stats: optimize build topn and histogram

pkg/planner/core/planbuilder.go

@@ -792,7 +792,6 @@ func (b *PlanBuilder) buildDropBindPlan(v *ast.DropBindingStmt) (base.Plan, erro
 	b.visitInfo = appendVisitInfo(b.visitInfo, mysql.SuperPriv, "", "", "", nil)
 	return p, nil
 }
-
 func (b *PlanBuilder) buildSetBindingStatusPlan(v *ast.SetBindingStmt) (base.Plan, error) {
 	var p *SQLBindPlan
 	if v.OriginNode != nil {
@@ -1299,7 +1298,7 @@ func getPossibleAccessPaths(ctx base.PlanContext, tableHints *hint.PlanHints, in
 
 		hasScanHint = true
 
-		// It is syntactically valid to omit index_list for USE INDEX, which means “use no indexes”.
+		// It is syntactically valid to omit index_list for USE INDEX, which means "use no indexes".
 		// Omitting index_list for FORCE INDEX or IGNORE INDEX is a syntax error.
 		// See https://dev.mysql.com/doc/refman/8.0/en/index-hints.html.
 		if !isolationReadEnginesHasTiKV && hint.IndexNames == nil {
@@ -1471,7 +1470,6 @@ func (b *PlanBuilder) buildPrepare(x *ast.PrepareStmt) base.Plan {
 	}
 	return p
 }
-
 func (b *PlanBuilder) buildAdmin(ctx context.Context, as *ast.AdminStmt) (base.Plan, error) {
 	var ret base.Plan
 	var err error
@@ -2253,7 +2251,6 @@ func (b *PlanBuilder) getFullAnalyzeColumnsInfo(
 
 	return nil, nil, nil
 }
-
 func (b *PlanBuilder) getColumnsBasedOnPredicateColumns(
 	tbl *resolve.TableNameW,
 	predicateCols, mustAnalyzedCols *calcOnceMap,
@@ -3041,8 +3038,8 @@ var analyzeOptionDefault = map[ast.AnalyzeOptionType]uint64{
 // TopN reduced from 500 to 100 due to concerns over large number of TopN values collected for customers with many tables.
 // 100 is more inline with other databases. 100-256 is also common for NumBuckets with other databases.
 var analyzeOptionDefaultV2 = map[ast.AnalyzeOptionType]uint64{
-	ast.AnalyzeOptNumBuckets:    256,
-	ast.AnalyzeOptNumTopN:       100,
+	ast.AnalyzeOptNumBuckets:    statistics.DefaultHistogramBuckets,
+	ast.AnalyzeOptNumTopN:       statistics.DefaultTopNValue,
 	ast.AnalyzeOptCMSketchWidth: 2048,
 	ast.AnalyzeOptCMSketchDepth: 5,
 	ast.AnalyzeOptNumSamples:    0,
@@ -3818,7 +3815,6 @@ func (b *PlanBuilder) buildSimple(ctx context.Context, node ast.StmtNode) (base.
 	}
 	return p, nil
 }
-
 func collectVisitInfoFromRevokeStmt(ctx context.Context, sctx base.PlanContext, vi []visitInfo, stmt *ast.RevokeStmt) ([]visitInfo, error) {
 	// To use REVOKE, you must have the GRANT OPTION privilege,
 	// and you must have the privileges that you are granting.
@@ -5205,7 +5201,6 @@ func checkForUserVariables(in ast.Node) error {
 	}
 	return nil
 }
-
 func (b *PlanBuilder) buildDDL(ctx context.Context, node ast.DDLNode) (base.Plan, error) {
 	var authErr error
 	switch v := node.(type) {

pkg/statistics/BUILD.bazel

@@ -10,6 +10,7 @@ go_library(
         "cmsketch.go",
         "cmsketch_util.go",
         "column.go",
+        "constants.go",
         "debugtrace.go",
         "estimate.go",
         "fmsketch.go",
@@ -47,6 +48,7 @@ go_library(
         "//pkg/util/context",
         "//pkg/util/dbterror",
         "//pkg/util/fastrand",
+        "//pkg/util/generic",
         "//pkg/util/hack",
         "//pkg/util/intest",
         "//pkg/util/logutil",
@@ -83,7 +85,7 @@ go_test(
     data = glob(["testdata/**"]),
     embed = [":statistics"],
     flaky = True,
-    shard_count = 42,
+    shard_count = 43,
     deps = [
         "//pkg/config",
         "//pkg/config/kerneltype",