perf(approx_topk): Reduce memory usage of HyperLogLog in approx_topk.

pkg/logql/count_min_sketch.go

@@ -3,6 +3,8 @@ package logql
 import (
 	"container/heap"
 	"fmt"
+	"slices"
+	"strings"
 
 	"github.com/axiomhq/hyperloglog"
 	"github.com/cespare/xxhash/v2"
@@ -187,16 +189,17 @@ func NewHeapCountMinSketchVector(ts int64, metricsLength, maxLabels int) HeapCou
 }
 
 func (v *HeapCountMinSketchVector) Add(metric labels.Labels, value float64) {
+	slices.SortFunc(metric, func(a, b labels.Label) int { return strings.Compare(a.Name, b.Name) })
 	v.buffer = metric.Bytes(v.buffer)
 
 	v.F.Add(v.buffer, value)
 
-	// Add our metric if we haven't seen it
-
 	// TODO(karsten): There is a chance that the ids match but not the labels due to hash collision. Ideally there's
 	// an else block the compares the series labels. However, that's not trivial. Besides, instance.Series has the
 	// same issue in its deduping logic.
 	id := xxhash.Sum64(v.buffer)
+
+	// Add our metric if we haven't seen it
 	if _, ok := v.observed[id]; !ok {
 		heap.Push(v, metric)
 		v.observed[id] = struct{}{}

pkg/logql/log/labels.go

@@ -2,7 +2,9 @@ package log
 
 import (
 	"fmt"
+	"slices"
 	"sort"
+	"strings"
 	"sync"
 
 	"github.com/prometheus/prometheus/model/labels"
@@ -585,7 +587,8 @@ func (b *LabelsBuilder) LabelsResult() LabelsResult {
 
 	// Get all labels at once and sort them
 	b.buf = b.UnsortedLabels(b.buf)
-	sort.Sort(b.buf)
+	// sort.Sort(b.buf)
+	slices.SortFunc(b.buf, func(a, b labels.Label) int { return strings.Compare(a.Name, b.Name) })
 	hash := b.hasher.Hash(b.buf)
 
 	if cached, ok := b.resultCache[hash]; ok {

pkg/logql/log/parser_test.go

@@ -241,25 +241,32 @@ func (p *fakeParseHints) ShouldExtract(key string) bool {
 	p.checkCount++
 	return key == p.label || p.extractAll
 }
+
 func (p *fakeParseHints) ShouldExtractPrefix(prefix string) bool {
 	return prefix == p.label || p.extractAll
 }
+
 func (p *fakeParseHints) NoLabels() bool {
 	return false
 }
+
 func (p *fakeParseHints) RecordExtracted(_ string) {
 	p.count++
 }
+
 func (p *fakeParseHints) AllRequiredExtracted() bool {
 	return !p.extractAll && p.count == 1
 }
+
 func (p *fakeParseHints) Reset() {
 	p.checkCount = 0
 	p.count = 0
 }
+
 func (p *fakeParseHints) PreserveError() bool {
 	return false
 }
+
 func (p *fakeParseHints) ShouldContinueParsingLine(_ string, _ *LabelsBuilder) bool {
 	return p.keepGoing
 }
@@ -656,30 +663,36 @@ func Benchmark_Parser(b *testing.B) {
 		b.Run(tt.name, func(b *testing.B) {
 			line := []byte(tt.line)
 			b.Run("no labels hints", func(b *testing.B) {
+				b.ReportAllocs()
 				builder := NewBaseLabelsBuilder().ForLabels(lbs, lbs.Hash())
 				for n := 0; n < b.N; n++ {
 					builder.Reset()
 					_, _ = tt.s.Process(0, line, builder)
+					builder.LabelsResult()
 				}
 			})
 
 			b.Run("labels hints", func(b *testing.B) {
+				b.ReportAllocs()
 				builder := NewBaseLabelsBuilder().ForLabels(lbs, lbs.Hash())
 				builder.parserKeyHints = NewParserHint(tt.LabelParseHints, tt.LabelParseHints, false, false, "", nil)
 
 				for n := 0; n < b.N; n++ {
 					builder.Reset()
 					_, _ = tt.s.Process(0, line, builder)
+					builder.LabelsResult()
 				}
 			})
 
 			b.Run("inline stages", func(b *testing.B) {
+				b.ReportAllocs()
 				stages := []Stage{NewStringLabelFilter(tt.LabelFilterParseHint)}
 				builder := NewBaseLabelsBuilder().ForLabels(lbs, lbs.Hash())
 				builder.parserKeyHints = NewParserHint(nil, nil, false, false, ", nil", stages)
 				for n := 0; n < b.N; n++ {
 					builder.Reset()
 					_, _ = tt.s.Process(0, line, builder)
+					builder.LabelsResult()
 				}
 			})
 		})
@@ -1251,7 +1264,6 @@ func TestXExpressionParserFailures(t *testing.T) {
 		},
 	}
 	for _, tt := range tests {
-
 		t.Run(tt.name, func(t *testing.T) {
 			_, err := NewLogfmtExpressionParser([]LabelExtractionExpr{tt.expression}, false)
 

pkg/logql/sketch/cms.go

@@ -19,7 +19,7 @@ func NewCountMinSketch(w, d uint32) (*CountMinSketch, error) {
 		Depth:       d,
 		Width:       w,
 		Counters:    make2dslice(w, d),
-		HyperLogLog: hyperloglog.New16(),
+		HyperLogLog: hyperloglog.New16NoSparse(),
 	}, nil
 }