Select series with label unset for != and !~

Fixes https://github.com/prometheus/prometheus/issues/3575

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>
Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>

block.go

@@ -289,7 +289,7 @@ func (pb *Block) Delete(mint, maxt int64, ms ...labels.Matcher) error {
 		return ErrClosing
 	}
 
-	p, absent, err := PostingsForMatchers(pb.indexr, ms...)
+	p, err := PostingsForMatchers(pb.indexr, ms...)
 	if err != nil {
 		return errors.Wrap(err, "select series")
 	}
@@ -309,12 +309,6 @@ Outer:
 			return err
 		}
 
-		for _, abs := range absent {
-			if lset.Get(abs) != "" {
-				continue Outer
-			}
-		}
-
 		for _, chk := range chks {
 			if intervalOverlap(mint, maxt, chk.MinTime, chk.MaxTime) {
 				// Delete only until the current vlaues and not beyond.

db_test.go

@@ -807,3 +807,89 @@ func TestDB_Retention(t *testing.T) {
 	testutil.Equals(t, 1, len(db.blocks))
 	testutil.Equals(t, int64(100), db.blocks[0].meta.MaxTime) // To verify its the right block.
 }
+
+func TestNotMatcherSelectsLabelsUnsetSeries(t *testing.T) {
+	tmpdir, _ := ioutil.TempDir("", "test")
+	defer os.RemoveAll(tmpdir)
+
+	db, err := Open(tmpdir, nil, nil, nil)
+	testutil.Ok(t, err)
+	defer db.Close()
+
+	labelpairs := []labels.Labels{
+		labels.FromStrings("a", "abcd", "b", "abcde"),
+		labels.FromStrings("labelname", "labelvalue"),
+	}
+
+	app := db.Appender()
+	for _, lbls := range labelpairs {
+		_, err = app.Add(lbls, 0, 1)
+		testutil.Ok(t, err)
+	}
+	testutil.Ok(t, app.Commit())
+
+	cases := []struct {
+		selector labels.Selector
+		series   []labels.Labels
+	}{{
+		selector: labels.Selector{
+			labels.Not(labels.NewEqualMatcher("lname", "lvalue")),
+		},
+		series: labelpairs,
+	}, {
+		selector: labels.Selector{
+			labels.NewEqualMatcher("a", "abcd"),
+			labels.Not(labels.NewEqualMatcher("b", "abcde")),
+		},
+		series: []labels.Labels{},
+	}, {
+		selector: labels.Selector{
+			labels.NewEqualMatcher("a", "abcd"),
+			labels.Not(labels.NewEqualMatcher("b", "abc")),
+		},
+		series: []labels.Labels{labelpairs[0]},
+	}, {
+		selector: labels.Selector{
+			labels.Not(labels.NewMustRegexpMatcher("a", "abd.*")),
+		},
+		series: labelpairs,
+	}, {
+		selector: labels.Selector{
+			labels.Not(labels.NewMustRegexpMatcher("a", "abc.*")),
+		},
+		series: labelpairs[1:],
+	}, {
+		selector: labels.Selector{
+			labels.Not(labels.NewMustRegexpMatcher("c", "abd.*")),
+		},
+		series: labelpairs,
+	}, {
+		selector: labels.Selector{
+			labels.Not(labels.NewMustRegexpMatcher("labelname", "labelvalue")),
+		},
+		series: labelpairs[:1],
+	}}
+
+	q, err := db.Querier(0, 10)
+	testutil.Ok(t, err)
+	defer q.Close()
+
+	for _, c := range cases {
+		ss, err := q.Select(c.selector...)
+		testutil.Ok(t, err)
+
+		lres, err := expandSeriesSet(ss)
+		testutil.Ok(t, err)
+
+		testutil.Equals(t, c.series, lres)
+	}
+}
+
+func expandSeriesSet(ss SeriesSet) ([]labels.Labels, error) {
+	result := []labels.Labels{}
+	for ss.Next() {
+		result = append(result, ss.At().Labels())
+	}
+
+	return result, ss.Err()
+}

head.go

@@ -574,23 +574,16 @@ func (h *Head) Delete(mint, maxt int64, ms ...labels.Matcher) error {
 
 	ir := h.indexRange(mint, maxt)
 
-	p, absent, err := PostingsForMatchers(ir, ms...)
+	p, err := PostingsForMatchers(ir, ms...)
 	if err != nil {
 		return errors.Wrap(err, "select series")
 	}
 
 	var stones []Stone
 
-Outer:
 	for p.Next() {
 		series := h.series.getByID(p.At())
 
-		for _, abs := range absent {
-			if series.lset.Get(abs) != "" {
-				continue Outer
-			}
-		}
-
 		// Delete only until the current values and not beyond.
 		t0, t1 := clampInterval(mint, maxt, series.minTime(), series.maxTime())
 		stones = append(stones, Stone{p.At(), Intervals{{t0, t1}}})

labels/selector.go

@@ -76,6 +76,18 @@ func NewRegexpMatcher(name, pattern string) (Matcher, error) {
 	return &regexpMatcher{name: name, re: re}, nil
 }
 
+// NewRegexpMatcher returns a new matcher verifying that a value matches
+// the regular expression pattern. Will panic if the pattern is not a valid
+// regular expression.
+func NewMustRegexpMatcher(name, pattern string) Matcher {
+	re, err := regexp.Compile(pattern)
+	if err != nil {
+		panic(err)
+	}
+	return &regexpMatcher{name: name, re: re}
+
+}
+
 // notMatcher inverts the matching result for a matcher.
 type notMatcher struct {
 	Matcher

postings.go

@@ -259,7 +259,7 @@ func (it *intersectPostings) Err() error {
 // Merge returns a new iterator over the union of the input iterators.
 func Merge(its ...Postings) Postings {
 	if len(its) == 0 {
-		return nil
+		return EmptyPostings()
 	}
 	if len(its) == 1 {
 		return its[0]
@@ -340,6 +340,80 @@ func (it *mergedPostings) Err() error {
 	return it.b.Err()
 }
 
+type removedPostings struct {
+	full, remove Postings
+
+	cur uint64
+
+	initialized bool
+	fok, rok    bool
+}
+
+func newRemovedPostings(full, remove Postings) *removedPostings {
+	return &removedPostings{
+		full:   full,
+		remove: remove,
+	}
+}
+
+func (rp *removedPostings) At() uint64 {
+	return rp.cur
+}
+
+func (rp *removedPostings) Next() bool {
+	if !rp.initialized {
+		rp.fok = rp.full.Next()
+		rp.rok = rp.remove.Next()
+		rp.initialized = true
+	}
+
+	if !rp.fok {
+		return false
+	}
+
+	if !rp.rok {
+		rp.cur = rp.full.At()
+		rp.fok = rp.full.Next()
+		return true
+	}
+
+	fcur, rcur := rp.full.At(), rp.remove.At()
+	if fcur < rcur {
+		rp.cur = fcur
+		rp.fok = rp.full.Next()
+
+		return true
+	} else if rcur < fcur {
+		// Forward the remove postings to the right position.
+		rp.rok = rp.remove.Seek(fcur)
+	} else {
+		// Skip the current posting.
+		rp.fok = rp.full.Next()
+	}
+
+	return rp.Next()
+}
+
+func (rp *removedPostings) Seek(id uint64) bool {
+	if rp.cur >= id {
+		return true
+	}
+
+	rp.fok = rp.full.Seek(id)
+	rp.rok = rp.remove.Seek(id)
+	rp.initialized = true
+
+	return rp.Next()
+}
+
+func (rp *removedPostings) Err() error {
+	if rp.full.Err() != nil {
+		return rp.full.Err()
+	}
+
+	return rp.remove.Err()
+}
+
 // listPostings implements the Postings interface over a plain list.
 type listPostings struct {
 	list []uint64

postings_test.go

@@ -301,6 +301,147 @@ func TestMergedPostingsSeek(t *testing.T) {
 	return
 }
 
+func TestRemovedPostings(t *testing.T) {
+	var cases = []struct {
+		a, b []uint64
+		res  []uint64
+	}{
+		{
+			a:   nil,
+			b:   nil,
+			res: []uint64(nil),
+		},
+		{
+			a:   []uint64{1, 2, 3, 4},
+			b:   nil,
+			res: []uint64{1, 2, 3, 4},
+		},
+		{
+			a:   nil,
+			b:   []uint64{1, 2, 3, 4},
+			res: []uint64(nil),
+		},
+		{
+			a:   []uint64{1, 2, 3, 4, 5},
+			b:   []uint64{6, 7, 8, 9, 10},
+			res: []uint64{1, 2, 3, 4, 5},
+		},
+		{
+			a:   []uint64{1, 2, 3, 4, 5},
+			b:   []uint64{4, 5, 6, 7, 8},
+			res: []uint64{1, 2, 3},
+		},
+		{
+			a:   []uint64{1, 2, 3, 4, 9, 10},
+			b:   []uint64{1, 4, 5, 6, 7, 8, 10, 11},
+			res: []uint64{2, 3, 9},
+		},
+		{
+			a:   []uint64{1, 2, 3, 4, 9, 10},
+			b:   []uint64{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11},
+			res: []uint64(nil),
+		},
+	}
+
+	for _, c := range cases {
+		a := newListPostings(c.a)
+		b := newListPostings(c.b)
+
+		res, err := expandPostings(newRemovedPostings(a, b))
+		testutil.Ok(t, err)
+		testutil.Equals(t, c.res, res)
+	}
+
+}
+
+func TestRemovedPostingsSeek(t *testing.T) {
+	var cases = []struct {
+		a, b []uint64
+
+		seek    uint64
+		success bool
+		res     []uint64
+	}{
+		{
+			a: []uint64{2, 3, 4, 5},
+			b: []uint64{6, 7, 8, 9, 10},
+
+			seek:    1,
+			success: true,
+			res:     []uint64{2, 3, 4, 5},
+		},
+		{
+			a: []uint64{1, 2, 3, 4, 5},
+			b: []uint64{6, 7, 8, 9, 10},
+
+			seek:    2,
+			success: true,
+			res:     []uint64{2, 3, 4, 5},
+		},
+		{
+			a: []uint64{1, 2, 3, 4, 5},
+			b: []uint64{4, 5, 6, 7, 8},
+
+			seek:    9,
+			success: false,
+			res:     nil,
+		},
+		{
+			a: []uint64{1, 2, 3, 4, 9, 10},
+			b: []uint64{1, 4, 5, 6, 7, 8, 10, 11},
+
+			seek:    10,
+			success: false,
+			res:     nil,
+		},
+		{
+			a: []uint64{1, 2, 3, 4, 9, 10},
+			b: []uint64{1, 4, 5, 6, 7, 8, 11},
+
+			seek:    4,
+			success: true,
+			res:     []uint64{9, 10},
+		},
+		{
+			a: []uint64{1, 2, 3, 4, 9, 10},
+			b: []uint64{1, 4, 5, 6, 7, 8, 11},
+
+			seek:    5,
+			success: true,
+			res:     []uint64{9, 10},
+		},
+		{
+			a: []uint64{1, 2, 3, 4, 9, 10},
+			b: []uint64{1, 4, 5, 6, 7, 8, 11},
+
+			seek:    10,
+			success: true,
+			res:     []uint64{10},
+		},
+	}
+
+	for _, c := range cases {
+		a := newListPostings(c.a)
+		b := newListPostings(c.b)
+
+		p := newRemovedPostings(a, b)
+
+		testutil.Equals(t, c.success, p.Seek(c.seek))
+
+		// After Seek(), At() should be called.
+		if c.success {
+			start := p.At()
+			lst, err := expandPostings(p)
+			testutil.Ok(t, err)
+
+			lst = append([]uint64{start}, lst...)
+			testutil.Equals(t, c.res, lst)
+		}
+	}
+
+	return
+}
+
 func TestBigEndian(t *testing.T) {
 	num := 1000
 	// mock a list as postings

querier.go

@@ -202,25 +202,18 @@ func (q *blockQuerier) Close() error {
 // PostingsForMatchers assembles a single postings iterator against the index reader
 // based on the given matchers. It returns a list of label names that must be manually
 // checked to not exist in series the postings list points to.
-func PostingsForMatchers(index IndexReader, ms ...labels.Matcher) (Postings, []string, error) {
+func PostingsForMatchers(index IndexReader, ms ...labels.Matcher) (Postings, error) {
 	var (
 		its []Postings
-		absent []string
 	)
 	for _, m := range ms {
-		// If the matcher checks absence of a label, don't select them
-		// but propagate the check into the series set.
-		if _, ok := m.(*labels.EqualMatcher); ok && m.Matches("") {
-			absent = append(absent, m.Name())
-			continue
-		}
 		it, err := postingsForMatcher(index, m)
 		if err != nil {
-			return nil, nil, err
+			return nil, err
 		}
 		its = append(its, it)
 	}
-	return index.SortedPostings(Intersect(its...)), absent, nil
+	return index.SortedPostings(Intersect(its...)), nil
 }
 
 // tuplesByPrefix uses binary search to find prefix matches within ts.
@@ -255,6 +248,13 @@ func tuplesByPrefix(m *labels.PrefixMatcher, ts StringTuples) ([]string, error)
 }
 
 func postingsForMatcher(index IndexReader, m labels.Matcher) (Postings, error) {
+	// If the matcher selects an empty value, it selects all the series which dont
+	// have the label name set too. See: https://github.com/prometheus/prometheus/issues/3575
+	// and https://github.com/prometheus/prometheus/pull/3578#issuecomment-351653555
+	if m.Matches("") {
+		return postingsForUnsetLabelMatcher(index, m)
+	}
+
 	// Fast-path for equal matching.
 	if em, ok := m.(*labels.EqualMatcher); ok {
 		it, err := index.Postings(em.Name(), em.Value())
@@ -305,6 +305,43 @@ func postingsForMatcher(index IndexReader, m labels.Matcher) (Postings, error) {
 	return Merge(rit...), nil
 }
 
+func postingsForUnsetLabelMatcher(index IndexReader, m labels.Matcher) (Postings, error) {
+	tpls, err := index.LabelValues(m.Name())
+	if err != nil {
+		return nil, err
+	}
+
+	var res []string
+	for i := 0; i < tpls.Len(); i++ {
+		vals, err := tpls.At(i)
+		if err != nil {
+			return nil, err
+		}
+
+		if !m.Matches(vals[0]) {
+			res = append(res, vals[0])
+		}
+	}
+
+	var rit []Postings
+	for _, v := range res {
+		it, err := index.Postings(m.Name(), v)
+		if err != nil {
+			return nil, err
+		}
+
+		rit = append(rit, it)
+	}
+	mrit := Merge(rit...)
+
+	allPostings, err := index.Postings(allPostingsKey.Name, allPostingsKey.Value)
+	if err != nil {
+		return nil, err
+	}
+
+	return newRemovedPostings(allPostings, mrit), nil
+}
+
 func mergeStrings(a, b []string) []string {
 	maxl := len(a)
 	if len(b) > len(a) {
@@ -417,6 +454,8 @@ func (s *mergedSeriesSet) Next() bool {
 	return true
 }
 
+// ChunkSeriesSet exposes the chunks and intervals of a series instead of the
+// actual series itself.
 type ChunkSeriesSet interface {
 	Next() bool
 	At() (labels.Labels, []ChunkMeta, Intervals)
@@ -429,7 +468,6 @@ type baseChunkSeries struct {
 	p          Postings
 	index      IndexReader
 	tombstones TombstoneReader
-	absent     []string // labels that must be unset in results.
 
 	lset      labels.Labels
 	chks      []ChunkMeta
@@ -443,7 +481,7 @@ func LookupChunkSeries(ir IndexReader, tr TombstoneReader, ms ...labels.Matcher)
 	if tr == nil {
 		tr = EmptyTombstoneReader()
 	}
-	p, absent, err := PostingsForMatchers(ir, ms...)
+	p, err := PostingsForMatchers(ir, ms...)
 	if err != nil {
 		return nil, err
 	}
@@ -451,7 +489,6 @@ func LookupChunkSeries(ir IndexReader, tr TombstoneReader, ms ...labels.Matcher)
 		p:          p,
 		index:      ir,
 		tombstones: tr,
-		absent:     absent,
 	}, nil
 }
 
@@ -467,7 +504,7 @@ func (s *baseChunkSeries) Next() bool {
 		chunks []ChunkMeta
 		err    error
 	)
-Outer:
+
 	for s.p.Next() {
 		ref := s.p.At()
 		if err := s.index.Series(ref, &lset, &chunks); err != nil {
@@ -479,13 +516,6 @@ Outer:
 			return false
 		}
 
-		// If a series contains a label that must be absent, it is skipped as well.
-		for _, abs := range s.absent {
-			if lset.Get(abs) != "" {
-				continue Outer
-			}
-		}
-
 		s.lset = lset
 		s.chks = chunks
 		s.intervals, err = s.tombstones.Get(s.p.At())