*: replace compareDatum by compare

executor/aggfuncs/func_group_concat.go

@@ -293,6 +293,7 @@ type topNRows struct {
 	// ('---', 'ccc') should be poped from heap, so '-' should be appended to result.
 	// eg: 'aaa---bbb---ccc' -> 'aaa---bbb-'
 	isSepTruncated bool
+	collators      []collate.Collator
 }
 
 func (h topNRows) Len() int {
@@ -302,7 +303,7 @@ func (h topNRows) Len() int {
 func (h topNRows) Less(i, j int) bool {
 	n := len(h.rows[i].byItems)
 	for k := 0; k < n; k++ {
-		ret, err := h.rows[i].byItems[k].CompareDatum(h.sctx.GetSessionVars().StmtCtx, h.rows[j].byItems[k])
+		ret, err := h.rows[i].byItems[k].Compare(h.sctx.GetSessionVars().StmtCtx, h.rows[j].byItems[k], h.collators[k])
 		if err != nil {
 			h.err = err
 			return false
@@ -411,8 +412,10 @@ func (e *groupConcatOrder) AppendFinalResult2Chunk(sctx sessionctx.Context, pr P
 
 func (e *groupConcatOrder) AllocPartialResult() (pr PartialResult, memDelta int64) {
 	desc := make([]bool, len(e.byItems))
+	ctors := make([]collate.Collator, 0, len(e.byItems))
 	for i, byItem := range e.byItems {
 		desc[i] = byItem.Desc
+		ctors = append(ctors, collate.GetCollator(byItem.Expr.GetType().Collate))
 	}
 	p := &partialResult4GroupConcatOrder{
 		topN: &topNRows{
@@ -421,6 +424,7 @@ func (e *groupConcatOrder) AllocPartialResult() (pr PartialResult, memDelta int6
 			limitSize:      e.maxLen,
 			sepSize:        uint64(len(e.sep)),
 			isSepTruncated: false,
+			collators:      ctors,
 		},
 	}
 	return PartialResult(p), DefPartialResult4GroupConcatOrderSize + DefTopNRowsSize
@@ -513,8 +517,10 @@ func (e *groupConcatDistinctOrder) AppendFinalResult2Chunk(sctx sessionctx.Conte
 
 func (e *groupConcatDistinctOrder) AllocPartialResult() (pr PartialResult, memDelta int64) {
 	desc := make([]bool, len(e.byItems))
+	ctors := make([]collate.Collator, 0, len(e.byItems))
 	for i, byItem := range e.byItems {
 		desc[i] = byItem.Desc
+		ctors = append(ctors, collate.GetCollator(byItem.Expr.GetType().Collate))
 	}
 	valSet, setSize := set.NewStringSetWithMemoryUsage()
 	p := &partialResult4GroupConcatOrderDistinct{
@@ -524,6 +530,7 @@ func (e *groupConcatDistinctOrder) AllocPartialResult() (pr PartialResult, memDe
 			limitSize:      e.maxLen,
 			sepSize:        uint64(len(e.sep)),
 			isSepTruncated: false,
+			collators:      ctors,
 		},
 		valSet: valSet,
 	}

executor/builder.go

@@ -55,6 +55,7 @@ import (
 	"github.com/pingcap/tidb/util"
 	"github.com/pingcap/tidb/util/admin"
 	"github.com/pingcap/tidb/util/chunk"
+	"github.com/pingcap/tidb/util/collate"
 	"github.com/pingcap/tidb/util/cteutil"
 	"github.com/pingcap/tidb/util/execdetails"
 	"github.com/pingcap/tidb/util/logutil"
@@ -1059,6 +1060,11 @@ func (b *executorBuilder) buildUnionScanFromReader(reader Executor, v *plannerco
 		reader = sel.children[0]
 	}
 
+	us.collators = make([]collate.Collator, 0, len(us.columns))
+	for _, tp := range retTypes(us) {
+		us.collators = append(us.collators, collate.GetCollator(tp.Collate))
+	}
+
 	switch x := reader.(type) {
 	case *TableReaderExecutor:
 		us.desc = x.desc

executor/union_scan.go

@@ -28,6 +28,7 @@ import (
 	"github.com/pingcap/tidb/tablecodec"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/chunk"
+	"github.com/pingcap/tidb/util/collate"
 )
 
 // UnionScanExec merges the rows from dirty table and the rows from distsql request.
@@ -59,6 +60,7 @@ type UnionScanExec struct {
 
 	// cacheTable not nil means it's reading from cached table.
 	cacheTable kv.MemBuffer
+	collators  []collate.Collator
 }
 
 // Open implements the Executor Open interface.
@@ -273,13 +275,13 @@ func (us *UnionScanExec) compare(a, b []types.Datum) (int, error) {
 	for _, colOff := range us.usedIndex {
 		aColumn := a[colOff]
 		bColumn := b[colOff]
-		cmp, err := aColumn.CompareDatum(sc, &bColumn)
+		cmp, err := aColumn.Compare(sc, &bColumn, us.collators[colOff])
 		if err != nil {
 			return 0, err
 		}
 		if cmp != 0 {
 			return cmp, nil
 		}
 	}
-	return us.belowHandleCols.Compare(a, b)
+	return us.belowHandleCols.Compare(a, b, us.collators)
 }

expression/aggregation/aggregation.go

@@ -26,6 +26,7 @@ import (
 	"github.com/pingcap/tidb/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/chunk"
+	"github.com/pingcap/tidb/util/collate"
 	"github.com/pingcap/tipb/go-tipb"
 )
 
@@ -68,9 +69,9 @@ func NewDistAggFunc(expr *tipb.Expr, fieldTps []*types.FieldType, sc *stmtctx.St
 	case tipb.ExprType_GroupConcat:
 		return &concatFunction{aggFunction: newAggFunc(ast.AggFuncGroupConcat, args, false)}, nil
 	case tipb.ExprType_Max:
-		return &maxMinFunction{aggFunction: newAggFunc(ast.AggFuncMax, args, false), isMax: true}, nil
+		return &maxMinFunction{aggFunction: newAggFunc(ast.AggFuncMax, args, false), isMax: true, ctor: collate.GetCollator(args[0].GetType().Collate)}, nil
 	case tipb.ExprType_Min:
-		return &maxMinFunction{aggFunction: newAggFunc(ast.AggFuncMin, args, false)}, nil
+		return &maxMinFunction{aggFunction: newAggFunc(ast.AggFuncMin, args, false), ctor: collate.GetCollator(args[0].GetType().Collate)}, nil
 	case tipb.ExprType_First:
 		return &firstRowFunction{aggFunction: newAggFunc(ast.AggFuncFirstRow, args, false)}, nil
 	case tipb.ExprType_Agg_BitOr:

expression/aggregation/descriptor.go

@@ -28,6 +28,7 @@ import (
 	"github.com/pingcap/tidb/sessionctx"
 	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/types"
+	"github.com/pingcap/tidb/util/collate"
 )
 
 // AggFuncDesc describes an aggregation function signature, only used in planner.
@@ -230,9 +231,9 @@ func (a *AggFuncDesc) GetAggFunc(ctx sessionctx.Context) Aggregation {
 		}
 		return &concatFunction{aggFunction: aggFunc, maxLen: maxLen}
 	case ast.AggFuncMax:
-		return &maxMinFunction{aggFunction: aggFunc, isMax: true}
+		return &maxMinFunction{aggFunction: aggFunc, isMax: true, ctor: collate.GetCollator(a.Args[0].GetType().Collate)}
 	case ast.AggFuncMin:
-		return &maxMinFunction{aggFunction: aggFunc, isMax: false}
+		return &maxMinFunction{aggFunction: aggFunc, isMax: false, ctor: collate.GetCollator(a.Args[0].GetType().Collate)}
 	case ast.AggFuncFirstRow:
 		return &firstRowFunction{aggFunction: aggFunc}
 	case ast.AggFuncBitOr:

expression/aggregation/max_min.go

@@ -18,11 +18,13 @@ import (
 	"github.com/pingcap/tidb/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/chunk"
+	"github.com/pingcap/tidb/util/collate"
 )
 
 type maxMinFunction struct {
 	aggFunction
 	isMax bool
+	ctor  collate.Collator
 }
 
 // GetResult implements Aggregation interface.
@@ -49,7 +51,7 @@ func (mmf *maxMinFunction) Update(evalCtx *AggEvaluateContext, sc *stmtctx.State
 		return nil
 	}
 	var c int
-	c, err = evalCtx.Value.CompareDatum(sc, &value)
+	c, err = evalCtx.Value.Compare(sc, &value, mmf.ctor)
 	if err != nil {
 		return err
 	}

planner/core/handle_cols.go

@@ -26,6 +26,7 @@ import (
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/chunk"
 	"github.com/pingcap/tidb/util/codec"
+	"github.com/pingcap/tidb/util/collate"
 )
 
 // HandleCols is the interface that holds handle columns.
@@ -48,7 +49,7 @@ type HandleCols interface {
 	// NumCols returns the number of columns.
 	NumCols() int
 	// Compare compares two datum rows by handle order.
-	Compare(a, b []types.Datum) (int, error)
+	Compare(a, b []types.Datum, ctors []collate.Collator) (int, error)
 	// GetFieldTypes return field types of columns.
 	GetFieldsTypes() []*types.FieldType
 }
@@ -145,11 +146,11 @@ func (cb *CommonHandleCols) String() string {
 }
 
 // Compare implements the kv.HandleCols interface.
-func (cb *CommonHandleCols) Compare(a, b []types.Datum) (int, error) {
-	for _, col := range cb.columns {
+func (cb *CommonHandleCols) Compare(a, b []types.Datum, ctors []collate.Collator) (int, error) {
+	for i, col := range cb.columns {
 		aDatum := &a[col.Index]
 		bDatum := &b[col.Index]
-		cmp, err := aDatum.CompareDatum(cb.sc, bDatum)
+		cmp, err := aDatum.Compare(cb.sc, bDatum, ctors[i])
 		if err != nil {
 			return 0, err
 		}
@@ -237,7 +238,7 @@ func (ib *IntHandleCols) NumCols() int {
 }
 
 // Compare implements the kv.HandleCols interface.
-func (ib *IntHandleCols) Compare(a, b []types.Datum) (int, error) {
+func (ib *IntHandleCols) Compare(a, b []types.Datum, ctors []collate.Collator) (int, error) {
 	aInt := a[ib.col.Index].GetInt64()
 	bInt := b[ib.col.Index].GetInt64()
 	if aInt == bInt {

util/ranger/detacher.go

@@ -448,7 +448,8 @@ func allSinglePoints(sc *stmtctx.StatementContext, points []*point) []*point {
 		if !left.start || right.start || left.excl || right.excl {
 			return nil
 		}
-		cmp, err := left.value.CompareDatum(sc, &right.value)
+		// Since the point's collations are equal to the column's collation, we can use any of them.
+		cmp, err := left.value.Compare(sc, &right.value, collate.GetCollator(left.value.Collation()))
 		if err != nil || cmp != 0 {
 			return nil
 		}

util/ranger/points.go

@@ -467,7 +467,7 @@ func handleEnumFromBinOp(sc *stmtctx.StatementContext, ft *types.FieldType, val
 		}
 
 		d := types.NewCollateMysqlEnumDatum(tmpEnum, ft.Collate)
-		if v, err := d.CompareDatum(sc, &val); err == nil {
+		if v, err := d.Compare(sc, &val, collate.GetCollator(ft.Collate)); err == nil {
 			switch op {
 			case ast.LT:
 				if v < 0 {