don't load stats for point get index usage reporter

Signed-off-by: Yang Keao <[email protected]>

pkg/executor/builder.go

@@ -3571,7 +3571,7 @@ func buildNoRangeTableReader(b *executorBuilder, v *plannercore.PhysicalTableRea
 	e := &TableReaderExecutor{
 		BaseExecutorV2:             exec.NewBaseExecutorV2(b.ctx.GetSessionVars(), v.Schema(), v.ID()),
 		tableReaderExecutorContext: newTableReaderExecutorContext(b.ctx),
-		indexUsageReporter:         b.buildIndexUsageReporter(v),
+		indexUsageReporter:         b.buildIndexUsageReporter(v, true),
 		dagPB:                      dagReq,
 		startTS:                    startTS,
 		txnScope:                   b.txnScope,
@@ -3910,7 +3910,7 @@ func buildNoRangeIndexReader(b *executorBuilder, v *plannercore.PhysicalIndexRea
 	e := &IndexReaderExecutor{
 		indexReaderExecutorContext: newIndexReaderExecutorContext(b.ctx),
 		BaseExecutorV2:             exec.NewBaseExecutorV2(b.ctx.GetSessionVars(), v.Schema(), v.ID()),
-		indexUsageReporter:         b.buildIndexUsageReporter(v),
+		indexUsageReporter:         b.buildIndexUsageReporter(v, true),
 		dagPB:                      dagReq,
 		startTS:                    startTS,
 		txnScope:                   b.txnScope,
@@ -4089,7 +4089,7 @@ func buildNoRangeIndexLookUpReader(b *executorBuilder, v *plannercore.PhysicalIn
 	e := &IndexLookUpExecutor{
 		indexLookUpExecutorContext: newIndexLookUpExecutorContext(b.ctx),
 		BaseExecutorV2:             exec.NewBaseExecutorV2(b.ctx.GetSessionVars(), v.Schema(), v.ID()),
-		indexUsageReporter:         b.buildIndexUsageReporter(v),
+		indexUsageReporter:         b.buildIndexUsageReporter(v, true),
 		dagPB:                      indexReq,
 		startTS:                    startTS,
 		table:                      tbl,
@@ -4240,7 +4240,7 @@ func buildNoRangeIndexMergeReader(b *executorBuilder, v *plannercore.PhysicalInd
 
 	e := &IndexMergeReaderExecutor{
 		BaseExecutor:             exec.NewBaseExecutor(b.ctx, v.Schema(), v.ID()),
-		indexUsageReporter:       b.buildIndexUsageReporter(v),
+		indexUsageReporter:       b.buildIndexUsageReporter(v, true),
 		dagPBs:                   partialReqs,
 		startTS:                  startTS,
 		table:                    tblInfo,
@@ -4272,13 +4272,15 @@ type tableStatsPreloader interface {
 	LoadTableStats(sessionctx.Context)
 }
 
-func buildIndexUsageReporter(ctx sessionctx.Context, plan tableStatsPreloader) (indexUsageReporter *exec.IndexUsageReporter) {
+func buildIndexUsageReporter(ctx sessionctx.Context, plan tableStatsPreloader, loadStats bool) (indexUsageReporter *exec.IndexUsageReporter) {
 	sc := ctx.GetSessionVars().StmtCtx
 	if ctx.GetSessionVars().StmtCtx.IndexUsageCollector != nil &&
 		sc.RuntimeStatsColl != nil {
-		// Preload the table stats. If the statement is a point-get or execute, the planner may not have loaded the
-		// stats.
-		plan.LoadTableStats(ctx)
+		if loadStats {
+			// Preload the table stats. If the statement is a point-get or execute, the planner may not have loaded the
+			// stats.
+			plan.LoadTableStats(ctx)
+		}
 
 		statsMap := sc.GetUsedStatsInfo(false)
 		indexUsageReporter = exec.NewIndexUsageReporter(
@@ -4289,8 +4291,8 @@ func buildIndexUsageReporter(ctx sessionctx.Context, plan tableStatsPreloader) (
 	return indexUsageReporter
 }
 
-func (b *executorBuilder) buildIndexUsageReporter(plan tableStatsPreloader) (indexUsageReporter *exec.IndexUsageReporter) {
-	return buildIndexUsageReporter(b.ctx, plan)
+func (b *executorBuilder) buildIndexUsageReporter(plan tableStatsPreloader, loadStats bool) (indexUsageReporter *exec.IndexUsageReporter) {
+	return buildIndexUsageReporter(b.ctx, plan, loadStats)
 }
 
 func (b *executorBuilder) buildIndexMergeReader(v *plannercore.PhysicalIndexMergeReader) exec.Executor {
@@ -5308,7 +5310,7 @@ func (b *executorBuilder) buildBatchPointGet(plan *plannercore.BatchPointGetPlan
 	decoder := NewRowDecoder(b.ctx, plan.Schema(), plan.TblInfo)
 	e := &BatchPointGetExec{
 		BaseExecutor:       exec.NewBaseExecutor(b.ctx, plan.Schema(), plan.ID()),
-		indexUsageReporter: b.buildIndexUsageReporter(plan),
+		indexUsageReporter: b.buildIndexUsageReporter(plan, true),
 		tblInfo:            plan.TblInfo,
 		idxInfo:            plan.IndexInfo,
 		rowDecoder:         decoder,

pkg/executor/internal/exec/indexusage.go

@@ -15,6 +15,8 @@
 package exec
 
 import (
+	"math"
+
 	"github.com/pingcap/tidb/pkg/meta/model"
 	"github.com/pingcap/tidb/pkg/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/pkg/statistics"
@@ -101,8 +103,10 @@ func (e *IndexUsageReporter) ReportPointGetIndexUsageForHandle(tblInfo *model.Ta
 func (e *IndexUsageReporter) ReportPointGetIndexUsage(tableID int64, physicalTableID int64, indexID int64, kvRequestTotal, rows int64) {
 	tableRowCount, ok := e.getTableRowCount(physicalTableID)
 	if !ok {
-		// skip if the table is empty or the stats is not valid
-		return
+		// it's possible that the point get doesn't have the table stats. In this case, we always
+		// report the tableRowCount as `math.MaxInt32`, so that it'll be recorded in the smallest
+		// non-zero bucket if the rows is greater than 0.
+		tableRowCount = math.MaxInt32
 	}
 
 	sample := indexusage.NewSample(0, uint64(kvRequestTotal), uint64(rows), uint64(tableRowCount))
@@ -111,6 +115,10 @@ func (e *IndexUsageReporter) ReportPointGetIndexUsage(tableID int64, physicalTab
 
 // getTableRowCount returns the `RealtimeCount` of a table
 func (e *IndexUsageReporter) getTableRowCount(tableID int64) (int64, bool) {
+	if e.statsMap == nil {
+		return 0, false
+	}
+
 	stats := e.statsMap.GetUsedInfo(tableID)
 	if stats == nil {
 		return 0, false

pkg/executor/internal/exec/indexusage_test.go

@@ -269,7 +269,8 @@ func TestIndexUsageReporterWithRealData(t *testing.T) {
 			"select * from t where id_1 = 1",
 			"Point_Get",
 			[]indexStatsExpect{
-				{tableID, idx1ID, []indexusage.Sample{indexusage.NewSample(1, 1, 1, 100)}},
+				// The point get will always use smallest bucket.
+				{tableID, idx1ID, []indexusage.Sample{indexusage.NewSample(1, 1, 1, 1000)}},
 			},
 		},
 		{
@@ -519,13 +520,15 @@ func TestIndexUsageReporterWithClusterIndex(t *testing.T) {
 		{
 			"select * from t0 where id = 1",
 			"Point_Get",
-			[]indexStatsExpect{{testTableInfos[0].tableID, testTableInfos[0].pkID, []indexusage.Sample{indexusage.NewSample(1, 1, 1, 100)}}},
+			// The point get will always use smallest bucket.
+			[]indexStatsExpect{{testTableInfos[0].tableID, testTableInfos[0].pkID, []indexusage.Sample{indexusage.NewSample(1, 1, 1, 1000)}}},
 		},
 		// PointGet on CommonHandle
 		{
 			"select * from t1 where id = \"1\"",
 			"Point_Get",
-			[]indexStatsExpect{{testTableInfos[1].tableID, testTableInfos[1].pkID, []indexusage.Sample{indexusage.NewSample(1, 1, 1, 100)}}},
+			// The point get will always use smallest bucket.
+			[]indexStatsExpect{{testTableInfos[1].tableID, testTableInfos[1].pkID, []indexusage.Sample{indexusage.NewSample(1, 1, 1, 1000)}}},
 		},
 		// BatchPointGet on PKAsHandle
 		{

pkg/executor/point_get.go

@@ -73,7 +73,7 @@ func (b *executorBuilder) buildPointGet(p *plannercore.PointGetPlan) exec.Execut
 
 	e := &PointGetExecutor{
 		BaseExecutor:       exec.NewBaseExecutor(b.ctx, p.Schema(), p.ID()),
-		indexUsageReporter: b.buildIndexUsageReporter(p),
+		indexUsageReporter: b.buildIndexUsageReporter(p, false),
 		txnScope:           b.txnScope,
 		readReplicaScope:   b.readReplicaScope,
 		isStaleness:        b.isStaleness,
@@ -204,7 +204,7 @@ func (e *PointGetExecutor) Recreated(p *plannercore.PointGetPlan) {
 	// It's necessary to at least reset the `runtimeStats` of the `BaseExecutor`.
 	// As the `StmtCtx` may have changed, a new index usage reporter should also be created.
 	e.BaseExecutor = exec.NewBaseExecutor(e.Ctx(), p.Schema(), p.ID())
-	e.indexUsageReporter = buildIndexUsageReporter(e.Ctx(), p)
+	e.indexUsageReporter = buildIndexUsageReporter(e.Ctx(), p, false)
 }
 
 // Init set fields needed for PointGetExecutor reuse, this does NOT change baseExecutor field