planner: the precision of a decimal type should not be more than MaxD…

…ecimalWidth (#21046)
pingcap · Nov 13, 2020 · b6b4c67 · b6b4c67
1 parent d084651
commit b6b4c67
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Showing 2 changed files with 4 additions and 2 deletions.
diff --git a/expression/aggregation/base_func.go b/expression/aggregation/base_func.go
@@ -183,13 +183,13 @@ func (a *baseFuncDesc) typeInfer4Sum(ctx sessionctx.Context) {
 	case mysql.TypeTiny, mysql.TypeShort, mysql.TypeInt24, mysql.TypeLong, mysql.TypeLonglong, mysql.TypeYear:
 		a.RetTp = types.NewFieldType(mysql.TypeNewDecimal)
 		a.RetTp.Flen, a.RetTp.Decimal = utils.MinInt(a.Args[0].GetType().Flen+21, mysql.MaxDecimalWidth), 0
-		if a.Args[0].GetType().Flen < 0 {
+		if a.Args[0].GetType().Flen < 0 || a.RetTp.Flen > mysql.MaxDecimalWidth {
 			a.RetTp.Flen = mysql.MaxDecimalWidth
 		}
 	case mysql.TypeNewDecimal:
 		a.RetTp = types.NewFieldType(mysql.TypeNewDecimal)
 		a.RetTp.Flen, a.RetTp.Decimal = utils.MinInt(a.Args[0].GetType().Flen+22), a.Args[0].GetType().Decimal
-		if a.Args[0].GetType().Flen < 0 {
+		if a.Args[0].GetType().Flen < 0 || a.RetTp.Flen > mysql.MaxDecimalWidth {
 			a.RetTp.Flen = mysql.MaxDecimalWidth
 		}
 		if a.RetTp.Decimal < 0 || a.RetTp.Decimal > mysql.MaxDecimalScale {

diff --git a/expression/typeinfer_test.go b/expression/typeinfer_test.go
@@ -824,13 +824,15 @@ func (s *testInferTypeSuite) createTestCase4Aggregations() []typeInferTestCase {
 		{"sum(c_float_d)", mysql.TypeDouble, charset.CharsetBin, mysql.BinaryFlag, mysql.MaxRealWidth, types.UnspecifiedLength},
 		{"sum(c_double_d)", mysql.TypeDouble, charset.CharsetBin, mysql.BinaryFlag, mysql.MaxRealWidth, types.UnspecifiedLength},
 		{"sum(c_decimal)", mysql.TypeNewDecimal, charset.CharsetBin, mysql.BinaryFlag, 28, 3},
+		{"sum(cast(c_decimal as decimal(65,3)))", mysql.TypeNewDecimal, charset.CharsetBin, mysql.BinaryFlag, 65, 3},
 		{"sum(1.0)", mysql.TypeNewDecimal, charset.CharsetBin, mysql.BinaryFlag, 25, 1},
 		{"sum(1.2e2)", mysql.TypeDouble, charset.CharsetBin, mysql.BinaryFlag, mysql.MaxRealWidth, types.UnspecifiedLength},
 		{"sum(c_char)", mysql.TypeDouble, charset.CharsetBin, mysql.BinaryFlag, mysql.MaxRealWidth, types.UnspecifiedLength},
 		{"avg(c_int_d)", mysql.TypeNewDecimal, charset.CharsetBin, mysql.BinaryFlag, 15, 4},
 		{"avg(c_float_d)", mysql.TypeDouble, charset.CharsetBin, mysql.BinaryFlag, mysql.MaxRealWidth, types.UnspecifiedLength},
 		{"avg(c_double_d)", mysql.TypeDouble, charset.CharsetBin, mysql.BinaryFlag, mysql.MaxRealWidth, types.UnspecifiedLength},
 		{"avg(c_decimal)", mysql.TypeNewDecimal, charset.CharsetBin, mysql.BinaryFlag, 10, 7},
+		{"avg(cast(c_decimal as decimal(65,3)))", mysql.TypeNewDecimal, charset.CharsetBin, mysql.BinaryFlag, 65, 7},
 		{"avg(1.0)", mysql.TypeNewDecimal, charset.CharsetBin, mysql.BinaryFlag, 7, 5},
 		{"avg(1.2e2)", mysql.TypeDouble, charset.CharsetBin, mysql.BinaryFlag, mysql.MaxRealWidth, types.UnspecifiedLength},
 		{"avg(c_char)", mysql.TypeDouble, charset.CharsetBin, mysql.BinaryFlag, mysql.MaxRealWidth, types.UnspecifiedLength},