Merge pull request #14354 from bboreham/ooo-head-together

[PERF] TSDB: Query head and ooo-head together

The current implementation of out-of-order querying runs two queriers which each iterate all series in the head, then runs a merge operation on the output.

This PR adds HeadAndOOOQuerier which iterates just once over series, then where necessary merges chunks from in-order and out-of-order lists.

In order to distinguish in-order from out-of-order chunk references I set bit 23 (i.e. 1<<23) on ooo references; this reduces the maximum number of chunks from 16 million to 8 million.

Note one side-effect of this change is that results may come in a different order - the merge operation done previously required a sort of all series. This only changes where Prometheus does not guarantee the order.

Fixes #11628

cmd/promtool/tsdb_test.go

@@ -20,6 +20,7 @@ import (
 	"math"
 	"os"
 	"runtime"
+	"slices"
 	"strings"
 	"testing"
 	"time"
@@ -152,12 +153,18 @@ func TestTSDBDump(t *testing.T) {
 			expectedMetrics, err := os.ReadFile(tt.expectedDump)
 			require.NoError(t, err)
 			expectedMetrics = normalizeNewLine(expectedMetrics)
-			// even though in case of one matcher samples are not sorted, the order in the cases above should stay the same.
-			require.Equal(t, string(expectedMetrics), dumpedMetrics)
+			// Sort both, because Prometheus does not guarantee the output order.
+			require.Equal(t, sortLines(string(expectedMetrics)), sortLines(dumpedMetrics))
 		})
 	}
 }
 
+func sortLines(buf string) string {
+	lines := strings.Split(buf, "\n")
+	slices.Sort(lines)
+	return strings.Join(lines, "\n")
+}
+
 func TestTSDBDumpOpenMetrics(t *testing.T) {
 	storage := promqltest.LoadedStorage(t, `
 		load 1m
@@ -169,7 +176,7 @@ func TestTSDBDumpOpenMetrics(t *testing.T) {
 	require.NoError(t, err)
 	expectedMetrics = normalizeNewLine(expectedMetrics)
 	dumpedMetrics := getDumpedSamples(t, storage.Dir(), math.MinInt64, math.MaxInt64, []string{"{__name__=~'(?s:.*)'}"}, formatSeriesSetOpenMetrics)
-	require.Equal(t, string(expectedMetrics), dumpedMetrics)
+	require.Equal(t, sortLines(string(expectedMetrics)), sortLines(dumpedMetrics))
 }
 
 func TestTSDBDumpOpenMetricsRoundTrip(t *testing.T) {

tsdb/db.go

@@ -2029,7 +2029,7 @@ func (db *DB) Querier(mint, maxt int64) (_ storage.Querier, err error) {
 		}
 	}
 
-	blockQueriers := make([]storage.Querier, 0, len(blocks)+2) // +2 to allow for possible in-order and OOO head queriers
+	blockQueriers := make([]storage.Querier, 0, len(blocks)+1) // +1 to allow for possible head querier.
 
 	defer func() {
 		if err != nil {
@@ -2041,10 +2041,12 @@ func (db *DB) Querier(mint, maxt int64) (_ storage.Querier, err error) {
 		}
 	}()
 
-	if maxt >= db.head.MinTime() {
+	overlapsOOO := overlapsClosedInterval(mint, maxt, db.head.MinOOOTime(), db.head.MaxOOOTime())
+	var headQuerier storage.Querier
+	if maxt >= db.head.MinTime() || overlapsOOO {
 		rh := NewRangeHead(db.head, mint, maxt)
 		var err error
-		inOrderHeadQuerier, err := db.blockQuerierFunc(rh, mint, maxt)
+		headQuerier, err = db.blockQuerierFunc(rh, mint, maxt)
 		if err != nil {
 			return nil, fmt.Errorf("open block querier for head %s: %w", rh, err)
 		}
@@ -2054,36 +2056,28 @@ func (db *DB) Querier(mint, maxt int64) (_ storage.Querier, err error) {
 		// won't run into a race later since any truncation that comes after will wait on this querier if it overlaps.
 		shouldClose, getNew, newMint := db.head.IsQuerierCollidingWithTruncation(mint, maxt)
 		if shouldClose {
-			if err := inOrderHeadQuerier.Close(); err != nil {
+			if err := headQuerier.Close(); err != nil {
 				return nil, fmt.Errorf("closing head block querier %s: %w", rh, err)
 			}
-			inOrderHeadQuerier = nil
+			headQuerier = nil
 		}
 		if getNew {
 			rh := NewRangeHead(db.head, newMint, maxt)
-			inOrderHeadQuerier, err = db.blockQuerierFunc(rh, newMint, maxt)
+			headQuerier, err = db.blockQuerierFunc(rh, newMint, maxt)
 			if err != nil {
 				return nil, fmt.Errorf("open block querier for head while getting new querier %s: %w", rh, err)
 			}
 		}
-
-		if inOrderHeadQuerier != nil {
-			blockQueriers = append(blockQueriers, inOrderHeadQuerier)
-		}
 	}
 
-	if overlapsClosedInterval(mint, maxt, db.head.MinOOOTime(), db.head.MaxOOOTime()) {
-		rh := NewOOORangeHead(db.head, mint, maxt, db.lastGarbageCollectedMmapRef)
-		var err error
-		outOfOrderHeadQuerier, err := db.blockQuerierFunc(rh, mint, maxt)
-		if err != nil {
-			// If BlockQuerierFunc() failed, make sure to clean up the pending read created by NewOOORangeHead.
-			rh.isoState.Close()
+	if overlapsOOO {
+		// We need to fetch from in-order and out-of-order chunks: wrap the headQuerier.
+		isoState := db.head.oooIso.TrackReadAfter(db.lastGarbageCollectedMmapRef)
+		headQuerier = NewHeadAndOOOQuerier(mint, maxt, db.head, isoState, headQuerier)
+	}
 
-			return nil, fmt.Errorf("open block querier for ooo head %s: %w", rh, err)
-		}
-
-		blockQueriers = append(blockQueriers, outOfOrderHeadQuerier)
+	if headQuerier != nil {
+		blockQueriers = append(blockQueriers, headQuerier)
 	}
 
 	for _, b := range blocks {
@@ -2111,7 +2105,7 @@ func (db *DB) blockChunkQuerierForRange(mint, maxt int64) (_ []storage.ChunkQuer
 		}
 	}
 
-	blockQueriers := make([]storage.ChunkQuerier, 0, len(blocks)+2) // +2 to allow for possible in-order and OOO head queriers
+	blockQueriers := make([]storage.ChunkQuerier, 0, len(blocks)+1) // +1 to allow for possible head querier.
 
 	defer func() {
 		if err != nil {
@@ -2123,9 +2117,11 @@ func (db *DB) blockChunkQuerierForRange(mint, maxt int64) (_ []storage.ChunkQuer
 		}
 	}()
 
-	if maxt >= db.head.MinTime() {
+	overlapsOOO := overlapsClosedInterval(mint, maxt, db.head.MinOOOTime(), db.head.MaxOOOTime())
+	var headQuerier storage.ChunkQuerier
+	if maxt >= db.head.MinTime() || overlapsOOO {
 		rh := NewRangeHead(db.head, mint, maxt)
-		inOrderHeadQuerier, err := db.blockChunkQuerierFunc(rh, mint, maxt)
+		headQuerier, err = db.blockChunkQuerierFunc(rh, mint, maxt)
 		if err != nil {
 			return nil, fmt.Errorf("open querier for head %s: %w", rh, err)
 		}
@@ -2135,35 +2131,28 @@ func (db *DB) blockChunkQuerierForRange(mint, maxt int64) (_ []storage.ChunkQuer
 		// won't run into a race later since any truncation that comes after will wait on this querier if it overlaps.
 		shouldClose, getNew, newMint := db.head.IsQuerierCollidingWithTruncation(mint, maxt)
 		if shouldClose {
-			if err := inOrderHeadQuerier.Close(); err != nil {
+			if err := headQuerier.Close(); err != nil {
 				return nil, fmt.Errorf("closing head querier %s: %w", rh, err)
 			}
-			inOrderHeadQuerier = nil
+			headQuerier = nil
 		}
 		if getNew {
 			rh := NewRangeHead(db.head, newMint, maxt)
-			inOrderHeadQuerier, err = db.blockChunkQuerierFunc(rh, newMint, maxt)
+			headQuerier, err = db.blockChunkQuerierFunc(rh, newMint, maxt)
 			if err != nil {
 				return nil, fmt.Errorf("open querier for head while getting new querier %s: %w", rh, err)
 			}
 		}
-
-		if inOrderHeadQuerier != nil {
-			blockQueriers = append(blockQueriers, inOrderHeadQuerier)
-		}
 	}
 
-	if overlapsClosedInterval(mint, maxt, db.head.MinOOOTime(), db.head.MaxOOOTime()) {
-		rh := NewOOORangeHead(db.head, mint, maxt, db.lastGarbageCollectedMmapRef)
-		outOfOrderHeadQuerier, err := db.blockChunkQuerierFunc(rh, mint, maxt)
-		if err != nil {
-			// If NewBlockQuerier() failed, make sure to clean up the pending read created by NewOOORangeHead.
-			rh.isoState.Close()
+	if overlapsOOO {
+		// We need to fetch from in-order and out-of-order chunks: wrap the headQuerier.
+		isoState := db.head.oooIso.TrackReadAfter(db.lastGarbageCollectedMmapRef)
+		headQuerier = NewHeadAndOOOChunkQuerier(mint, maxt, db.head, isoState, headQuerier)
+	}
 
-			return nil, fmt.Errorf("open block chunk querier for ooo head %s: %w", rh, err)
-		}
-
-		blockQueriers = append(blockQueriers, outOfOrderHeadQuerier)
+	if headQuerier != nil {
+		blockQueriers = append(blockQueriers, headQuerier)
 	}
 
 	for _, b := range blocks {

tsdb/head_append.go

@@ -19,6 +19,7 @@ import (
 	"fmt"
 	"math"
 
+	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
 
 	"github.com/prometheus/prometheus/model/exemplar"
@@ -936,7 +937,7 @@ func (a *headAppender) Commit() (err error) {
 			// Sample is OOO and OOO handling is enabled
 			// and the delta is within the OOO tolerance.
 			var mmapRefs []chunks.ChunkDiskMapperRef
-			ok, chunkCreated, mmapRefs = series.insert(s.T, s.V, nil, nil, a.head.chunkDiskMapper, oooCapMax)
+			ok, chunkCreated, mmapRefs = series.insert(s.T, s.V, nil, nil, a.head.chunkDiskMapper, oooCapMax, a.head.logger)
 			if chunkCreated {
 				r, ok := oooMmapMarkers[series.ref]
 				if !ok || r != nil {
@@ -1083,14 +1084,14 @@ func (a *headAppender) Commit() (err error) {
 }
 
 // insert is like append, except it inserts. Used for OOO samples.
-func (s *memSeries) insert(t int64, v float64, h *histogram.Histogram, fh *histogram.FloatHistogram, chunkDiskMapper *chunks.ChunkDiskMapper, oooCapMax int64) (inserted, chunkCreated bool, mmapRefs []chunks.ChunkDiskMapperRef) {
+func (s *memSeries) insert(t int64, v float64, h *histogram.Histogram, fh *histogram.FloatHistogram, chunkDiskMapper *chunks.ChunkDiskMapper, oooCapMax int64, logger log.Logger) (inserted, chunkCreated bool, mmapRefs []chunks.ChunkDiskMapperRef) {
 	if s.ooo == nil {
 		s.ooo = &memSeriesOOOFields{}
 	}
 	c := s.ooo.oooHeadChunk
 	if c == nil || c.chunk.NumSamples() == int(oooCapMax) {
 		// Note: If no new samples come in then we rely on compaction to clean up stale in-memory OOO chunks.
-		c, mmapRefs = s.cutNewOOOHeadChunk(t, chunkDiskMapper)
+		c, mmapRefs = s.cutNewOOOHeadChunk(t, chunkDiskMapper, logger)
 		chunkCreated = true
 	}
 
@@ -1444,9 +1445,9 @@ func (s *memSeries) cutNewHeadChunk(mint int64, e chunkenc.Encoding, chunkRange
 }
 
 // cutNewOOOHeadChunk cuts a new OOO chunk and m-maps the old chunk.
-// The caller must ensure that s.ooo is not nil.
-func (s *memSeries) cutNewOOOHeadChunk(mint int64, chunkDiskMapper *chunks.ChunkDiskMapper) (*oooHeadChunk, []chunks.ChunkDiskMapperRef) {
-	ref := s.mmapCurrentOOOHeadChunk(chunkDiskMapper)
+// The caller must ensure that s is locked and s.ooo is not nil.
+func (s *memSeries) cutNewOOOHeadChunk(mint int64, chunkDiskMapper *chunks.ChunkDiskMapper, logger log.Logger) (*oooHeadChunk, []chunks.ChunkDiskMapperRef) {
+	ref := s.mmapCurrentOOOHeadChunk(chunkDiskMapper, logger)
 
 	s.ooo.oooHeadChunk = &oooHeadChunk{
 		chunk:   NewOOOChunk(),
@@ -1457,7 +1458,8 @@ func (s *memSeries) cutNewOOOHeadChunk(mint int64, chunkDiskMapper *chunks.Chunk
 	return s.ooo.oooHeadChunk, ref
 }
 
-func (s *memSeries) mmapCurrentOOOHeadChunk(chunkDiskMapper *chunks.ChunkDiskMapper) []chunks.ChunkDiskMapperRef {
+// s must be locked when calling.
+func (s *memSeries) mmapCurrentOOOHeadChunk(chunkDiskMapper *chunks.ChunkDiskMapper, logger log.Logger) []chunks.ChunkDiskMapperRef {
 	if s.ooo == nil || s.ooo.oooHeadChunk == nil {
 		// OOO is not enabled or there is no head chunk, so nothing to m-map here.
 		return nil
@@ -1469,6 +1471,10 @@ func (s *memSeries) mmapCurrentOOOHeadChunk(chunkDiskMapper *chunks.ChunkDiskMap
 	}
 	chunkRefs := make([]chunks.ChunkDiskMapperRef, 0, 1)
 	for _, memchunk := range chks {
+		if len(s.ooo.oooMmappedChunks) >= (oooChunkIDMask - 1) {
+			level.Error(logger).Log("msg", "Too many OOO chunks, dropping data", "series", s.lset.String())
+			break
+		}
 		chunkRef := chunkDiskMapper.WriteChunk(s.ref, s.ooo.oooHeadChunk.minTime, s.ooo.oooHeadChunk.maxTime, memchunk.chunk, true, handleChunkWriteError)
 		chunkRefs = append(chunkRefs, chunkRef)
 		s.ooo.oooMmappedChunks = append(s.ooo.oooMmappedChunks, &mmappedChunk{

tsdb/head_read.go

@@ -199,13 +199,18 @@ func (h *headIndexReader) Series(ref storage.SeriesRef, builder *labels.ScratchB
 	defer s.Unlock()
 
 	*chks = (*chks)[:0]
+	*chks = appendSeriesChunks(s, h.mint, h.maxt, *chks)
 
+	return nil
+}
+
+func appendSeriesChunks(s *memSeries, mint, maxt int64, chks []chunks.Meta) []chunks.Meta {
 	for i, c := range s.mmappedChunks {
 		// Do not expose chunks that are outside of the specified range.
-		if !c.OverlapsClosedInterval(h.mint, h.maxt) {
+		if !c.OverlapsClosedInterval(mint, maxt) {
 			continue
 		}
-		*chks = append(*chks, chunks.Meta{
+		chks = append(chks, chunks.Meta{
 			MinTime: c.minTime,
 			MaxTime: c.maxTime,
 			Ref:     chunks.ChunkRef(chunks.NewHeadChunkRef(s.ref, s.headChunkID(i))),
@@ -223,8 +228,8 @@ func (h *headIndexReader) Series(ref storage.SeriesRef, builder *labels.ScratchB
 			} else {
 				maxTime = chk.maxTime
 			}
-			if chk.OverlapsClosedInterval(h.mint, h.maxt) {
-				*chks = append(*chks, chunks.Meta{
+			if chk.OverlapsClosedInterval(mint, maxt) {
+				chks = append(chks, chunks.Meta{
 					MinTime: chk.minTime,
 					MaxTime: maxTime,
 					Ref:     chunks.ChunkRef(chunks.NewHeadChunkRef(s.ref, s.headChunkID(len(s.mmappedChunks)+j))),
@@ -233,8 +238,7 @@ func (h *headIndexReader) Series(ref storage.SeriesRef, builder *labels.ScratchB
 			j++
 		}
 	}
-
-	return nil
+	return chks
 }
 
 // headChunkID returns the HeadChunkID referred to by the given position.
@@ -244,12 +248,20 @@ func (s *memSeries) headChunkID(pos int) chunks.HeadChunkID {
 	return chunks.HeadChunkID(pos) + s.firstChunkID
 }
 
+const oooChunkIDMask = 1 << 23
+
 // oooHeadChunkID returns the HeadChunkID referred to by the given position.
+// Only the bottom 24 bits are used. Bit 23 is always 1 for an OOO chunk; for the rest:
 // * 0 <= pos < len(s.oooMmappedChunks) refer to s.oooMmappedChunks[pos]
 // * pos == len(s.oooMmappedChunks) refers to s.oooHeadChunk
 // The caller must ensure that s.ooo is not nil.
 func (s *memSeries) oooHeadChunkID(pos int) chunks.HeadChunkID {
-	return chunks.HeadChunkID(pos) + s.ooo.firstOOOChunkID
+	return (chunks.HeadChunkID(pos) + s.ooo.firstOOOChunkID) | oooChunkIDMask
+}
+
+func unpackHeadChunkRef(ref chunks.ChunkRef) (seriesID chunks.HeadSeriesRef, chunkID chunks.HeadChunkID, isOOO bool) {
+	sid, cid := chunks.HeadChunkRef(ref).Unpack()
+	return sid, (cid & (oooChunkIDMask - 1)), (cid & oooChunkIDMask) != 0
 }
 
 // LabelValueFor returns label value for the given label name in the series referred to by ID.
@@ -339,10 +351,15 @@ func (h *headChunkReader) ChunkOrIterable(meta chunks.Meta) (chunkenc.Chunk, chu
 	return chk, nil, err
 }
 
-// ChunkWithCopy returns the chunk for the reference number.
-// If the chunk is the in-memory chunk, then it makes a copy and returns the copied chunk.
-func (h *headChunkReader) ChunkWithCopy(meta chunks.Meta) (chunkenc.Chunk, int64, error) {
-	return h.chunk(meta, true)
+type ChunkReaderWithCopy interface {
+	ChunkOrIterableWithCopy(meta chunks.Meta) (chunkenc.Chunk, chunkenc.Iterable, int64, error)
+}
+
+// ChunkOrIterableWithCopy returns the chunk for the reference number.
+// If the chunk is the in-memory chunk, then it makes a copy and returns the copied chunk, plus the max time of the chunk.
+func (h *headChunkReader) ChunkOrIterableWithCopy(meta chunks.Meta) (chunkenc.Chunk, chunkenc.Iterable, int64, error) {
+	chk, maxTime, err := h.chunk(meta, true)
+	return chk, nil, maxTime, err
 }
 
 // chunk returns the chunk for the reference number.
@@ -358,9 +375,14 @@ func (h *headChunkReader) chunk(meta chunks.Meta, copyLastChunk bool) (chunkenc.
 	}
 
 	s.Lock()
+	defer s.Unlock()
+	return h.chunkFromSeries(s, cid, copyLastChunk)
+}
+
+// Call with s locked.
+func (h *headChunkReader) chunkFromSeries(s *memSeries, cid chunks.HeadChunkID, copyLastChunk bool) (chunkenc.Chunk, int64, error) {
 	c, headChunk, isOpen, err := s.chunk(cid, h.head.chunkDiskMapper, &h.head.memChunkPool)
 	if err != nil {
-		s.Unlock()
 		return nil, 0, err
 	}
 	defer func() {
@@ -374,7 +396,6 @@ func (h *headChunkReader) chunk(meta chunks.Meta, copyLastChunk bool) (chunkenc.
 
 	// This means that the chunk is outside the specified range.
 	if !c.OverlapsClosedInterval(h.mint, h.maxt) {
-		s.Unlock()
 		return nil, 0, storage.ErrNotFound
 	}
 
@@ -391,7 +412,6 @@ func (h *headChunkReader) chunk(meta chunks.Meta, copyLastChunk bool) (chunkenc.
 			return nil, 0, err
 		}
 	}
-	s.Unlock()
 
 	return &safeHeadChunk{
 		Chunk:    chk,
@@ -461,14 +481,15 @@ func (s *memSeries) chunk(id chunks.HeadChunkID, chunkDiskMapper *chunks.ChunkDi
 	return elem, true, offset == 0, nil
 }
 
-// oooMergedChunks return an iterable over one or more OOO chunks for the given
+// mergedChunks return an iterable over one or more OOO chunks for the given
 // chunks.Meta reference from memory or by m-mapping it from the disk. The
 // returned iterable will be a merge of all the overlapping chunks, if any,
 // amongst all the chunks in the OOOHead.
+// If hr is non-nil then in-order chunks are included.
 // This function is not thread safe unless the caller holds a lock.
 // The caller must ensure that s.ooo is not nil.
-func (s *memSeries) oooMergedChunks(meta chunks.Meta, cdm *chunks.ChunkDiskMapper, mint, maxt int64, maxMmapRef chunks.ChunkDiskMapperRef) (*mergedOOOChunks, error) {
-	_, cid := chunks.HeadChunkRef(meta.Ref).Unpack()
+func (s *memSeries) mergedChunks(meta chunks.Meta, cdm *chunks.ChunkDiskMapper, hr *headChunkReader, mint, maxt int64, maxMmapRef chunks.ChunkDiskMapperRef) (chunkenc.Iterable, error) {
+	_, cid, _ := unpackHeadChunkRef(meta.Ref)
 
 	// ix represents the index of chunk in the s.mmappedChunks slice. The chunk meta's are
 	// incremented by 1 when new chunk is created, hence (meta - firstChunkID) gives the slice index.
@@ -509,6 +530,16 @@ func (s *memSeries) oooMergedChunks(meta chunks.Meta, cdm *chunks.ChunkDiskMappe
 		tmpChks = append(tmpChks, chunkMetaAndChunkDiskMapperRef{meta: meta})
 	}
 
+	if hr != nil { // Include in-order chunks.
+		metas := appendSeriesChunks(s, max(meta.MinTime, mint), min(meta.MaxTime, maxt), nil)
+		for _, m := range metas {
+			tmpChks = append(tmpChks, chunkMetaAndChunkDiskMapperRef{
+				meta: m,
+				ref:  0, // This tells the loop below it's an in-order head chunk.
+			})
+		}
+	}
+
 	// Next we want to sort all the collected chunks by min time so we can find
 	// those that overlap and stop when we know the rest don't.
 	slices.SortFunc(tmpChks, refLessByMinTimeAndMinRef)
@@ -520,9 +551,17 @@ func (s *memSeries) oooMergedChunks(meta chunks.Meta, cdm *chunks.ChunkDiskMappe
 			continue
 		}
 		var iterable chunkenc.Iterable
-		if c.meta.Chunk != nil {
+		switch {
+		case c.meta.Chunk != nil:
 			iterable = c.meta.Chunk
-		} else {
+		case c.ref == 0: // This is an in-order head chunk.
+			_, cid := chunks.HeadChunkRef(c.meta.Ref).Unpack()
+			var err error
+			iterable, _, err = hr.chunkFromSeries(s, cid, false)
+			if err != nil {
+				return nil, fmt.Errorf("invalid head chunk: %w", err)
+			}
+		default:
 			chk, err := cdm.Chunk(c.ref)
 			if err != nil {
 				var cerr *chunks.CorruptionErr

tsdb/head_wal.go

@@ -890,7 +890,7 @@ func (wp *wblSubsetProcessor) processWBLSamples(h *Head) (unknownRefs uint64) {
 				unknownRefs++
 				continue
 			}
-			ok, chunkCreated, _ := ms.insert(s.T, s.V, nil, nil, h.chunkDiskMapper, oooCapMax)
+			ok, chunkCreated, _ := ms.insert(s.T, s.V, nil, nil, h.chunkDiskMapper, oooCapMax, h.logger)
 			if chunkCreated {
 				h.metrics.chunksCreated.Inc()
 				h.metrics.chunks.Inc()

tsdb/ooo_head.go

@@ -14,16 +14,10 @@
 package tsdb
 
 import (
-	"fmt"
 	"sort"
 
 	"github.com/prometheus/prometheus/model/histogram"
 	"github.com/prometheus/prometheus/tsdb/chunkenc"
-
-	"github.com/oklog/ulid"
-
-	"github.com/prometheus/prometheus/tsdb/chunks"
-	"github.com/prometheus/prometheus/tsdb/tombstones"
 )
 
 // OOOChunk maintains samples in time-ascending order.
@@ -171,75 +165,3 @@ func (o *OOOChunk) ToEncodedChunks(mint, maxt int64) (chks []memChunk, err error
 	}
 	return chks, nil
 }
-
-var _ BlockReader = &OOORangeHead{}
-
-// OOORangeHead allows querying Head out of order samples via BlockReader
-// interface implementation.
-type OOORangeHead struct {
-	head *Head
-	// mint and maxt are tracked because when a query is handled we only want
-	// the timerange of the query and having preexisting pointers to the first
-	// and last timestamp help with that.
-	mint, maxt int64
-
-	isoState *oooIsolationState
-}
-
-func NewOOORangeHead(head *Head, mint, maxt int64, minRef chunks.ChunkDiskMapperRef) *OOORangeHead {
-	isoState := head.oooIso.TrackReadAfter(minRef)
-
-	return &OOORangeHead{
-		head:     head,
-		mint:     mint,
-		maxt:     maxt,
-		isoState: isoState,
-	}
-}
-
-func (oh *OOORangeHead) Index() (IndexReader, error) {
-	return NewOOOHeadIndexReader(oh.head, oh.mint, oh.maxt, oh.isoState.minRef), nil
-}
-
-func (oh *OOORangeHead) Chunks() (ChunkReader, error) {
-	return NewOOOHeadChunkReader(oh.head, oh.mint, oh.maxt, oh.isoState, 0), nil
-}
-
-func (oh *OOORangeHead) Tombstones() (tombstones.Reader, error) {
-	// As stated in the design doc https://docs.google.com/document/d/1Kppm7qL9C-BJB1j6yb6-9ObG3AbdZnFUBYPNNWwDBYM/edit?usp=sharing
-	// Tombstones are not supported for out of order metrics.
-	return tombstones.NewMemTombstones(), nil
-}
-
-var oooRangeHeadULID = ulid.MustParse("0000000000XXXX000RANGEHEAD")
-
-func (oh *OOORangeHead) Meta() BlockMeta {
-	return BlockMeta{
-		MinTime: oh.mint,
-		MaxTime: oh.maxt,
-		ULID:    oooRangeHeadULID,
-		Stats: BlockStats{
-			NumSeries: oh.head.NumSeries(),
-		},
-	}
-}
-
-// Size returns the size taken by the Head block.
-func (oh *OOORangeHead) Size() int64 {
-	return oh.head.Size()
-}
-
-// String returns an human readable representation of the out of order range
-// head. It's important to keep this function in order to avoid the struct dump
-// when the head is stringified in errors or logs.
-func (oh *OOORangeHead) String() string {
-	return fmt.Sprintf("ooo range head (mint: %d, maxt: %d)", oh.MinTime(), oh.MaxTime())
-}
-
-func (oh *OOORangeHead) MinTime() int64 {
-	return oh.mint
-}
-
-func (oh *OOORangeHead) MaxTime() int64 {
-	return oh.maxt
-}

tsdb/ooo_head_read.go

@@ -27,17 +27,12 @@ import (
 	"github.com/prometheus/prometheus/tsdb/chunks"
 	"github.com/prometheus/prometheus/tsdb/index"
 	"github.com/prometheus/prometheus/tsdb/tombstones"
+	"github.com/prometheus/prometheus/util/annotations"
 )
 
-var _ IndexReader = &OOOHeadIndexReader{}
+var _ IndexReader = &HeadAndOOOIndexReader{}
 
-// OOOHeadIndexReader implements IndexReader so ooo samples in the head can be
-// accessed.
-// It also has a reference to headIndexReader so we can leverage on its
-// IndexReader implementation for all the methods that remain the same. We
-// decided to do this to avoid code duplication.
-// The only methods that change are the ones about getting Series and Postings.
-type OOOHeadIndexReader struct {
+type HeadAndOOOIndexReader struct {
 	*headIndexReader            // A reference to the headIndexReader so we can reuse as many interface implementation as possible.
 	lastGarbageCollectedMmapRef chunks.ChunkDiskMapperRef
 }
@@ -53,25 +48,16 @@ func (o mergedOOOChunks) Iterator(iterator chunkenc.Iterator) chunkenc.Iterator
 	return storage.ChainSampleIteratorFromIterables(iterator, o.chunkIterables)
 }
 
-func NewOOOHeadIndexReader(head *Head, mint, maxt int64, lastGarbageCollectedMmapRef chunks.ChunkDiskMapperRef) *OOOHeadIndexReader {
+func NewHeadAndOOOIndexReader(head *Head, mint, maxt int64, lastGarbageCollectedMmapRef chunks.ChunkDiskMapperRef) *HeadAndOOOIndexReader {
 	hr := &headIndexReader{
 		head: head,
 		mint: mint,
 		maxt: maxt,
 	}
-	return &OOOHeadIndexReader{hr, lastGarbageCollectedMmapRef}
+	return &HeadAndOOOIndexReader{hr, lastGarbageCollectedMmapRef}
 }
 
-func (oh *OOOHeadIndexReader) Series(ref storage.SeriesRef, builder *labels.ScratchBuilder, chks *[]chunks.Meta) error {
-	return oh.series(ref, builder, chks, oh.lastGarbageCollectedMmapRef, 0)
-}
-
-// lastGarbageCollectedMmapRef gives the last mmap chunk that may be being garbage collected and so
-// any chunk at or before this ref will not be considered. 0 disables this check.
-//
-// maxMmapRef tells upto what max m-map chunk that we can consider. If it is non-0, then
-// the oooHeadChunk will not be considered.
-func (oh *OOOHeadIndexReader) series(ref storage.SeriesRef, builder *labels.ScratchBuilder, chks *[]chunks.Meta, lastGarbageCollectedMmapRef, maxMmapRef chunks.ChunkDiskMapperRef) error {
+func (oh *HeadAndOOOIndexReader) Series(ref storage.SeriesRef, builder *labels.ScratchBuilder, chks *[]chunks.Meta) error {
 	s := oh.head.series.getByID(chunks.HeadSeriesRef(ref))
 
 	if s == nil {
@@ -88,10 +74,19 @@ func (oh *OOOHeadIndexReader) series(ref storage.SeriesRef, builder *labels.Scra
 	defer s.Unlock()
 	*chks = (*chks)[:0]
 
-	if s.ooo == nil {
-		return nil
+	if s.ooo != nil {
+		return getOOOSeriesChunks(s, oh.mint, oh.maxt, oh.lastGarbageCollectedMmapRef, 0, true, chks)
 	}
+	*chks = appendSeriesChunks(s, oh.mint, oh.maxt, *chks)
+	return nil
+}
 
+// lastGarbageCollectedMmapRef gives the last mmap chunk that may be being garbage collected and so
+// any chunk at or before this ref will not be considered. 0 disables this check.
+//
+// maxMmapRef tells upto what max m-map chunk that we can consider. If it is non-0, then
+// the oooHeadChunk will not be considered.
+func getOOOSeriesChunks(s *memSeries, mint, maxt int64, lastGarbageCollectedMmapRef, maxMmapRef chunks.ChunkDiskMapperRef, includeInOrder bool, chks *[]chunks.Meta) error {
 	tmpChks := make([]chunks.Meta, 0, len(s.ooo.oooMmappedChunks))
 
 	addChunk := func(minT, maxT int64, ref chunks.ChunkRef, chunk chunkenc.Chunk) {
@@ -106,7 +101,7 @@ func (oh *OOOHeadIndexReader) series(ref storage.SeriesRef, builder *labels.Scra
 	// Collect all chunks that overlap the query range.
 	if s.ooo.oooHeadChunk != nil {
 		c := s.ooo.oooHeadChunk
-		if c.OverlapsClosedInterval(oh.mint, oh.maxt) && maxMmapRef == 0 {
+		if c.OverlapsClosedInterval(mint, maxt) && maxMmapRef == 0 {
 			ref := chunks.ChunkRef(chunks.NewHeadChunkRef(s.ref, s.oooHeadChunkID(len(s.ooo.oooMmappedChunks))))
 			if len(c.chunk.samples) > 0 { // Empty samples happens in tests, at least.
 				chks, err := s.ooo.oooHeadChunk.chunk.ToEncodedChunks(c.minTime, c.maxTime)
@@ -125,12 +120,16 @@ func (oh *OOOHeadIndexReader) series(ref storage.SeriesRef, builder *labels.Scra
 	}
 	for i := len(s.ooo.oooMmappedChunks) - 1; i >= 0; i-- {
 		c := s.ooo.oooMmappedChunks[i]
-		if c.OverlapsClosedInterval(oh.mint, oh.maxt) && (maxMmapRef == 0 || maxMmapRef.GreaterThanOrEqualTo(c.ref)) && (lastGarbageCollectedMmapRef == 0 || c.ref.GreaterThan(lastGarbageCollectedMmapRef)) {
+		if c.OverlapsClosedInterval(mint, maxt) && (maxMmapRef == 0 || maxMmapRef.GreaterThanOrEqualTo(c.ref)) && (lastGarbageCollectedMmapRef == 0 || c.ref.GreaterThan(lastGarbageCollectedMmapRef)) {
 			ref := chunks.ChunkRef(chunks.NewHeadChunkRef(s.ref, s.oooHeadChunkID(i)))
 			addChunk(c.minTime, c.maxTime, ref, nil)
 		}
 	}
 
+	if includeInOrder {
+		tmpChks = appendSeriesChunks(s, mint, maxt, tmpChks)
+	}
+
 	// There is nothing to do if we did not collect any chunk.
 	if len(tmpChks) == 0 {
 		return nil
@@ -167,11 +166,10 @@ func (oh *OOOHeadIndexReader) series(ref storage.SeriesRef, builder *labels.Scra
 	return nil
 }
 
-// LabelValues needs to be overridden from the headIndexReader implementation due
-// to the check that happens at the beginning where we make sure that the query
-// interval overlaps with the head minooot and maxooot.
-func (oh *OOOHeadIndexReader) LabelValues(ctx context.Context, name string, matchers ...*labels.Matcher) ([]string, error) {
-	if oh.maxt < oh.head.MinOOOTime() || oh.mint > oh.head.MaxOOOTime() {
+// LabelValues needs to be overridden from the headIndexReader implementation
+// so we can return labels within either in-order range or ooo range.
+func (oh *HeadAndOOOIndexReader) LabelValues(ctx context.Context, name string, matchers ...*labels.Matcher) ([]string, error) {
+	if oh.maxt < oh.head.MinTime() && oh.maxt < oh.head.MinOOOTime() || oh.mint > oh.head.MaxTime() && oh.mint > oh.head.MaxOOOTime() {
 		return []string{}, nil
 	}
 
@@ -223,41 +221,30 @@ func lessByMinTimeAndMinRef(a, b chunks.Meta) int {
 	}
 }
 
-func (oh *OOOHeadIndexReader) Postings(ctx context.Context, name string, values ...string) (index.Postings, error) {
-	switch len(values) {
-	case 0:
-		return index.EmptyPostings(), nil
-	case 1:
-		return oh.head.postings.Get(name, values[0]), nil // TODO(ganesh) Also call GetOOOPostings
-	default:
-		// TODO(ganesh) We want to only return postings for out of order series.
-		res := make([]index.Postings, 0, len(values))
-		for _, value := range values {
-			res = append(res, oh.head.postings.Get(name, value)) // TODO(ganesh) Also call GetOOOPostings
-		}
-		return index.Merge(ctx, res...), nil
+type HeadAndOOOChunkReader struct {
+	head        *Head
+	mint, maxt  int64
+	cr          *headChunkReader // If nil, only read OOO chunks.
+	maxMmapRef  chunks.ChunkDiskMapperRef
+	oooIsoState *oooIsolationState
+}
+
+func NewHeadAndOOOChunkReader(head *Head, mint, maxt int64, cr *headChunkReader, oooIsoState *oooIsolationState, maxMmapRef chunks.ChunkDiskMapperRef) *HeadAndOOOChunkReader {
+	return &HeadAndOOOChunkReader{
+		head:        head,
+		mint:        mint,
+		maxt:        maxt,
+		cr:          cr,
+		maxMmapRef:  maxMmapRef,
+		oooIsoState: oooIsoState,
 	}
 }
 
-type OOOHeadChunkReader struct {
-	head       *Head
-	mint, maxt int64
-	isoState   *oooIsolationState
-	maxMmapRef chunks.ChunkDiskMapperRef
-}
-
-func NewOOOHeadChunkReader(head *Head, mint, maxt int64, isoState *oooIsolationState, maxMmapRef chunks.ChunkDiskMapperRef) *OOOHeadChunkReader {
-	return &OOOHeadChunkReader{
-		head:       head,
-		mint:       mint,
-		maxt:       maxt,
-		isoState:   isoState,
-		maxMmapRef: maxMmapRef,
+func (cr *HeadAndOOOChunkReader) ChunkOrIterable(meta chunks.Meta) (chunkenc.Chunk, chunkenc.Iterable, error) {
+	sid, _, isOOO := unpackHeadChunkRef(meta.Ref)
+	if !isOOO {
+		return cr.cr.ChunkOrIterable(meta)
 	}
-}
-
-func (cr OOOHeadChunkReader) ChunkOrIterable(meta chunks.Meta) (chunkenc.Chunk, chunkenc.Iterable, error) {
-	sid, _ := chunks.HeadChunkRef(meta.Ref).Unpack()
 
 	s := cr.head.series.getByID(sid)
 	// This means that the series has been garbage collected.
@@ -266,34 +253,35 @@ func (cr OOOHeadChunkReader) ChunkOrIterable(meta chunks.Meta) (chunkenc.Chunk,
 	}
 
 	s.Lock()
-	if s.ooo == nil {
-		// There is no OOO data for this series.
-		s.Unlock()
-		return nil, nil, storage.ErrNotFound
-	}
-	mc, err := s.oooMergedChunks(meta, cr.head.chunkDiskMapper, cr.mint, cr.maxt, cr.maxMmapRef)
+	mc, err := s.mergedChunks(meta, cr.head.chunkDiskMapper, cr.cr, cr.mint, cr.maxt, cr.maxMmapRef)
 	s.Unlock()
-	if err != nil {
-		return nil, nil, err
-	}
 
-	// This means that the query range did not overlap with the requested chunk.
-	if len(mc.chunkIterables) == 0 {
-		return nil, nil, storage.ErrNotFound
-	}
-
-	return nil, mc, nil
+	return nil, mc, err
 }
 
-func (cr OOOHeadChunkReader) Close() error {
-	if cr.isoState != nil {
-		cr.isoState.Close()
+// ChunkOrIterableWithCopy: implements ChunkReaderWithCopy. The special Copy behaviour
+// is only implemented for the in-order head chunk.
+func (cr *HeadAndOOOChunkReader) ChunkOrIterableWithCopy(meta chunks.Meta) (chunkenc.Chunk, chunkenc.Iterable, int64, error) {
+	_, _, isOOO := unpackHeadChunkRef(meta.Ref)
+	if !isOOO {
+		return cr.cr.ChunkOrIterableWithCopy(meta)
+	}
+	chk, iter, err := cr.ChunkOrIterable(meta)
+	return chk, iter, 0, err
+}
+
+func (cr *HeadAndOOOChunkReader) Close() error {
+	if cr.cr != nil && cr.cr.isoState != nil {
+		cr.cr.isoState.Close()
+	}
+	if cr.oooIsoState != nil {
+		cr.oooIsoState.Close()
 	}
 	return nil
 }
 
 type OOOCompactionHead struct {
-	oooIR       *OOOHeadIndexReader
+	head        *Head
 	lastMmapRef chunks.ChunkDiskMapperRef
 	lastWBLFile int
 	postings    []storage.SeriesRef
@@ -310,6 +298,7 @@ type OOOCompactionHead struct {
 // on the sample append latency. So call NewOOOCompactionHead only right before compaction.
 func NewOOOCompactionHead(ctx context.Context, head *Head) (*OOOCompactionHead, error) {
 	ch := &OOOCompactionHead{
+		head:       head,
 		chunkRange: head.chunkRange.Load(),
 		mint:       math.MaxInt64,
 		maxt:       math.MinInt64,
@@ -323,15 +312,14 @@ func NewOOOCompactionHead(ctx context.Context, head *Head) (*OOOCompactionHead,
 		ch.lastWBLFile = lastWBLFile
 	}
 
-	ch.oooIR = NewOOOHeadIndexReader(head, math.MinInt64, math.MaxInt64, 0)
+	hr := headIndexReader{head: head, mint: ch.mint, maxt: ch.maxt}
 	n, v := index.AllPostingsKey()
-
-	// TODO: verify this gets only ooo samples.
-	p, err := ch.oooIR.Postings(ctx, n, v)
+	// TODO: filter to series with OOO samples, before sorting.
+	p, err := hr.Postings(ctx, n, v)
 	if err != nil {
 		return nil, err
 	}
-	p = ch.oooIR.SortedPostings(p)
+	p = hr.SortedPostings(p)
 
 	var lastSeq, lastOff int
 	for p.Next() {
@@ -352,7 +340,7 @@ func NewOOOCompactionHead(ctx context.Context, head *Head) (*OOOCompactionHead,
 		}
 
 		var lastMmapRef chunks.ChunkDiskMapperRef
-		mmapRefs := ms.mmapCurrentOOOHeadChunk(head.chunkDiskMapper)
+		mmapRefs := ms.mmapCurrentOOOHeadChunk(head.chunkDiskMapper, head.logger)
 		if len(mmapRefs) == 0 && len(ms.ooo.oooMmappedChunks) > 0 {
 			// Nothing was m-mapped. So take the mmapRef from the existing slice if it exists.
 			mmapRefs = []chunks.ChunkDiskMapperRef{ms.ooo.oooMmappedChunks[len(ms.ooo.oooMmappedChunks)-1].ref}
@@ -388,7 +376,7 @@ func (ch *OOOCompactionHead) Index() (IndexReader, error) {
 }
 
 func (ch *OOOCompactionHead) Chunks() (ChunkReader, error) {
-	return NewOOOHeadChunkReader(ch.oooIR.head, ch.oooIR.mint, ch.oooIR.maxt, nil, ch.lastMmapRef), nil
+	return NewHeadAndOOOChunkReader(ch.head, ch.mint, ch.maxt, nil, nil, ch.lastMmapRef), nil
 }
 
 func (ch *OOOCompactionHead) Tombstones() (tombstones.Reader, error) {
@@ -414,12 +402,12 @@ func (ch *OOOCompactionHead) Meta() BlockMeta {
 // Only the method of BlockReader interface are valid for the cloned OOOCompactionHead.
 func (ch *OOOCompactionHead) CloneForTimeRange(mint, maxt int64) *OOOCompactionHead {
 	return &OOOCompactionHead{
-		oooIR:       NewOOOHeadIndexReader(ch.oooIR.head, mint, maxt, 0),
+		head:        ch.head,
 		lastMmapRef: ch.lastMmapRef,
 		postings:    ch.postings,
 		chunkRange:  ch.chunkRange,
-		mint:        ch.mint,
-		maxt:        ch.maxt,
+		mint:        mint,
+		maxt:        maxt,
 	}
 }
 
@@ -439,7 +427,8 @@ func NewOOOCompactionHeadIndexReader(ch *OOOCompactionHead) IndexReader {
 }
 
 func (ir *OOOCompactionHeadIndexReader) Symbols() index.StringIter {
-	return ir.ch.oooIR.Symbols()
+	hr := headIndexReader{head: ir.ch.head, mint: ir.ch.mint, maxt: ir.ch.maxt}
+	return hr.Symbols()
 }
 
 func (ir *OOOCompactionHeadIndexReader) Postings(_ context.Context, name string, values ...string) (index.Postings, error) {
@@ -460,11 +449,28 @@ func (ir *OOOCompactionHeadIndexReader) SortedPostings(p index.Postings) index.P
 }
 
 func (ir *OOOCompactionHeadIndexReader) ShardedPostings(p index.Postings, shardIndex, shardCount uint64) index.Postings {
-	return ir.ch.oooIR.ShardedPostings(p, shardIndex, shardCount)
+	hr := headIndexReader{head: ir.ch.head, mint: ir.ch.mint, maxt: ir.ch.maxt}
+	return hr.ShardedPostings(p, shardIndex, shardCount)
 }
 
 func (ir *OOOCompactionHeadIndexReader) Series(ref storage.SeriesRef, builder *labels.ScratchBuilder, chks *[]chunks.Meta) error {
-	return ir.ch.oooIR.series(ref, builder, chks, 0, ir.ch.lastMmapRef)
+	s := ir.ch.head.series.getByID(chunks.HeadSeriesRef(ref))
+
+	if s == nil {
+		ir.ch.head.metrics.seriesNotFound.Inc()
+		return storage.ErrNotFound
+	}
+	builder.Assign(s.labels())
+
+	s.Lock()
+	defer s.Unlock()
+	*chks = (*chks)[:0]
+
+	if s.ooo == nil {
+		return nil
+	}
+
+	return getOOOSeriesChunks(s, ir.ch.mint, ir.ch.maxt, 0, ir.ch.lastMmapRef, false, chks)
 }
 
 func (ir *OOOCompactionHeadIndexReader) SortedLabelValues(_ context.Context, name string, matchers ...*labels.Matcher) ([]string, error) {
@@ -492,5 +498,91 @@ func (ir *OOOCompactionHeadIndexReader) LabelNamesFor(ctx context.Context, posti
 }
 
 func (ir *OOOCompactionHeadIndexReader) Close() error {
-	return ir.ch.oooIR.Close()
+	return nil
+}
+
+// HeadAndOOOQuerier queries both the head and the out-of-order head.
+type HeadAndOOOQuerier struct {
+	mint, maxt int64
+	head       *Head
+	index      IndexReader
+	chunkr     ChunkReader
+	querier    storage.Querier
+}
+
+func NewHeadAndOOOQuerier(mint, maxt int64, head *Head, oooIsoState *oooIsolationState, querier storage.Querier) storage.Querier {
+	cr := &headChunkReader{
+		head:     head,
+		mint:     mint,
+		maxt:     maxt,
+		isoState: head.iso.State(mint, maxt),
+	}
+	return &HeadAndOOOQuerier{
+		mint:    mint,
+		maxt:    maxt,
+		head:    head,
+		index:   NewHeadAndOOOIndexReader(head, mint, maxt, oooIsoState.minRef),
+		chunkr:  NewHeadAndOOOChunkReader(head, mint, maxt, cr, oooIsoState, 0),
+		querier: querier,
+	}
+}
+
+func (q *HeadAndOOOQuerier) LabelValues(ctx context.Context, name string, hints *storage.LabelHints, matchers ...*labels.Matcher) ([]string, annotations.Annotations, error) {
+	return q.querier.LabelValues(ctx, name, hints, matchers...)
+}
+
+func (q *HeadAndOOOQuerier) LabelNames(ctx context.Context, hints *storage.LabelHints, matchers ...*labels.Matcher) ([]string, annotations.Annotations, error) {
+	return q.querier.LabelNames(ctx, hints, matchers...)
+}
+
+func (q *HeadAndOOOQuerier) Close() error {
+	q.chunkr.Close()
+	return q.querier.Close()
+}
+
+func (q *HeadAndOOOQuerier) Select(ctx context.Context, sortSeries bool, hints *storage.SelectHints, matchers ...*labels.Matcher) storage.SeriesSet {
+	return selectSeriesSet(ctx, sortSeries, hints, matchers, q.index, q.chunkr, q.head.tombstones, q.mint, q.maxt)
+}
+
+// HeadAndOOOChunkQuerier queries both the head and the out-of-order head.
+type HeadAndOOOChunkQuerier struct {
+	mint, maxt int64
+	head       *Head
+	index      IndexReader
+	chunkr     ChunkReader
+	querier    storage.ChunkQuerier
+}
+
+func NewHeadAndOOOChunkQuerier(mint, maxt int64, head *Head, oooIsoState *oooIsolationState, querier storage.ChunkQuerier) storage.ChunkQuerier {
+	cr := &headChunkReader{
+		head:     head,
+		mint:     mint,
+		maxt:     maxt,
+		isoState: head.iso.State(mint, maxt),
+	}
+	return &HeadAndOOOChunkQuerier{
+		mint:    mint,
+		maxt:    maxt,
+		head:    head,
+		index:   NewHeadAndOOOIndexReader(head, mint, maxt, oooIsoState.minRef),
+		chunkr:  NewHeadAndOOOChunkReader(head, mint, maxt, cr, oooIsoState, 0),
+		querier: querier,
+	}
+}
+
+func (q *HeadAndOOOChunkQuerier) LabelValues(ctx context.Context, name string, hints *storage.LabelHints, matchers ...*labels.Matcher) ([]string, annotations.Annotations, error) {
+	return q.querier.LabelValues(ctx, name, hints, matchers...)
+}
+
+func (q *HeadAndOOOChunkQuerier) LabelNames(ctx context.Context, hints *storage.LabelHints, matchers ...*labels.Matcher) ([]string, annotations.Annotations, error) {
+	return q.querier.LabelNames(ctx, hints, matchers...)
+}
+
+func (q *HeadAndOOOChunkQuerier) Close() error {
+	q.chunkr.Close()
+	return q.querier.Close()
+}
+
+func (q *HeadAndOOOChunkQuerier) Select(ctx context.Context, sortSeries bool, hints *storage.SelectHints, matchers ...*labels.Matcher) storage.ChunkSeriesSet {
+	return selectChunkSeriesSet(ctx, sortSeries, hints, matchers, rangeHeadULID, q.index, q.chunkr, q.head.tombstones, q.mint, q.maxt)
 }

tsdb/ooo_head_read_test.go

@@ -316,7 +316,7 @@ func TestOOOHeadIndexReader_Series(t *testing.T) {
 						// Ref to whatever Ref the chunk has, that we refer to by ID
 						for ref, c := range intervals {
 							if c.ID == e.ID {
-								meta.Ref = chunks.ChunkRef(chunks.NewHeadChunkRef(chunks.HeadSeriesRef(s1ID), chunks.HeadChunkID(ref)))
+								meta.Ref = chunks.ChunkRef(chunks.NewHeadChunkRef(chunks.HeadSeriesRef(s1ID), s1.oooHeadChunkID(ref)))
 								break
 							}
 						}
@@ -341,7 +341,7 @@ func TestOOOHeadIndexReader_Series(t *testing.T) {
 						})
 					}
 
-					ir := NewOOOHeadIndexReader(h, tc.queryMinT, tc.queryMaxT, 0)
+					ir := NewHeadAndOOOIndexReader(h, tc.queryMinT, tc.queryMaxT, 0)
 
 					var chks []chunks.Meta
 					var b labels.ScratchBuilder
@@ -421,17 +421,17 @@ func testOOOHeadChunkReader_LabelValues(t *testing.T, scenario sampleTypeScenari
 			name:       "LabelValues calls with ooo head query range not overlapping out-of-order data",
 			queryMinT:  100,
 			queryMaxT:  100,
-			expValues1: []string{},
-			expValues2: []string{},
-			expValues3: []string{},
-			expValues4: []string{},
+			expValues1: []string{"bar1"},
+			expValues2: nil,
+			expValues3: []string{"bar1", "bar2"},
+			expValues4: []string{"bar1", "bar2"},
 		},
 	}
 
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
 			// We first want to test using a head index reader that covers the biggest query interval
-			oh := NewOOOHeadIndexReader(head, tc.queryMinT, tc.queryMaxT, 0)
+			oh := NewHeadAndOOOIndexReader(head, tc.queryMinT, tc.queryMaxT, 0)
 			matchers := []*labels.Matcher{labels.MustNewMatcher(labels.MatchEqual, "foo", "bar1")}
 			values, err := oh.LabelValues(ctx, "foo", matchers...)
 			sort.Strings(values)
@@ -481,10 +481,10 @@ func testOOOHeadChunkReader_Chunk(t *testing.T, scenario sampleTypeScenario) {
 	t.Run("Getting a non existing chunk fails with not found error", func(t *testing.T) {
 		db := newTestDBWithOpts(t, opts)
 
-		cr := NewOOOHeadChunkReader(db.head, 0, 1000, nil, 0)
+		cr := NewHeadAndOOOChunkReader(db.head, 0, 1000, nil, nil, 0)
 		defer cr.Close()
 		c, iterable, err := cr.ChunkOrIterable(chunks.Meta{
-			Ref: 0x1000000, Chunk: chunkenc.Chunk(nil), MinTime: 100, MaxTime: 300,
+			Ref: 0x1800000, Chunk: chunkenc.Chunk(nil), MinTime: 100, MaxTime: 300,
 		})
 		require.Nil(t, iterable)
 		require.Equal(t, err, fmt.Errorf("not found"))
@@ -832,14 +832,14 @@ func testOOOHeadChunkReader_Chunk(t *testing.T, scenario sampleTypeScenario) {
 
 			// The Series method populates the chunk metas, taking a copy of the
 			// head OOO chunk if necessary. These are then used by the ChunkReader.
-			ir := NewOOOHeadIndexReader(db.head, tc.queryMinT, tc.queryMaxT, 0)
+			ir := NewHeadAndOOOIndexReader(db.head, tc.queryMinT, tc.queryMaxT, 0)
 			var chks []chunks.Meta
 			var b labels.ScratchBuilder
 			err = ir.Series(s1Ref, &b, &chks)
 			require.NoError(t, err)
 			require.Equal(t, len(tc.expChunksSamples), len(chks))
 
-			cr := NewOOOHeadChunkReader(db.head, tc.queryMinT, tc.queryMaxT, nil, 0)
+			cr := NewHeadAndOOOChunkReader(db.head, tc.queryMinT, tc.queryMaxT, nil, nil, 0)
 			defer cr.Close()
 			for i := 0; i < len(chks); i++ {
 				c, iterable, err := cr.ChunkOrIterable(chks[i])
@@ -997,7 +997,7 @@ func testOOOHeadChunkReader_Chunk_ConsistentQueryResponseDespiteOfHeadExpanding(
 
 			// The Series method populates the chunk metas, taking a copy of the
 			// head OOO chunk if necessary. These are then used by the ChunkReader.
-			ir := NewOOOHeadIndexReader(db.head, tc.queryMinT, tc.queryMaxT, 0)
+			ir := NewHeadAndOOOIndexReader(db.head, tc.queryMinT, tc.queryMaxT, 0)
 			var chks []chunks.Meta
 			var b labels.ScratchBuilder
 			err = ir.Series(s1Ref, &b, &chks)
@@ -1013,7 +1013,7 @@ func testOOOHeadChunkReader_Chunk_ConsistentQueryResponseDespiteOfHeadExpanding(
 			}
 			require.NoError(t, app.Commit())
 
-			cr := NewOOOHeadChunkReader(db.head, tc.queryMinT, tc.queryMaxT, nil, 0)
+			cr := NewHeadAndOOOChunkReader(db.head, tc.queryMinT, tc.queryMaxT, nil, nil, 0)
 			defer cr.Close()
 			for i := 0; i < len(chks); i++ {
 				c, iterable, err := cr.ChunkOrIterable(chks[i])

tsdb/querier.go

@@ -115,20 +115,24 @@ func NewBlockQuerier(b BlockReader, mint, maxt int64) (storage.Querier, error) {
 }
 
 func (q *blockQuerier) Select(ctx context.Context, sortSeries bool, hints *storage.SelectHints, ms ...*labels.Matcher) storage.SeriesSet {
-	mint := q.mint
-	maxt := q.maxt
+	return selectSeriesSet(ctx, sortSeries, hints, ms, q.index, q.chunks, q.tombstones, q.mint, q.maxt)
+}
+
+func selectSeriesSet(ctx context.Context, sortSeries bool, hints *storage.SelectHints, ms []*labels.Matcher,
+	index IndexReader, chunks ChunkReader, tombstones tombstones.Reader, mint, maxt int64,
+) storage.SeriesSet {
 	disableTrimming := false
 	sharded := hints != nil && hints.ShardCount > 0
 
-	p, err := PostingsForMatchers(ctx, q.index, ms...)
+	p, err := PostingsForMatchers(ctx, index, ms...)
 	if err != nil {
 		return storage.ErrSeriesSet(err)
 	}
 	if sharded {
-		p = q.index.ShardedPostings(p, hints.ShardIndex, hints.ShardCount)
+		p = index.ShardedPostings(p, hints.ShardIndex, hints.ShardCount)
 	}
 	if sortSeries {
-		p = q.index.SortedPostings(p)
+		p = index.SortedPostings(p)
 	}
 
 	if hints != nil {
@@ -137,11 +141,11 @@ func (q *blockQuerier) Select(ctx context.Context, sortSeries bool, hints *stora
 		disableTrimming = hints.DisableTrimming
 		if hints.Func == "series" {
 			// When you're only looking up metadata (for example series API), you don't need to load any chunks.
-			return newBlockSeriesSet(q.index, newNopChunkReader(), q.tombstones, p, mint, maxt, disableTrimming)
+			return newBlockSeriesSet(index, newNopChunkReader(), tombstones, p, mint, maxt, disableTrimming)
 		}
 	}
 
-	return newBlockSeriesSet(q.index, q.chunks, q.tombstones, p, mint, maxt, disableTrimming)
+	return newBlockSeriesSet(index, chunks, tombstones, p, mint, maxt, disableTrimming)
 }
 
 // blockChunkQuerier provides chunk querying access to a single block database.
@@ -159,8 +163,12 @@ func NewBlockChunkQuerier(b BlockReader, mint, maxt int64) (storage.ChunkQuerier
 }
 
 func (q *blockChunkQuerier) Select(ctx context.Context, sortSeries bool, hints *storage.SelectHints, ms ...*labels.Matcher) storage.ChunkSeriesSet {
-	mint := q.mint
-	maxt := q.maxt
+	return selectChunkSeriesSet(ctx, sortSeries, hints, ms, q.blockID, q.index, q.chunks, q.tombstones, q.mint, q.maxt)
+}
+
+func selectChunkSeriesSet(ctx context.Context, sortSeries bool, hints *storage.SelectHints, ms []*labels.Matcher,
+	blockID ulid.ULID, index IndexReader, chunks ChunkReader, tombstones tombstones.Reader, mint, maxt int64,
+) storage.ChunkSeriesSet {
 	disableTrimming := false
 	sharded := hints != nil && hints.ShardCount > 0
 
@@ -169,17 +177,17 @@ func (q *blockChunkQuerier) Select(ctx context.Context, sortSeries bool, hints *
 		maxt = hints.End
 		disableTrimming = hints.DisableTrimming
 	}
-	p, err := PostingsForMatchers(ctx, q.index, ms...)
+	p, err := PostingsForMatchers(ctx, index, ms...)
 	if err != nil {
 		return storage.ErrChunkSeriesSet(err)
 	}
 	if sharded {
-		p = q.index.ShardedPostings(p, hints.ShardIndex, hints.ShardCount)
+		p = index.ShardedPostings(p, hints.ShardIndex, hints.ShardCount)
 	}
 	if sortSeries {
-		p = q.index.SortedPostings(p)
+		p = index.SortedPostings(p)
 	}
-	return NewBlockChunkSeriesSet(q.blockID, q.index, q.chunks, q.tombstones, p, mint, maxt, disableTrimming)
+	return NewBlockChunkSeriesSet(blockID, index, chunks, tombstones, p, mint, maxt, disableTrimming)
 }
 
 // PostingsForMatchers assembles a single postings iterator against the index reader
@@ -633,14 +641,16 @@ func (p *populateWithDelGenericSeriesIterator) next(copyHeadChunk bool) bool {
 		}
 	}
 
-	hcr, ok := p.cr.(*headChunkReader)
+	hcr, ok := p.cr.(ChunkReaderWithCopy)
 	var iterable chunkenc.Iterable
 	if ok && copyHeadChunk && len(p.bufIter.Intervals) == 0 {
-		// ChunkWithCopy will copy the head chunk.
+		// ChunkOrIterableWithCopy will copy the head chunk, if it can.
 		var maxt int64
-		p.currMeta.Chunk, maxt, p.err = hcr.ChunkWithCopy(p.currMeta)
-		// For the in-memory head chunk the index reader sets maxt as MaxInt64. We fix it here.
-		p.currMeta.MaxTime = maxt
+		p.currMeta.Chunk, iterable, maxt, p.err = hcr.ChunkOrIterableWithCopy(p.currMeta)
+		if p.currMeta.Chunk != nil {
+			// For the in-memory head chunk the index reader sets maxt as MaxInt64. We fix it here.
+			p.currMeta.MaxTime = maxt
+		}
 	} else {
 		p.currMeta.Chunk, iterable, p.err = p.cr.ChunkOrIterable(p.currMeta)
 	}

tsdb/querier_bench_test.go

@@ -20,6 +20,7 @@ import (
 	"testing"
 
 	"github.com/prometheus/prometheus/model/labels"
+	"github.com/prometheus/prometheus/storage"
 	"github.com/prometheus/prometheus/tsdb/index"
 
 	"github.com/stretchr/testify/require"
@@ -254,56 +255,98 @@ func BenchmarkMergedStringIter(b *testing.B) {
 	b.ReportAllocs()
 }
 
-func BenchmarkQuerierSelect(b *testing.B) {
-	opts := DefaultHeadOptions()
-	opts.ChunkRange = 1000
-	opts.ChunkDirRoot = b.TempDir()
-	h, err := NewHead(nil, nil, nil, nil, opts, nil)
+func createHeadForBenchmarkSelect(b *testing.B, numSeries int, addSeries func(app storage.Appender, i int)) (*Head, *DB) {
+	dir := b.TempDir()
+	opts := DefaultOptions()
+	opts.OutOfOrderCapMax = 255
+	opts.OutOfOrderTimeWindow = 1000
+	db, err := Open(dir, nil, nil, opts, nil)
 	require.NoError(b, err)
-	defer h.Close()
+	b.Cleanup(func() {
+		require.NoError(b, db.Close())
+	})
+	h := db.Head()
+
 	app := h.Appender(context.Background())
-	numSeries := 1000000
 	for i := 0; i < numSeries; i++ {
-		app.Append(0, labels.FromStrings("foo", "bar", "i", fmt.Sprintf("%d%s", i, postingsBenchSuffix)), int64(i), 0)
+		addSeries(app, i)
 	}
 	require.NoError(b, app.Commit())
+	return h, db
+}
 
-	bench := func(b *testing.B, br BlockReader, sorted bool) {
-		matcher := labels.MustNewMatcher(labels.MatchEqual, "foo", "bar")
-		for s := 1; s <= numSeries; s *= 10 {
-			b.Run(fmt.Sprintf("%dof%d", s, numSeries), func(b *testing.B) {
-				q, err := NewBlockQuerier(br, 0, int64(s-1))
-				require.NoError(b, err)
+func benchmarkSelect(b *testing.B, queryable storage.Queryable, numSeries int, sorted bool) {
+	matcher := labels.MustNewMatcher(labels.MatchEqual, "foo", "bar")
+	b.ResetTimer()
+	for s := 1; s <= numSeries; s *= 10 {
+		b.Run(fmt.Sprintf("%dof%d", s, numSeries), func(b *testing.B) {
+			q, err := queryable.Querier(0, int64(s-1))
+			require.NoError(b, err)
 
-				b.ResetTimer()
-				for i := 0; i < b.N; i++ {
-					ss := q.Select(context.Background(), sorted, nil, matcher)
-					for ss.Next() {
-					}
-					require.NoError(b, ss.Err())
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				ss := q.Select(context.Background(), sorted, nil, matcher)
+				for ss.Next() {
 				}
-				q.Close()
-			})
-		}
+				require.NoError(b, ss.Err())
+			}
+			q.Close()
+		})
 	}
+}
+
+func BenchmarkQuerierSelect(b *testing.B) {
+	numSeries := 1000000
+	h, db := createHeadForBenchmarkSelect(b, numSeries, func(app storage.Appender, i int) {
+		_, err := app.Append(0, labels.FromStrings("foo", "bar", "i", fmt.Sprintf("%d%s", i, postingsBenchSuffix)), int64(i), 0)
+		if err != nil {
+			b.Fatal(err)
+		}
+	})
 
 	b.Run("Head", func(b *testing.B) {
-		bench(b, h, false)
+		benchmarkSelect(b, db, numSeries, false)
 	})
 	b.Run("SortedHead", func(b *testing.B) {
-		bench(b, h, true)
+		benchmarkSelect(b, db, numSeries, true)
 	})
 
-	tmpdir := b.TempDir()
-
-	blockdir := createBlockFromHead(b, tmpdir, h)
-	block, err := OpenBlock(nil, blockdir, nil)
-	require.NoError(b, err)
-	defer func() {
-		require.NoError(b, block.Close())
-	}()
-
 	b.Run("Block", func(b *testing.B) {
-		bench(b, block, false)
+		tmpdir := b.TempDir()
+
+		blockdir := createBlockFromHead(b, tmpdir, h)
+		block, err := OpenBlock(nil, blockdir, nil)
+		require.NoError(b, err)
+		defer func() {
+			require.NoError(b, block.Close())
+		}()
+
+		benchmarkSelect(b, (*queryableBlock)(block), numSeries, false)
+	})
+}
+
+// Type wrapper to let a Block be a Queryable in benchmarkSelect().
+type queryableBlock Block
+
+func (pb *queryableBlock) Querier(mint, maxt int64) (storage.Querier, error) {
+	return NewBlockQuerier((*Block)(pb), mint, maxt)
+}
+
+func BenchmarkQuerierSelectWithOutOfOrder(b *testing.B) {
+	numSeries := 1000000
+	_, db := createHeadForBenchmarkSelect(b, numSeries, func(app storage.Appender, i int) {
+		l := labels.FromStrings("foo", "bar", "i", fmt.Sprintf("%d%s", i, postingsBenchSuffix))
+		ref, err := app.Append(0, l, int64(i+1), 0)
+		if err != nil {
+			b.Fatal(err)
+		}
+		_, err = app.Append(ref, l, int64(i), 1) // Out of order sample
+		if err != nil {
+			b.Fatal(err)
+		}
+	})
+
+	b.Run("Head", func(b *testing.B) {
+		benchmarkSelect(b, db, numSeries, false)
 	})
 }

tsdb/querier_test.go

@@ -3169,12 +3169,11 @@ func BenchmarkQueries(b *testing.B) {
 
 					qHead, err := NewBlockQuerier(NewRangeHead(head, 1, nSamples), 1, nSamples)
 					require.NoError(b, err)
-					qOOOHead, err := NewBlockQuerier(NewOOORangeHead(head, 1, nSamples, 0), 1, nSamples)
-					require.NoError(b, err)
+					isoState := head.oooIso.TrackReadAfter(0)
+					qOOOHead := NewHeadAndOOOQuerier(1, nSamples, head, isoState, qHead)
 
 					queryTypes = append(queryTypes, qt{
-						fmt.Sprintf("_Head_oooPercent:%d", oooPercentage),
-						storage.NewMergeQuerier([]storage.Querier{qHead, qOOOHead}, nil, storage.ChainedSeriesMerge),
+						fmt.Sprintf("_Head_oooPercent:%d", oooPercentage), qOOOHead,
 					})
 				}