFloatHistogram(6))},
+			},
+			expectedChks: []chunks.Meta{
+				tsdbutil.ChunkFromSamples([]tsdbutil.Sample{
+					sample{1, 0, nil, tsdbutil.GenerateTestFloatHistogram(1)},
+					sample{2, 0, nil, tsdbutil.SetFloatHistogramNotCounterReset(tsdbutil.GenerateTestFloatHistogram(2))},
+					sample{3, 0, nil, tsdbutil.SetFloatHistogramNotCounterReset(tsdbutil.GenerateTestFloatHistogram(3))},
+					sample{6, 0, nil, tsdbutil.SetFloatHistogramNotCounterReset(tsdbutil.GenerateTestFloatHistogram(6))},
+				}),
+			},
+		},
+		{
+			name: "one float histogram chunk intersect with deletion interval",
+			chks: [][]tsdbutil.Sample{
+				{
+					sample{1, 0, nil, tsdbutil.GenerateTestFloatHistogram(1)},
+					sample{2, 0, nil, tsdbutil.GenerateTestFloatHistogram(2)},
+					sample{3, 0, nil, tsdbutil.GenerateTestFloatHistogram(3)},
+					sample{6, 0, nil, tsdbutil.GenerateTestFloatHistogram(6)},
+				},
+			},
+			intervals: tombstones.Intervals{{Mint: 5, Maxt: 20}},
+			expected: []tsdbutil.Sample{
+				sample{1, 0, nil, tsdbutil.GenerateTestFloatHistogram(1)},
+				sample{2, 0, nil, tsdbutil.SetFloatHistogramNotCounterReset(tsdbutil.GenerateTestFloatHistogram(2))},
+				sample{3, 0, nil, tsdbutil.SetFloatHistogramNotCounterReset(tsdbutil.GenerateTestFloatHistogram(3))},
+			},
+			expectedChks: []chunks.Meta{
+				tsdbutil.ChunkFromSamples([]tsdbutil.Sample{
+					sample{1, 0, nil, tsdbutil.GenerateTestFloatHistogram(1)},
+					sample{2, 0, nil, tsdbutil.SetFloatHistogramNotCounterReset(tsdbutil.GenerateTestFloatHistogram(2))},
+					sample{3, 0, nil, tsdbutil.SetFloatHistogramNotCounterReset(tsdbutil.GenerateTestFloatHistogram(3))},
+				}),
+			},
+		},
+		{
+			name: "one gauge histogram chunk",
+			chks: [][]tsdbutil.Sample{
+				{
+					sample{1, 0, tsdbutil.GenerateTestGaugeHistogram(1), nil},
+					sample{2, 0, tsdbutil.GenerateTestGaugeHistogram(2), nil},
+					sample{3, 0, tsdbutil.GenerateTestGaugeHistogram(3), nil},
+					sample{6, 0, tsdbutil.GenerateTestGaugeHistogram(6), nil},
+				},
+			},
+			expected: []tsdbutil.Sample{
+				sample{1, 0, tsdbutil.GenerateTestGaugeHistogram(1), nil},
+				sample{2, 0, tsdbutil.GenerateTestGaugeHistogram(2), nil},
+				sample{3, 0, tsdbutil.GenerateTestGaugeHistogram(3), nil},
+				sample{6, 0, tsdbutil.GenerateTestGaugeHistogram(6), nil},
+			},
+			expectedChks: []chunks.Meta{
+				tsdbutil.ChunkFromSamples([]tsdbutil.Sample{
+					sample{1, 0, tsdbutil.GenerateTestGaugeHistogram(1), nil},
+					sample{2, 0, tsdbutil.GenerateTestGaugeHistogram(2), nil},
+					sample{3, 0, tsdbutil.GenerateTestGaugeHistogram(3), nil},
+					sample{6, 0, tsdbutil.GenerateTestGaugeHistogram(6), nil},
+				}),
+			},
+		},
+		{
+			name: "one gauge histogram chunk intersect with deletion interval",
+			chks: [][]tsdbutil.Sample{
+				{
+					sample{1, 0, tsdbutil.GenerateTestGaugeHistogram(1), nil},
+					sample{2, 0, tsdbutil.GenerateTestGaugeHistogram(2), nil},
+					sample{3, 0, tsdbutil.GenerateTestGaugeHistogram(3), nil},
+					sample{6, 0, tsdbutil.GenerateTestGaugeHistogram(6), nil},
+				},
+			},
+			intervals: tombstones.Intervals{{Mint: 5, Maxt: 20}},
+			expected: []tsdbutil.Sample{
+				sample{1, 0, tsdbutil.GenerateTestGaugeHistogram(1), nil},
+				sample{2, 0, tsdbutil.GenerateTestGaugeHistogram(2), nil},
+				sample{3, 0, tsdbutil.GenerateTestGaugeHistogram(3), nil},
+			},
+			expectedChks: []chunks.Meta{
+				tsdbutil.ChunkFromSamples([]tsdbutil.Sample{
+					sample{1, 0, tsdbutil.GenerateTestGaugeHistogram(1), nil},
+					sample{2, 0, tsdbutil.GenerateTestGaugeHistogram(2), nil},
+					sample{3, 0, tsdbutil.GenerateTestGaugeHistogram(3), nil},
+				}),
+			},
+		},
+		{
+			name: "one gauge float histogram",
+			chks: [][]tsdbutil.Sample{
+				{
+					sample{1, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(1)},
+					sample{2, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(2)},
+					sample{3, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(3)},
+					sample{6, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(6)},
+				},
+			},
+			expected: []tsdbutil.Sample{
+				sample{1, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(1)},
+				sample{2, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(2)},
+				sample{3, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(3)},
+				sample{6, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(6)},
+			},
+			expectedChks: []chunks.Meta{
+				tsdbutil.ChunkFromSamples([]tsdbutil.Sample{
+					sample{1, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(1)},
+					sample{2, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(2)},
+					sample{3, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(3)},
+					sample{6, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(6)},
+				}),
+			},
+		},
+		{
+			name: "one gauge float histogram chunk intersect with deletion interval",
+			chks: [][]tsdbutil.Sample{
+				{
+					sample{1, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(1)},
+					sample{2, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(2)},
+					sample{3, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(3)},
+					sample{6, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(6)},
+				},
+			},
+			intervals: tombstones.Intervals{{Mint: 5, Maxt: 20}},
+			expected: []tsdbutil.Sample{
+				sample{1, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(1)},
+				sample{2, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(2)},
+				sample{3, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(3)},
+			},
+			expectedChks: []chunks.Meta{
+				tsdbutil.ChunkFromSamples([]tsdbutil.Sample{
+					sample{1, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(1)},
+					sample{2, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(2)},
+					sample{3, 0, nil, tsdbutil.GenerateTestGaugeFloatHistogram(3)},
+				}),
+			},
+		},
 	}
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
@@ -1820,6 +2057,19 @@ func TestPostingsForMatchers(t *testing.T) {
 				labels.FromStrings("n", "2.5"),
 			},
 		},
+		{
+			matchers: []*labels.Matcher{labels.MustNewMatcher(labels.MatchNotRegexp, "n", "1")},
+			exp: []labels.Labels{
+				labels.FromStrings("n", "2"),
+				labels.FromStrings("n", "2.5"),
+			},
+		},
+		{
+			matchers: []*labels.Matcher{labels.MustNewMatcher(labels.MatchNotRegexp, "n", "1|2.5")},
+			exp: []labels.Labels{
+				labels.FromStrings("n", "2"),
+			},
+		},
 		{
 			matchers: []*labels.Matcher{labels.MustNewMatcher(labels.MatchEqual, "n", "1"), labels.MustNewMatcher(labels.MatchNotRegexp, "i", "^a$")},
 			exp: []labels.Labels{
@@ -1909,6 +2159,14 @@ func TestPostingsForMatchers(t *testing.T) {
 	require.NoError(t, err)
 
 	for _, c := range cases {
+		name := ""
+		for i, matcher := range c.matchers {
+			if i > 0 {
+				name += ","
+			}
+			name += matcher.String()
+		}
+		t.Run(name, func(t *testing.T) {
 			exp := map[string]struct{}{}
 			for _, l := range c.exp {
 				exp[l.String()] = struct{}{}
@@ -1930,6 +2188,7 @@ func TestPostingsForMatchers(t *testing.T) {
 			if len(exp) != 0 {
 				t.Errorf("Evaluating %v, missing results %+v", c.matchers, exp)
 			}
+		})
 	}
 }
 
@@ -2376,3 +2635,80 @@ func BenchmarkHeadQuerier(b *testing.B) {
 		require.NoError(b, ss.Err())
 	}
 }
+
+// This is a regression test for the case where gauge histograms were not handled by
+// populateWithDelChunkSeriesIterator correctly.
+func TestQueryWithDeletedHistograms(t *testing.T) {
+	testcases := map[string]func(int) (*histogram.Histogram, *histogram.FloatHistogram){
+		"intCounter": func(i int) (*histogram.Histogram, *histogram.FloatHistogram) {
+			return tsdbutil.GenerateTestHistogram(i), nil
+		},
+		"intgauge": func(i int) (*histogram.Histogram, *histogram.FloatHistogram) {
+			return tsdbutil.GenerateTestGaugeHistogram(rand.Int() % 1000), nil
+		},
+		"floatCounter": func(i int) (*histogram.Histogram, *histogram.FloatHistogram) {
+			return nil, tsdbutil.GenerateTestFloatHistogram(i)
+		},
+		"floatGauge": func(i int) (*histogram.Histogram, *histogram.FloatHistogram) {
+			return nil, tsdbutil.GenerateTestGaugeFloatHistogram(rand.Int() % 1000)
+		},
+	}
+
+	for name, tc := range testcases {
+		t.Run(name, func(t *testing.T) {
+			db := openTestDB(t, nil, nil)
+			defer func() {
+				require.NoError(t, db.Close())
+			}()
+
+			db.EnableNativeHistograms()
+			appender := db.Appender(context.Background())
+
+			var (
+				err       error
+				seriesRef storage.SeriesRef
+			)
+			lbs := labels.FromStrings("__name__", "test", "type", name)
+
+			for i := 0; i < 100; i++ {
+				h, fh := tc(i)
+				seriesRef, err = appender.AppendHistogram(seriesRef, lbs, int64(i), h, fh)
+				require.NoError(t, err)
+			}
+
+			err = appender.Commit()
+			require.NoError(t, err)
+
+			matcher, err := labels.NewMatcher(labels.MatchEqual, "__name__", "test")
+			require.NoError(t, err)
+
+			// Delete the last 20.
+			err = db.Delete(80, 100, matcher)
+			require.NoError(t, err)
+
+			chunkQuerier, err := db.ChunkQuerier(context.Background(), 0, 100)
+			require.NoError(t, err)
+
+			css := chunkQuerier.Select(false, nil, matcher)
+
+			seriesCount := 0
+			for css.Next() {
+				seriesCount++
+				series := css.At()
+
+				sampleCount := 0
+				it := series.Iterator(nil)
+				for it.Next() {
+					chk := it.At()
+					for cit := chk.Chunk.Iterator(nil); cit.Next() != chunkenc.ValNone; {
+						sampleCount++
+					}
+				}
+				require.NoError(t, it.Err())
+				require.Equal(t, 80, sampleCount)
+			}
+			require.NoError(t, css.Err())
+			require.Equal(t, 1, seriesCount)
+		})
+	}
+}

tsdb/tombstones/tombstones.go

@@ -18,6 +18,7 @@ import (
 	"fmt"
 	"hash"
 	"hash/crc32"
+	"math"
 	"os"
 	"path/filepath"
 	"sort"
@@ -252,7 +253,14 @@ func NewTestMemTombstones(intervals []Intervals) *MemTombstones {
 func (t *MemTombstones) Get(ref storage.SeriesRef) (Intervals, error) {
 	t.mtx.RLock()
 	defer t.mtx.RUnlock()
-	return t.intvlGroups[ref], nil
+	intervals, ok := t.intvlGroups[ref]
+	if !ok {
+		return nil, nil
+	}
+	// Make a copy to avoid race.
+	res := make(Intervals, len(intervals))
+	copy(res, intervals)
+	return res, nil
 }
 
 func (t *MemTombstones) DeleteTombstones(refs map[storage.SeriesRef]struct{}) {
@@ -349,18 +357,24 @@ func (in Intervals) Add(n Interval) Intervals {
 	// Find min and max indexes of intervals that overlap with the new interval.
 	// Intervals are closed [t1, t2] and t is discreet, so if neighbour intervals are 1 step difference
 	// to the new one, we can merge those together.
-	mini := sort.Search(len(in), func(i int) bool { return in[i].Maxt >= n.Mint-1 })
+	mini := 0
+	if n.Mint != math.MinInt64 { // Avoid overflow.
+		mini = sort.Search(len(in), func(i int) bool { return in[i].Maxt >= n.Mint-1 })
 		if mini == len(in) {
 			return append(in, n)
 		}
+	}
 
-	maxi := sort.Search(len(in)-mini, func(i int) bool { return in[mini+i].Mint > n.Maxt+1 })
+	maxi := len(in)
+	if n.Maxt != math.MaxInt64 { // Avoid overflow.
+		maxi = sort.Search(len(in)-mini, func(i int) bool { return in[mini+i].Mint > n.Maxt+1 })
 		if maxi == 0 {
 			if mini == 0 {
 				return append(Intervals{n}, in...)
 			}
 			return append(in[:mini], append(Intervals{n}, in[mini:]...)...)
 		}
+	}
 
 	if n.Mint < in[mini].Mint {
 		in[mini].Mint = n.Mint

tsdb/tombstones/tombstones_test.go

@@ -81,6 +81,22 @@ func TestDeletingTombstones(t *testing.T) {
 	require.Empty(t, intervals)
 }
 
+func TestTombstonesGetWithCopy(t *testing.T) {
+	stones := NewMemTombstones()
+	stones.AddInterval(1, Intervals{{Mint: 1, Maxt: 2}, {Mint: 7, Maxt: 8}, {Mint: 11, Maxt: 12}}...)
+
+	intervals0, err := stones.Get(1)
+	require.NoError(t, err)
+	require.Equal(t, Intervals{{Mint: 1, Maxt: 2}, {Mint: 7, Maxt: 8}, {Mint: 11, Maxt: 12}}, intervals0)
+	intervals1 := intervals0.Add(Interval{Mint: 4, Maxt: 6})
+	require.Equal(t, Intervals{{Mint: 1, Maxt: 2}, {Mint: 4, Maxt: 8}, {Mint: 11, Maxt: 12}}, intervals0) // Original slice changed.
+	require.Equal(t, Intervals{{Mint: 1, Maxt: 2}, {Mint: 4, Maxt: 8}, {Mint: 11, Maxt: 12}}, intervals1)
+
+	intervals2, err := stones.Get(1)
+	require.NoError(t, err)
+	require.Equal(t, Intervals{{Mint: 1, Maxt: 2}, {Mint: 7, Maxt: 8}, {Mint: 11, Maxt: 12}}, intervals2)
+}
+
 func TestTruncateBefore(t *testing.T) {
 	cases := []struct {
 		before  Intervals
@@ -210,6 +226,26 @@ func TestAddingNewIntervals(t *testing.T) {
 			new:   Interval{math.MinInt64, 10},
 			exp:   Intervals{{math.MinInt64, math.MaxInt64}},
 		},
+		{
+			exist: Intervals{{9, 10}},
+			new:   Interval{math.MinInt64, 7},
+			exp:   Intervals{{math.MinInt64, 7}, {9, 10}},
+		},
+		{
+			exist: Intervals{{9, 10}},
+			new:   Interval{12, math.MaxInt64},
+			exp:   Intervals{{9, 10}, {12, math.MaxInt64}},
+		},
+		{
+			exist: Intervals{{9, 10}},
+			new:   Interval{math.MinInt64, 8},
+			exp:   Intervals{{math.MinInt64, 10}},
+		},
+		{
+			exist: Intervals{{9, 10}},
+			new:   Interval{11, math.MaxInt64},
+			exp:   Intervals{{9, math.MaxInt64}},
+		},
 	}
 
 	for _, c := range cases {

tsdb/tsdbutil/chunks.go

@@ -71,9 +71,19 @@ func ChunkFromSamplesGeneric(s Samples) chunks.Meta {
 		case chunkenc.ValFloat:
 			ca.Append(s.Get(i).T(), s.Get(i).F())
 		case chunkenc.ValHistogram:
-			ca.AppendHistogram(s.Get(i).T(), s.Get(i).H())
+			h := s.Get(i).H()
+			ca.AppendHistogram(s.Get(i).T(), h)
+			if i == 0 && h.CounterResetHint == histogram.GaugeType {
+				hc := c.(*chunkenc.HistogramChunk)
+				hc.SetCounterResetHeader(chunkenc.GaugeType)
+			}
 		case chunkenc.ValFloatHistogram:
-			ca.AppendFloatHistogram(s.Get(i).T(), s.Get(i).FH())
+			fh := s.Get(i).FH()
+			ca.AppendFloatHistogram(s.Get(i).T(), fh)
+			if i == 0 && fh.CounterResetHint == histogram.GaugeType {
+				hc := c.(*chunkenc.FloatHistogramChunk)
+				hc.SetCounterResetHeader(chunkenc.GaugeType)
+			}
 		default:
 			panic(fmt.Sprintf("unknown sample type %s", sampleType.String()))
 		}

tsdb/tsdbutil/histogram.go

@@ -108,3 +108,13 @@ func GenerateTestGaugeFloatHistogram(i int) *histogram.FloatHistogram {
 	h.CounterResetHint = histogram.GaugeType
 	return h
 }
+
+func SetHistogramNotCounterReset(h *histogram.Histogram) *histogram.Histogram {
+	h.CounterResetHint = histogram.NotCounterReset
+	return h
+}
+
+func SetFloatHistogramNotCounterReset(h *histogram.FloatHistogram) *histogram.FloatHistogram {
+	h.CounterResetHint = histogram.NotCounterReset
+	return h
+}

tsdb/wlog/watcher.go

@@ -18,7 +18,7 @@ import (
 	"io"
 	"math"
 	"os"
-	"path"
+	"path/filepath"
 	"strconv"
 	"strings"
 	"time"
@@ -34,12 +34,16 @@ import (
 )
 
 const (
-	readPeriod         = 10 * time.Millisecond
 	checkpointPeriod   = 5 * time.Second
 	segmentCheckPeriod = 100 * time.Millisecond
 	consumer           = "consumer"
 )
 
+var (
+	ErrIgnorable = errors.New("ignore me")
+	readTimeout  = 15 * time.Second
+)
+
 // WriteTo is an interface used by the Watcher to send the samples it's read
 // from the WAL on to somewhere else. Functions will be called concurrently
 // and it is left to the implementer to make sure they are safe.
@@ -61,11 +65,17 @@ type WriteTo interface {
 	SeriesReset(int)
 }
 
+// Used to notifier the watcher that data has been written so that it can read.
+type WriteNotified interface {
+	Notify()
+}
+
 type WatcherMetrics struct {
 	recordsRead           *prometheus.CounterVec
 	recordDecodeFails     *prometheus.CounterVec
 	samplesSentPreTailing *prometheus.CounterVec
 	currentSegment        *prometheus.GaugeVec
+	notificationsSkipped  *prometheus.CounterVec
 }
 
 // Watcher watches the TSDB WAL for a given WriteTo.
@@ -88,7 +98,9 @@ type Watcher struct {
 	recordDecodeFailsMetric prometheus.Counter
 	samplesSentPreTailing   prometheus.Counter
 	currentSegmentMetric    prometheus.Gauge
+	notificationsSkipped    prometheus.Counter
 
+	readNotify chan struct{}
 	quit       chan struct{}
 	done       chan struct{}
 
@@ -134,6 +146,15 @@ func NewWatcherMetrics(reg prometheus.Registerer) *WatcherMetrics {
 			},
 			[]string{consumer},
 		),
+		notificationsSkipped: prometheus.NewCounterVec(
+			prometheus.CounterOpts{
+				Namespace: "prometheus",
+				Subsystem: "wal_watcher",
+				Name:      "notifications_skipped_total",
+				Help:      "The number of WAL write notifications that the Watcher has skipped due to already being in a WAL read routine.",
+			},
+			[]string{consumer},
+		),
 	}
 
 	if reg != nil {
@@ -141,6 +162,7 @@ func NewWatcherMetrics(reg prometheus.Registerer) *WatcherMetrics {
 		reg.MustRegister(m.recordDecodeFails)
 		reg.MustRegister(m.samplesSentPreTailing)
 		reg.MustRegister(m.currentSegment)
+		reg.MustRegister(m.notificationsSkipped)
 	}
 
 	return m
@@ -156,11 +178,12 @@ func NewWatcher(metrics *WatcherMetrics, readerMetrics *LiveReaderMetrics, logge
 		writer:         writer,
 		metrics:        metrics,
 		readerMetrics:  readerMetrics,
-		walDir:         path.Join(dir, "wal"),
+		walDir:         filepath.Join(dir, "wal"),
 		name:           name,
 		sendExemplars:  sendExemplars,
 		sendHistograms: sendHistograms,
 
+		readNotify: make(chan struct{}),
 		quit:       make(chan struct{}),
 		done:       make(chan struct{}),
 
@@ -168,6 +191,17 @@ func NewWatcher(metrics *WatcherMetrics, readerMetrics *LiveReaderMetrics, logge
 	}
 }
 
+func (w *Watcher) Notify() {
+	select {
+	case w.readNotify <- struct{}{}:
+		return
+	default: // default so we can exit
+		// we don't need a buffered channel or any buffering since
+		// for each notification it recv's the watcher will read until EOF
+		w.notificationsSkipped.Inc()
+	}
+}
+
 func (w *Watcher) setMetrics() {
 	// Setup the WAL Watchers metrics. We do this here rather than in the
 	// constructor because of the ordering of creating Queue Managers's,
@@ -177,6 +211,8 @@ func (w *Watcher) setMetrics() {
 		w.recordDecodeFailsMetric = w.metrics.recordDecodeFails.WithLabelValues(w.name)
 		w.samplesSentPreTailing = w.metrics.samplesSentPreTailing.WithLabelValues(w.name)
 		w.currentSegmentMetric = w.metrics.currentSegment.WithLabelValues(w.name)
+		w.notificationsSkipped = w.metrics.notificationsSkipped.WithLabelValues(w.name)
+
 	}
 }
 
@@ -262,7 +298,7 @@ func (w *Watcher) Run() error {
 
 		// On start, after reading the existing WAL for series records, we have a pointer to what is the latest segment.
 		// On subsequent calls to this function, currentSegment will have been incremented and we should open that segment.
-		if err := w.watch(currentSegment, currentSegment >= lastSegment); err != nil {
+		if err := w.watch(currentSegment, currentSegment >= lastSegment); err != nil && !errors.Is(err, ErrIgnorable) {
 			return err
 		}
 
@@ -330,6 +366,26 @@ func (w *Watcher) segments(dir string) ([]int, error) {
 	return refs, nil
 }
 
+func (w *Watcher) readAndHandleError(r *LiveReader, segmentNum int, tail bool, size int64) error {
+	err := w.readSegment(r, segmentNum, tail)
+
+	// Ignore all errors reading to end of segment whilst replaying the WAL.
+	if !tail {
+		if err != nil && errors.Cause(err) != io.EOF {
+			level.Warn(w.logger).Log("msg", "Ignoring error reading to end of segment, may have dropped data", "segment", segmentNum, "err", err)
+		} else if r.Offset() != size {
+			level.Warn(w.logger).Log("msg", "Expected to have read whole segment, may have dropped data", "segment", segmentNum, "read", r.Offset(), "size", size)
+		}
+		return ErrIgnorable
+	}
+
+	// Otherwise, when we are tailing, non-EOFs are fatal.
+	if errors.Cause(err) != io.EOF {
+		return err
+	}
+	return nil
+}
+
 // Use tail true to indicate that the reader is currently on a segment that is
 // actively being written to. If false, assume it's a full segment and we're
 // replaying it on start to cache the series records.
@@ -342,7 +398,7 @@ func (w *Watcher) watch(segmentNum int, tail bool) error {
 
 	reader := NewLiveReader(w.logger, w.readerMetrics, segment)
 
-	readTicker := time.NewTicker(readPeriod)
+	readTicker := time.NewTicker(readTimeout)
 	defer readTicker.Stop()
 
 	checkpointTicker := time.NewTicker(checkpointPeriod)
@@ -400,7 +456,6 @@ func (w *Watcher) watch(segmentNum int, tail bool) error {
 			if last <= segmentNum {
 				continue
 			}
-
 			err = w.readSegment(reader, segmentNum, tail)
 
 			// Ignore errors reading to end of segment whilst replaying the WAL.
@@ -421,24 +476,23 @@ func (w *Watcher) watch(segmentNum int, tail bool) error {
 
 			return nil
 
+		// we haven't read due to a notification in quite some time, try reading anyways
 		case <-readTicker.C:
-			err = w.readSegment(reader, segmentNum, tail)
+			level.Debug(w.logger).Log("msg", "Watcher is reading the WAL due to timeout, haven't received any write notifications recently", "timeout", readTimeout)
-
+			err := w.readAndHandleError(reader, segmentNum, tail, size)
-			// Ignore all errors reading to end of segment whilst replaying the WAL.
+			if err != nil {
-			if !tail {
-				switch {
-				case err != nil && errors.Cause(err) != io.EOF:
-					level.Warn(w.logger).Log("msg", "Ignoring error reading to end of segment, may have dropped data", "segment", segmentNum, "err", err)
-				case reader.Offset() != size:
-					level.Warn(w.logger).Log("msg", "Expected to have read whole segment, may have dropped data", "segment", segmentNum, "read", reader.Offset(), "size", size)
-				}
-				return nil
-			}
-
-			// Otherwise, when we are tailing, non-EOFs are fatal.
-			if errors.Cause(err) != io.EOF {
 				return err
 			}
+			// still want to reset the ticker so we don't read too often
+			readTicker.Reset(readTimeout)
+
+		case <-w.readNotify:
+			err := w.readAndHandleError(reader, segmentNum, tail, size)
+			if err != nil {
+				return err
+			}
+			// still want to reset the ticker so we don't read too often
+			readTicker.Reset(readTimeout)
 		}
 	}
 }
@@ -691,7 +745,7 @@ func (w *Watcher) readCheckpoint(checkpointDir string, readFn segmentReadFn) err
 func checkpointNum(dir string) (int, error) {
 	// Checkpoint dir names are in the format checkpoint.000001
 	// dir may contain a hidden directory, so only check the base directory
-	chunks := strings.Split(path.Base(dir), ".")
+	chunks := strings.Split(filepath.Base(dir), ".")
 	if len(chunks) != 2 {
 		return 0, errors.Errorf("invalid checkpoint dir string: %s", dir)
 	}

tsdb/wlog/watcher_test.go

@@ -104,7 +104,7 @@ func (wtm *writeToMock) SeriesReset(index int) {
 	}
 }
 
-func (wtm *writeToMock) checkNumLabels() int {
+func (wtm *writeToMock) checkNumSeries() int {
 	wtm.seriesLock.Lock()
 	defer wtm.seriesLock.Unlock()
 	return len(wtm.seriesSegmentIndexes)
@@ -230,9 +230,9 @@ func TestTailSamples(t *testing.T) {
 			expectedExemplars := seriesCount * exemplarsCount
 			expectedHistograms := seriesCount * histogramsCount
 			retry(t, defaultRetryInterval, defaultRetries, func() bool {
-				return wt.checkNumLabels() >= expectedSeries
+				return wt.checkNumSeries() >= expectedSeries
 			})
-			require.Equal(t, expectedSeries, wt.checkNumLabels(), "did not receive the expected number of series")
+			require.Equal(t, expectedSeries, wt.checkNumSeries(), "did not receive the expected number of series")
 			require.Equal(t, expectedSamples, wt.samplesAppended, "did not receive the expected number of samples")
 			require.Equal(t, expectedExemplars, wt.exemplarsAppended, "did not receive the expected number of exemplars")
 			require.Equal(t, expectedHistograms, wt.histogramsAppended, "did not receive the expected number of histograms")
@@ -290,7 +290,7 @@ func TestReadToEndNoCheckpoint(t *testing.T) {
 				}
 			}
 			require.NoError(t, w.Log(recs...))
-
+			readTimeout = time.Second
 			_, _, err = Segments(w.Dir())
 			require.NoError(t, err)
 
@@ -299,11 +299,10 @@ func TestReadToEndNoCheckpoint(t *testing.T) {
 			go watcher.Start()
 
 			expected := seriesCount
-			retry(t, defaultRetryInterval, defaultRetries, func() bool {
+			require.Eventually(t, func() bool {
-				return wt.checkNumLabels() >= expected
+				return wt.checkNumSeries() == expected
-			})
+			}, 20*time.Second, 1*time.Second)
 			watcher.Stop()
-			require.Equal(t, expected, wt.checkNumLabels())
 		})
 	}
 }
@@ -383,16 +382,17 @@ func TestReadToEndWithCheckpoint(t *testing.T) {
 
 			_, _, err = Segments(w.Dir())
 			require.NoError(t, err)
+			readTimeout = time.Second
 			wt := newWriteToMock()
 			watcher := NewWatcher(wMetrics, nil, nil, "", wt, dir, false, false)
 			go watcher.Start()
 
 			expected := seriesCount * 2
-			retry(t, defaultRetryInterval, defaultRetries, func() bool {
+
-				return wt.checkNumLabels() >= expected
+			require.Eventually(t, func() bool {
-			})
+				return wt.checkNumSeries() == expected
+			}, 10*time.Second, 1*time.Second)
 			watcher.Stop()
-			require.Equal(t, expected, wt.checkNumLabels())
 		})
 	}
 }
@@ -460,10 +460,10 @@ func TestReadCheckpoint(t *testing.T) {
 
 			expectedSeries := seriesCount
 			retry(t, defaultRetryInterval, defaultRetries, func() bool {
-				return wt.checkNumLabels() >= expectedSeries
+				return wt.checkNumSeries() >= expectedSeries
 			})
 			watcher.Stop()
-			require.Equal(t, expectedSeries, wt.checkNumLabels())
+			require.Equal(t, expectedSeries, wt.checkNumSeries())
 		})
 	}
 }
@@ -595,6 +595,7 @@ func TestCheckpointSeriesReset(t *testing.T) {
 			_, _, err = Segments(w.Dir())
 			require.NoError(t, err)
 
+			readTimeout = time.Second
 			wt := newWriteToMock()
 			watcher := NewWatcher(wMetrics, nil, nil, "", wt, dir, false, false)
 			watcher.MaxSegment = -1
@@ -602,9 +603,11 @@ func TestCheckpointSeriesReset(t *testing.T) {
 
 			expected := seriesCount
 			retry(t, defaultRetryInterval, defaultRetries, func() bool {
-				return wt.checkNumLabels() >= expected
+				return wt.checkNumSeries() >= expected
 			})
-			require.Equal(t, seriesCount, wt.checkNumLabels())
+			require.Eventually(t, func() bool {
+				return wt.checkNumSeries() == seriesCount
+			}, 10*time.Second, 1*time.Second)
 
 			_, err = Checkpoint(log.NewNopLogger(), w, 2, 4, func(x chunks.HeadSeriesRef) bool { return true }, 0)
 			require.NoError(t, err)
@@ -621,7 +624,9 @@ func TestCheckpointSeriesReset(t *testing.T) {
 			// If you modify the checkpoint and truncate segment #'s run the test to see how
 			// many series records you end up with and change the last Equals check accordingly
 			// or modify the Equals to Assert(len(wt.seriesLabels) < seriesCount*10)
-			require.Equal(t, tc.segments, wt.checkNumLabels())
+			require.Eventually(t, func() bool {
+				return wt.checkNumSeries() == tc.segments
+			}, 20*time.Second, 1*time.Second)
 		})
 	}
 }

tsdb/wlog/wlog.go

@@ -188,6 +188,8 @@ type WL struct {
 	compress    bool
 	snappyBuf   []byte
 
+	WriteNotified WriteNotified
+
 	metrics *wlMetrics
 }
 
@@ -343,6 +345,10 @@ func (w *WL) Dir() string {
 	return w.dir
 }
 
+func (w *WL) SetWriteNotified(wn WriteNotified) {
+	w.WriteNotified = wn
+}
+
 func (w *WL) run() {
 Loop:
 	for {

web/api/v1/api.go

@@ -171,7 +171,7 @@ type TSDBAdminStats interface {
 	CleanTombstones() error
 	Delete(mint, maxt int64, ms ...*labels.Matcher) error
 	Snapshot(dir string, withHead bool) error
-	Stats(statsByLabelName string) (*tsdb.Stats, error)
+	Stats(statsByLabelName string, limit int) (*tsdb.Stats, error)
 	WALReplayStatus() (tsdb.WALReplayStatus, error)
 }
 
@@ -1480,8 +1480,15 @@ func TSDBStatsFromIndexStats(stats []index.Stat) []TSDBStat {
 	return result
 }
 
-func (api *API) serveTSDBStatus(*http.Request) apiFuncResult {
+func (api *API) serveTSDBStatus(r *http.Request) apiFuncResult {
-	s, err := api.db.Stats(labels.MetricName)
+	limit := 10
+	if s := r.FormValue("limit"); s != "" {
+		var err error
+		if limit, err = strconv.Atoi(s); err != nil || limit < 1 {
+			return apiFuncResult{nil, &apiError{errorBadData, errors.New("limit must be a positive number")}, nil, nil}
+		}
+	}
+	s, err := api.db.Stats(labels.MetricName, limit)
 	if err != nil {
 		return apiFuncResult{nil, &apiError{errorInternal, err}, nil, nil}
 	}

web/api/v1/api_test.go

@@ -2620,7 +2620,7 @@ type fakeDB struct {
 func (f *fakeDB) CleanTombstones() error                        { return f.err }
 func (f *fakeDB) Delete(int64, int64, ...*labels.Matcher) error { return f.err }
 func (f *fakeDB) Snapshot(string, bool) error                   { return f.err }
-func (f *fakeDB) Stats(statsByLabelName string) (_ *tsdb.Stats, retErr error) {
+func (f *fakeDB) Stats(statsByLabelName string, limit int) (_ *tsdb.Stats, retErr error) {
 	dbDir, err := os.MkdirTemp("", "tsdb-api-ready")
 	if err != nil {
 		return nil, err
@@ -2634,7 +2634,7 @@ func (f *fakeDB) Stats(statsByLabelName string) (_ *tsdb.Stats, retErr error) {
 	opts := tsdb.DefaultHeadOptions()
 	opts.ChunkRange = 1000
 	h, _ := tsdb.NewHead(nil, nil, nil, nil, opts, nil)
-	return h.Stats(statsByLabelName), nil
+	return h.Stats(statsByLabelName, limit), nil
 }
 
 func (f *fakeDB) WALReplayStatus() (tsdb.WALReplayStatus, error) {
@@ -3206,9 +3206,20 @@ func TestTSDBStatus(t *testing.T) {
 		{
 			db:       tsdb,
 			endpoint: tsdbStatusAPI,
-
 			errType:  errorNone,
 		},
+		{
+			db:       tsdb,
+			endpoint: tsdbStatusAPI,
+			values:   map[string][]string{"limit": {"20"}},
+			errType:  errorNone,
+		},
+		{
+			db:       tsdb,
+			endpoint: tsdbStatusAPI,
+			values:   map[string][]string{"limit": {"0"}},
+			errType:  errorBadData,
+		},
 	} {
 		tc := tc
 		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {

web/federate_test.go

@@ -251,7 +251,7 @@ func (notReadyReadStorage) StartTime() (int64, error) {
 	return 0, errors.Wrap(tsdb.ErrNotReady, "wrap")
 }
 
-func (notReadyReadStorage) Stats(string) (*tsdb.Stats, error) {
+func (notReadyReadStorage) Stats(string, int) (*tsdb.Stats, error) {
 	return nil, errors.Wrap(tsdb.ErrNotReady, "wrap")
 }
 
@@ -378,7 +378,7 @@ func TestFederationWithNativeHistograms(t *testing.T) {
 	body, err := io.ReadAll(res.Body)
 	require.NoError(t, err)
 
-	p := textparse.NewProtobufParser(body)
+	p := textparse.NewProtobufParser(body, false)
 	var actVec promql.Vector
 	metricFamilies := 0
 	l := labels.Labels{}

web/ui/module/codemirror-promql/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@prometheus-io/codemirror-promql",
-  "version": "0.43.0",
+  "version": "0.44.0",
   "description": "a CodeMirror mode for the PromQL language",
   "types": "dist/esm/index.d.ts",
   "module": "dist/esm/index.js",
@@ -29,7 +29,7 @@
   },
   "homepage": "https://github.com/prometheus/prometheus/blob/main/web/ui/module/codemirror-promql/README.md",
   "dependencies": {
-    "@prometheus-io/lezer-promql": "0.43.0",
+    "@prometheus-io/lezer-promql": "0.44.0",
     "lru-cache": "^6.0.0"
   },
   "devDependencies": {

web/ui/module/lezer-promql/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@prometheus-io/lezer-promql",
-  "version": "0.43.0",
+  "version": "0.44.0",
   "description": "lezer-based PromQL grammar",
   "main": "dist/index.cjs",
   "type": "module",

web/ui/package-lock.json

@@ -28,10 +28,10 @@
     },
     "module/codemirror-promql": {
       "name": "@prometheus-io/codemirror-promql",
-      "version": "0.43.0",
+      "version": "0.44.0",
       "license": "Apache-2.0",
       "dependencies": {
-        "@prometheus-io/lezer-promql": "0.43.0",
+        "@prometheus-io/lezer-promql": "0.44.0",
         "lru-cache": "^6.0.0"
       },
       "devDependencies": {
@@ -61,7 +61,7 @@
     },
     "module/lezer-promql": {
       "name": "@prometheus-io/lezer-promql",
-      "version": "0.43.0",
+      "version": "0.44.0",
       "license": "Apache-2.0",
       "devDependencies": {
         "@lezer/generator": "^1.2.2",
@@ -20763,7 +20763,7 @@
     },
     "react-app": {
       "name": "@prometheus-io/app",
-      "version": "0.43.0",
+      "version": "0.44.0",
       "dependencies": {
         "@codemirror/autocomplete": "^6.4.0",
         "@codemirror/commands": "^6.2.0",
@@ -20781,7 +20781,7 @@
         "@lezer/lr": "^1.3.1",
         "@nexucis/fuzzy": "^0.4.1",
         "@nexucis/kvsearch": "^0.8.1",
-        "@prometheus-io/codemirror-promql": "0.43.0",
+        "@prometheus-io/codemirror-promql": "0.44.0",
         "bootstrap": "^4.6.2",
         "css.escape": "^1.5.1",
         "downshift": "^7.2.0",
@@ -23417,7 +23417,7 @@
         "@lezer/lr": "^1.3.1",
         "@nexucis/fuzzy": "^0.4.1",
         "@nexucis/kvsearch": "^0.8.1",
-        "@prometheus-io/codemirror-promql": "0.43.0",
+        "@prometheus-io/codemirror-promql": "0.44.0",
         "@testing-library/react-hooks": "^7.0.2",
         "@types/enzyme": "^3.10.12",
         "@types/flot": "0.0.32",
@@ -23468,7 +23468,7 @@
         "@lezer/common": "^1.0.2",
         "@lezer/highlight": "^1.1.3",
         "@lezer/lr": "^1.3.1",
-        "@prometheus-io/lezer-promql": "0.43.0",
+        "@prometheus-io/lezer-promql": "0.44.0",
         "@types/lru-cache": "^5.1.1",
         "isomorphic-fetch": "^3.0.0",
         "lru-cache": "^6.0.0",

web/ui/react-app/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@prometheus-io/app",
-  "version": "0.43.0",
+  "version": "0.44.0",
   "private": true,
   "dependencies": {
     "@codemirror/autocomplete": "^6.4.0",
@@ -19,7 +19,7 @@
     "@lezer/common": "^1.0.2",
     "@nexucis/fuzzy": "^0.4.1",
     "@nexucis/kvsearch": "^0.8.1",
-    "@prometheus-io/codemirror-promql": "0.43.0",
+    "@prometheus-io/codemirror-promql": "0.44.0",
     "bootstrap": "^4.6.2",
     "css.escape": "^1.5.1",
     "downshift": "^7.2.0",

web/web_test.go

@@ -52,8 +52,8 @@ type dbAdapter struct {
 	*tsdb.DB
 }
 
-func (a *dbAdapter) Stats(statsByLabelName string) (*tsdb.Stats, error) {
+func (a *dbAdapter) Stats(statsByLabelName string, limit int) (*tsdb.Stats, error) {
-	return a.Head().Stats(statsByLabelName), nil
+	return a.Head().Stats(statsByLabelName, limit), nil
 }
 
 func (a *dbAdapter) WALReplayStatus() (tsdb.WALReplayStatus, error) {