executor, util: wrap cast upon the args for AggFunction

executor/aggfuncs/builder.go

@@ -111,19 +111,17 @@ func buildSum(aggFuncDesc *aggregation.AggFuncDesc, ordinal int) AggFunc {
 	case aggregation.DedupMode:
 		return nil
 	default:
-		switch aggFuncDesc.Args[0].GetType().Tp {
-		case mysql.TypeFloat, mysql.TypeDouble:
-			if aggFuncDesc.HasDistinct {
-				return &sum4DistinctFloat64{base}
-			}
-			return &sum4Float64{base}
-		case mysql.TypeNewDecimal:
+		switch aggFuncDesc.RetTp.EvalType() {
+		case types.ETDecimal:
 			if aggFuncDesc.HasDistinct {
 				return &sum4DistinctDecimal{base}
 			}
 			return &sum4Decimal{base}
 		default:
-			return nil
+			if aggFuncDesc.HasDistinct {
+				return &sum4DistinctFloat64{base}
+			}
+			return &sum4Float64{base}
 		}
 	}
 }
@@ -143,13 +141,13 @@ func buildAvg(aggFuncDesc *aggregation.AggFuncDesc, ordinal int) AggFunc {
 	// Build avg functions which consume the original data and update their
 	// partial results.
 	case aggregation.CompleteMode, aggregation.Partial1Mode:
-		switch aggFuncDesc.Args[0].GetType().Tp {
-		case mysql.TypeNewDecimal:
+		switch aggFuncDesc.RetTp.EvalType() {
+		case types.ETDecimal:
 			if aggFuncDesc.HasDistinct {
 				return &avgOriginal4DistinctDecimal{base}
 			}
 			return &avgOriginal4Decimal{baseAvgDecimal{base}}
-		case mysql.TypeFloat, mysql.TypeDouble:
+		default:
 			if aggFuncDesc.HasDistinct {
 				return &avgOriginal4DistinctFloat64{base}
 			}
@@ -249,14 +247,6 @@ func buildMaxMin(aggFuncDesc *aggregation.AggFuncDesc, ordinal int, isMax bool)
 
 // buildGroupConcat builds the AggFunc implementation for function "GROUP_CONCAT".
 func buildGroupConcat(ctx sessionctx.Context, aggFuncDesc *aggregation.AggFuncDesc, ordinal int) AggFunc {
-	// TODO: There might be different kind of types of the args,
-	// we should add CastAsString upon every arg after cast can be pushed down to coprocessor.
-	// And this check can be removed at that time.
-	for _, arg := range aggFuncDesc.Args {
-		if arg.GetType().EvalType() != types.ETString {
-			return nil
-		}
-	}
 	switch aggFuncDesc.Mode {
 	case aggregation.DedupMode:
 		return nil
@@ -291,39 +281,27 @@ func buildGroupConcat(ctx sessionctx.Context, aggFuncDesc *aggregation.AggFuncDe
 
 // buildBitOr builds the AggFunc implementation for function "BIT_OR".
 func buildBitOr(aggFuncDesc *aggregation.AggFuncDesc, ordinal int) AggFunc {
-	switch aggFuncDesc.Args[0].GetType().EvalType() {
-	case types.ETInt:
-		base := baseAggFunc{
-			args:    aggFuncDesc.Args,
-			ordinal: ordinal,
-		}
-		return &bitOrUint64{baseBitAggFunc{base}}
+	base := baseAggFunc{
+		args:    aggFuncDesc.Args,
+		ordinal: ordinal,
 	}
-	return nil
+	return &bitOrUint64{baseBitAggFunc{base}}
 }
 
 // buildBitXor builds the AggFunc implementation for function "BIT_XOR".
 func buildBitXor(aggFuncDesc *aggregation.AggFuncDesc, ordinal int) AggFunc {
-	switch aggFuncDesc.Args[0].GetType().EvalType() {
-	case types.ETInt:
-		base := baseAggFunc{
-			args:    aggFuncDesc.Args,
-			ordinal: ordinal,
-		}
-		return &bitXorUint64{baseBitAggFunc{base}}
+	base := baseAggFunc{
+		args:    aggFuncDesc.Args,
+		ordinal: ordinal,
 	}
-	return nil
+	return &bitXorUint64{baseBitAggFunc{base}}
 }
 
 // buildBitAnd builds the AggFunc implementation for function "BIT_AND".
 func buildBitAnd(aggFuncDesc *aggregation.AggFuncDesc, ordinal int) AggFunc {
-	switch aggFuncDesc.Args[0].GetType().EvalType() {
-	case types.ETInt:
-		base := baseAggFunc{
-			args:    aggFuncDesc.Args,
-			ordinal: ordinal,
-		}
-		return &bitAndUint64{baseBitAggFunc{base}}
+	base := baseAggFunc{
+		args:    aggFuncDesc.Args,
+		ordinal: ordinal,
 	}
-	return nil
+	return &bitAndUint64{baseBitAggFunc{base}}
 }

executor/builder.go

@@ -825,11 +825,43 @@ func (b *executorBuilder) buildHashJoin(v *plan.PhysicalHashJoin) Executor {
 	return e
 }
 
+// wrapCastForAggArgs wraps the args of an aggregate function with a cast function.
+func (b *executorBuilder) wrapCastForAggArgs(funcs []*aggregation.AggFuncDesc) {
+	for _, f := range funcs {
+		// We do not need to wrap cast upon these functions,
+		// since the EvalXXX method called by the arg is determined by the corresponding arg type.
+		if f.Name == ast.AggFuncCount || f.Name == ast.AggFuncMin || f.Name == ast.AggFuncMax || f.Name == ast.AggFuncFirstRow {
+			continue
+		}
+		var castFunc func(ctx sessionctx.Context, expr expression.Expression) expression.Expression
+		switch retTp := f.RetTp; retTp.EvalType() {
+		case types.ETInt:
+			castFunc = expression.WrapWithCastAsInt
+		case types.ETReal:
+			castFunc = expression.WrapWithCastAsReal
+		case types.ETString:
+			castFunc = expression.WrapWithCastAsString
+		case types.ETDecimal:
+			castFunc = expression.WrapWithCastAsDecimal
+		default:
+			panic("should never happen in executorBuilder.wrapCastForAggArgs")
+		}
+		for i := range f.Args {
+			f.Args[i] = castFunc(b.ctx, f.Args[i])
+		}
+	}
+}
+
 // buildProjBelowAgg builds a ProjectionExec below AggregationExec.
 // If all the args of `aggFuncs`, and all the item of `groupByItems`
 // are columns or constants, we do not need to build the `proj`.
 func (b *executorBuilder) buildProjBelowAgg(aggFuncs []*aggregation.AggFuncDesc, groupByItems []expression.Expression, src Executor) Executor {
 	hasScalarFunc := false
+	// If the mode is FinalMode, we do not need to wrap cast upon the args,
+	// since the types of the args are already the expected.
+	if len(aggFuncs) > 0 && aggFuncs[0].Mode != aggregation.FinalMode {
+		b.wrapCastForAggArgs(aggFuncs)
+	}
 	for i := 0; !hasScalarFunc && i < len(aggFuncs); i++ {
 		f := aggFuncs[i]
 		for _, arg := range f.Args {

util/chunk/row.go

@@ -189,7 +189,15 @@ func (r Row) GetDatum(colIdx int, tp *types.FieldType) types.Datum {
 		if !r.IsNull(colIdx) {
 			d.SetMysqlDecimal(r.GetMyDecimal(colIdx))
 			d.SetLength(tp.Flen)
-			d.SetFrac(tp.Decimal)
+			// If tp.Decimal is unspecified(-1), we should set it to the real
+			// fraction length of the decimal value, if not, the d.Frac will
+			// be set to MAX_UINT16 which will cause unexpected BadNumber error
+			// when encoding.
+			if tp.Decimal == types.UnspecifiedLength {
+				d.SetFrac(d.Frac())
+			} else {
+				d.SetFrac(tp.Decimal)
+			}
 		}
 	case mysql.TypeEnum:
 		if !r.IsNull(colIdx) {