optimize to posting group label value matching

pkg/store/bucket.go

@@ -2725,8 +2725,11 @@ func matchersToPostingGroups(ctx context.Context, lvalsFn func(name string) ([]s
 		matchers := make([]*labels.Matcher, 0, len(vals))
 		// Merge PostingGroups with the same matcher into 1 to
 		// avoid fetching duplicate postings.
+		cnt := 0
 		for _, val := range values {
-			pg, vals, err = toPostingGroup(ctx, lvalsFunc, val)
+			cnt++
+			// We can only reuse the values if the values won't be reused anymore.
+			pg, vals, err = toPostingGroup(ctx, lvalsFunc, val, cnt == len(values))
 			if err != nil {
 				return nil, errors.Wrap(err, "toPostingGroup")
 			}
@@ -2770,13 +2773,11 @@ func matchersToPostingGroups(ctx context.Context, lvalsFn func(name string) ([]s
 }
 
 // NOTE: Derived from tsdb.postingsForMatcher. index.Merge is equivalent to map duplication.
-func toPostingGroup(ctx context.Context, lvalsFn func(name string) ([]string, error), m *labels.Matcher) (*postingGroup, []string, error) {
+func toPostingGroup(ctx context.Context, lvalsFn func(name string) ([]string, error), m *labels.Matcher, reuseValues bool) (*postingGroup, []string, error) {
 	// If the matcher selects an empty value, it selects all the series which don't
 	// 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("") {
-		var toRemove []string
-
 		// Fast-path for MatchNotRegexp matching.
 		// Inverse of a MatchNotRegexp is MatchRegexp (double negation).
 		// Fast-path for set matching.
@@ -2798,12 +2799,22 @@ func toPostingGroup(ctx context.Context, lvalsFn func(name string) ([]string, er
 			return nil, nil, err
 		}
 
-		for _, val := range vals {
-			if ctx.Err() != nil {
-				return nil, nil, ctx.Err()
-			}
-			if !m.Matches(val) {
-				toRemove = append(toRemove, val)
+		var toRemove []string
+		if reuseValues {
+			toRemove = vals[:0]
+		}
+		// If equal matcher matches an empty string, shortcut all values since label
+		// values should always be non-empty string.
+		if m.Value == "" && (m.Type == labels.MatchRegexp || m.Type == labels.MatchEqual) {
+			toRemove = vals
+		} else {
+			for _, val := range vals {
+				if ctx.Err() != nil {
+					return nil, nil, ctx.Err()
+				}
+				if !m.Matches(val) {
+					toRemove = append(toRemove, val)
+				}
 			}
 		}
 
@@ -2827,12 +2838,21 @@ func toPostingGroup(ctx context.Context, lvalsFn func(name string) ([]string, er
 	}
 
 	var toAdd []string
-	for _, val := range vals {
-		if ctx.Err() != nil {
-			return nil, nil, ctx.Err()
-		}
-		if m.Matches(val) {
-			toAdd = append(toAdd, val)
+	if reuseValues {
+		toAdd = vals[:0]
+	}
+	// If non-equal matcher matches a non-empty string, shortcut all values since label
+	// values should always be non-empty string.
+	if m.Value == "" && (m.Type == labels.MatchNotRegexp || m.Type == labels.MatchNotEqual) {
+		toAdd = vals
+	} else {
+		for _, val := range vals {
+			if ctx.Err() != nil {
+				return nil, nil, ctx.Err()
+			}
+			if m.Matches(val) {
+				toAdd = append(toAdd, val)
+			}
 		}
 	}
 

pkg/store/bucket_test.go

@@ -14,7 +14,6 @@ import (
 	"os"
 	"path"
 	"path/filepath"
-	"reflect"
 	"regexp"
 	"sort"
 	"strconv"
@@ -2953,9 +2952,20 @@ func samePostingGroup(a, b *postingGroup) bool {
 		return false
 	}
 
-	if !reflect.DeepEqual(a.addKeys, b.addKeys) || !reflect.DeepEqual(a.removeKeys, b.removeKeys) {
+	if len(a.addKeys) != len(b.addKeys) || len(a.removeKeys) != len(b.removeKeys) {
 		return false
 	}
+	for i, key := range a.addKeys {
+		if key != b.addKeys[i] {
+			return false
+		}
+	}
+
+	for i, key := range a.removeKeys {
+		if key != b.removeKeys[i] {
+			return false
+		}
+	}
 
 	for i := 0; i < len(a.matchers); i++ {
 		if a.matchers[i].String() != b.matchers[i].String() {