statistics: use analyze NDV rate proto

Author: 0xPoe

pkg/executor/builder.go

@@ -3169,6 +3169,7 @@ func (b *executorBuilder) buildAnalyzeSamplingPushdown(
 		modifyCount = int64(val.(int))
 	})
 	sampleRate := new(float64)
+	ndvRate := statistics.DefaultNDVSampleRate
 	var sampleRateReason string
 	if opts[ast.AnalyzeOptNumSamples] == 0 {
 		*sampleRate = math.Float64frombits(opts[ast.AnalyzeOptSampleRate])
@@ -3229,6 +3230,7 @@ func (b *executorBuilder) buildAnalyzeSamplingPushdown(
 		BucketSize:   int64(opts[ast.AnalyzeOptNumBuckets]),
 		SampleSize:   int64(opts[ast.AnalyzeOptNumSamples]),
 		SampleRate:   sampleRate,
+		NdvRate:      &ndvRate,
 		SketchSize:   statistics.MaxSketchSize,
 		ColumnsInfo:  util.ColumnsToProto(task.ColsInfo, task.TblInfo.PKIsHandle, false, false),
 		ColumnGroups: colGroups,

pkg/statistics/row_sampler.go

@@ -160,9 +160,9 @@ type ReservoirRowSampleItem struct {
 // EmptyReservoirSampleItemSize = (24 + 16 + 8) now.
 const EmptyReservoirSampleItemSize = int64(unsafe.Sizeof(ReservoirRowSampleItem{}))
 
-// sketchSampleRate applies after a collector has gathered MaxFMSketchSize sketch rows.
+// DefaultNDVSampleRate applies after a collector has gathered MaxFMSketchSize sketch rows.
 // The warm-up keeps small-table NDV behavior exact while bounding extra sketch work for large scans.
-const sketchSampleRate = 0.01
+const DefaultNDVSampleRate = 0.01
 
 // MemUsage returns the memory usage of sample item.
 func (i ReservoirRowSampleItem) MemUsage() (sum int64) {
@@ -218,6 +218,7 @@ type RowSampleBuilder struct {
 	ColGroups       [][]int64
 	MaxSampleSize   int
 	SampleRate      float64
+	NDVSampleRate   float64
 	MaxFMSketchSize int
 }
 
@@ -261,6 +262,11 @@ func (s *RowSampleBuilder) Collect() (RowSampleCollector, error) {
 	if minSketchSampleCount <= 0 {
 		minSketchSampleCount = MaxSketchSize
 	}
+	ndvSampleRate := s.NDVSampleRate
+	if ndvSampleRate <= 0 {
+		ndvSampleRate = DefaultNDVSampleRate
+	}
+	ndvSampleRate = min(ndvSampleRate, 1)
 	ctx := context.TODO()
 	chk := s.RecordSet.NewChunk(nil)
 	it := chunk.NewIterator4Chunk(chk)
@@ -300,7 +306,7 @@ func (s *RowSampleBuilder) Collect() (RowSampleCollector, error) {
 					datums[i].SetBytes(encodedKey)
 				}
 			}
-			collectSketch := collector.Base().SketchSampleCount < int64(minSketchSampleCount) || s.Rng.Float64() < sketchSampleRate
+			collectSketch := collector.Base().SketchSampleCount < int64(minSketchSampleCount) || s.Rng.Float64() < ndvSampleRate
 			err := collector.Base().collectColumns(s.Sc, datums, sizes, collectSketch)
 			if err != nil {
 				return nil, err

pkg/store/mockstore/unistore/cophandler/analyze.go

@@ -457,6 +457,7 @@ func handleAnalyzeFullSamplingReq(
 		MaxSampleSize:   int(colReq.SampleSize),
 		MaxFMSketchSize: int(colReq.SketchSize),
 		SampleRate:      colReq.GetSampleRate(),
+		NDVSampleRate:   colReq.GetNdvRate(),
 		Rng:             rand.New(rand.NewSource(time.Now().UnixNano())),
 	}
 	collector, err := builder.Collect()