statistics: reduce allocation of types.Context (#52615) (#52963)

close #52342

pkg/statistics/BUILD.bazel

@@ -41,6 +41,7 @@ go_library(
         "//pkg/util/chunk",
         "//pkg/util/codec",
         "//pkg/util/collate",
+        "//pkg/util/context",
         "//pkg/util/dbterror",
         "//pkg/util/fastrand",
         "//pkg/util/hack",

pkg/statistics/handle/BUILD.bazel

@@ -16,7 +16,6 @@ go_library(
         "//pkg/parser/mysql",
         "//pkg/parser/terror",
         "//pkg/sessionctx",
-        "//pkg/sessionctx/stmtctx",
         "//pkg/sessionctx/sysproctrack",
         "//pkg/statistics",
         "//pkg/statistics/handle/autoanalyze",

pkg/statistics/handle/bootstrap.go

@@ -18,7 +18,6 @@ import (
 	"context"
 	"sync"
 	"sync/atomic"
-	"time"
 
 	"github.com/pingcap/errors"
 	"github.com/pingcap/tidb/pkg/config"
@@ -28,7 +27,6 @@ import (
 	"github.com/pingcap/tidb/pkg/parser/mysql"
 	"github.com/pingcap/tidb/pkg/parser/terror"
 	"github.com/pingcap/tidb/pkg/sessionctx"
-	"github.com/pingcap/tidb/pkg/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/pkg/statistics"
 	"github.com/pingcap/tidb/pkg/statistics/handle/cache"
 	"github.com/pingcap/tidb/pkg/statistics/handle/initstats"
@@ -558,19 +556,15 @@ func (*Handle) initStatsBuckets4Chunk(cache statstypes.StatsCache, iter *chunk.I
 			}
 			hist = &column.Histogram
 			d := types.NewBytesDatum(row.GetBytes(5))
-			// Setting TimeZone to time.UTC aligns with HistogramFromStorage and can fix #41938. However, #41985 still exist.
-			// TODO: do the correct time zone conversion for timestamp-type columns' upper/lower bounds.
-			sc := stmtctx.NewStmtCtxWithTimeZone(time.UTC)
-			sc.SetTypeFlags(sc.TypeFlags().WithIgnoreInvalidDateErr(true).WithIgnoreZeroInDate(true))
 			var err error
-			lower, err = d.ConvertTo(sc.TypeCtx(), &column.Info.FieldType)
+			lower, err = d.ConvertTo(statistics.UTCWithAllowInvalidDateCtx, &column.Info.FieldType)
 			if err != nil {
 				logutil.BgLogger().Debug("decode bucket lower bound failed", zap.Error(err))
 				delete(table.Columns, histID)
 				continue
 			}
 			d = types.NewBytesDatum(row.GetBytes(6))
-			upper, err = d.ConvertTo(sc.TypeCtx(), &column.Info.FieldType)
+			upper, err = d.ConvertTo(statistics.UTCWithAllowInvalidDateCtx, &column.Info.FieldType)
 			if err != nil {
 				logutil.BgLogger().Debug("decode bucket upper bound failed", zap.Error(err))
 				delete(table.Columns, histID)

pkg/statistics/handle/storage/BUILD.bazel

@@ -20,7 +20,6 @@ go_library(
         "//pkg/parser/mysql",
         "//pkg/parser/terror",
         "//pkg/sessionctx",
-        "//pkg/sessionctx/stmtctx",
         "//pkg/sessionctx/variable",
         "//pkg/statistics",
         "//pkg/statistics/handle/cache",

pkg/statistics/handle/storage/json.go

@@ -18,14 +18,12 @@ import (
 	"bytes"
 	"encoding/json"
 	"io"
-	"time"
 
 	"github.com/klauspost/compress/gzip"
 	"github.com/pingcap/errors"
 	"github.com/pingcap/tidb/pkg/parser/model"
 	"github.com/pingcap/tidb/pkg/parser/mysql"
 	"github.com/pingcap/tidb/pkg/sessionctx"
-	"github.com/pingcap/tidb/pkg/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/pkg/statistics"
 	"github.com/pingcap/tidb/pkg/statistics/handle/util"
 	"github.com/pingcap/tidb/pkg/types"
@@ -103,8 +101,7 @@ func GenJSONTableFromStats(sctx sessionctx.Context, dbName string, tableInfo *mo
 		Version:      tbl.Version,
 	}
 	for _, col := range tbl.Columns {
-		sc := stmtctx.NewStmtCtxWithTimeZone(time.UTC)
-		hist, err := col.ConvertTo(sc, types.NewFieldType(mysql.TypeBlob))
+		hist, err := col.ConvertTo(statistics.UTCWithAllowInvalidDateCtx, types.NewFieldType(mysql.TypeBlob))
 		if err != nil {
 			return nil, errors.Trace(err)
 		}
@@ -183,7 +180,6 @@ func TableStatsFromJSON(tableInfo *model.TableInfo, physicalID int64, jsonTbl *u
 				continue
 			}
 			hist := statistics.HistogramFromProto(jsonCol.Histogram)
-			sc := stmtctx.NewStmtCtxWithTimeZone(time.UTC)
 			tmpFT := colInfo.FieldType
 			// For new collation data, when storing the bounds of the histogram, we store the collate key instead of the
 			// original value.
@@ -195,7 +191,7 @@ func TableStatsFromJSON(tableInfo *model.TableInfo, physicalID int64, jsonTbl *u
 			if colInfo.FieldType.EvalType() == types.ETString && colInfo.FieldType.GetType() != mysql.TypeEnum && colInfo.FieldType.GetType() != mysql.TypeSet {
 				tmpFT = *types.NewFieldType(mysql.TypeBlob)
 			}
-			hist, err := hist.ConvertTo(sc, &tmpFT)
+			hist, err := hist.ConvertTo(statistics.UTCWithAllowInvalidDateCtx, &tmpFT)
 			if err != nil {
 				return nil, errors.Trace(err)
 			}

pkg/statistics/handle/storage/read.go

@@ -26,7 +26,6 @@ import (
 	"github.com/pingcap/tidb/pkg/parser/model"
 	"github.com/pingcap/tidb/pkg/parser/mysql"
 	"github.com/pingcap/tidb/pkg/sessionctx"
-	"github.com/pingcap/tidb/pkg/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/pkg/statistics"
 	statslogutil "github.com/pingcap/tidb/pkg/statistics/handle/logutil"
 	statstypes "github.com/pingcap/tidb/pkg/statistics/handle/types"
@@ -99,10 +98,6 @@ func HistogramFromStorage(sctx sessionctx.Context, tableID int64, colID int64, t
 			lowerBound = rows[i].GetDatum(2, &fields[2].Column.FieldType)
 			upperBound = rows[i].GetDatum(3, &fields[3].Column.FieldType)
 		} else {
-			// Invalid date values may be inserted into table under some relaxed sql mode. Those values may exist in statistics.
-			// Hence, when reading statistics, we should skip invalid date check. See #39336.
-			sc := stmtctx.NewStmtCtxWithTimeZone(time.UTC)
-			sc.SetTypeFlags(sc.TypeFlags().WithIgnoreInvalidDateErr(true).WithIgnoreZeroInDate(true))
 			d := rows[i].GetDatum(2, &fields[2].Column.FieldType)
 			// For new collation data, when storing the bounds of the histogram, we store the collate key instead of the
 			// original value.
@@ -114,12 +109,12 @@ func HistogramFromStorage(sctx sessionctx.Context, tableID int64, colID int64, t
 			if tp.EvalType() == types.ETString && tp.GetType() != mysql.TypeEnum && tp.GetType() != mysql.TypeSet {
 				tp = types.NewFieldType(mysql.TypeBlob)
 			}
-			lowerBound, err = d.ConvertTo(sc.TypeCtx(), tp)
+			lowerBound, err = d.ConvertTo(statistics.UTCWithAllowInvalidDateCtx, tp)
 			if err != nil {
 				return nil, errors.Trace(err)
 			}
 			d = rows[i].GetDatum(3, &fields[3].Column.FieldType)
-			upperBound, err = d.ConvertTo(sc.TypeCtx(), tp)
+			upperBound, err = d.ConvertTo(statistics.UTCWithAllowInvalidDateCtx, tp)
 			if err != nil {
 				return nil, errors.Trace(err)
 			}

pkg/statistics/histogram.go

@@ -200,13 +200,13 @@ func (hg *Histogram) DecodeTo(tp *types.FieldType, timeZone *time.Location) erro
 }
 
 // ConvertTo converts the histogram bucket values into `tp`.
-func (hg *Histogram) ConvertTo(sc *stmtctx.StatementContext, tp *types.FieldType) (*Histogram, error) {
+func (hg *Histogram) ConvertTo(tctx types.Context, tp *types.FieldType) (*Histogram, error) {
 	hist := NewHistogram(hg.ID, hg.NDV, hg.NullCount, hg.LastUpdateVersion, tp, hg.Len(), hg.TotColSize)
 	hist.Correlation = hg.Correlation
 	iter := chunk.NewIterator4Chunk(hg.Bounds)
 	for row := iter.Begin(); row != iter.End(); row = iter.Next() {
 		d := row.GetDatum(0, hg.Tp)
-		d, err := d.ConvertTo(sc.TypeCtx(), tp)
+		d, err := d.ConvertTo(tctx, tp)
 		if err != nil {
 			return nil, errors.Trace(err)
 		}

pkg/statistics/scalar.go

@@ -20,8 +20,8 @@ import (
 	"time"
 
 	"github.com/pingcap/tidb/pkg/parser/mysql"
-	"github.com/pingcap/tidb/pkg/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/pkg/types"
+	"github.com/pingcap/tidb/pkg/util/context"
 )
 
 // calcFraction is used to calculate the fraction of the interval [lower, upper] that lies within the [lower, value]
@@ -43,6 +43,12 @@ func calcFraction(lower, upper, value float64) float64 {
 	return frac
 }
 
+// UTCWithAllowInvalidDateCtx is introduced for the following reason:
+//
+//	Invalid date values may be inserted into table under some relaxed sql mode. Those values may exist in statistics.
+//	Hence, when reading statistics, we should skip invalid date check. See #39336.
+var UTCWithAllowInvalidDateCtx = types.NewContext(types.DefaultStmtFlags|types.FlagIgnoreInvalidDateErr|types.FlagIgnoreZeroInDateErr, time.UTC, context.IgnoreWarn)
+
 func convertDatumToScalar(value *types.Datum, commonPfxLen int) float64 {
 	switch value.Kind() {
 	case types.KindFloat32:
@@ -72,8 +78,7 @@ func convertDatumToScalar(value *types.Datum, commonPfxLen int) float64 {
 		case mysql.TypeTimestamp:
 			minTime = types.MinTimestamp
 		}
-		sc := stmtctx.NewStmtCtxWithTimeZone(types.BoundTimezone)
-		return float64(valueTime.Sub(sc.TypeCtx(), &minTime).Duration)
+		return float64(valueTime.Sub(UTCWithAllowInvalidDateCtx, &minTime).Duration)
 	case types.KindString, types.KindBytes:
 		bytes := value.GetBytes()
 		if len(bytes) <= commonPfxLen {