planner, type: fix AggFieldType error when encouter unsigned and sign type

expression/constant.go

@@ -28,17 +28,21 @@ import (
 
 // NewOne stands for a number 1.
 func NewOne() *Constant {
+	retT := types.NewFieldType(mysql.TypeTiny)
+	retT.Flag |= mysql.UnsignedFlag // shrink range to avoid integral promotion
 	return &Constant{
 		Value:   types.NewDatum(1),
-		RetType: types.NewFieldType(mysql.TypeTiny),
+		RetType: retT,
 	}
 }
 
 // NewZero stands for a number 0.
 func NewZero() *Constant {
+	retT := types.NewFieldType(mysql.TypeTiny)
+	retT.Flag |= mysql.UnsignedFlag // shrink range to avoid integral promotion
 	return &Constant{
 		Value:   types.NewDatum(0),
-		RetType: types.NewFieldType(mysql.TypeTiny),
+		RetType: retT,
 	}
 }
 

planner/core/expression_rewriter_test.go

@@ -307,3 +307,39 @@ func (s *testExpressionRewriterSuite) TestIssue20007(c *C) {
 			testkit.Rows("2 epic wiles 2020-01-02 23:29:51", "3 silly burnell 2020-02-25 07:43:07"))
 	}
 }
+
+func (s *testExpressionRewriterSuite) TestIssue9869(c *C) {
+	defer testleak.AfterTest(c)()
+	store, dom, err := newStoreWithBootstrap()
+	c.Assert(err, IsNil)
+	tk := testkit.NewTestKit(c, store)
+	defer func() {
+		dom.Close()
+		store.Close()
+	}()
+
+	tk.MustExec("use test;")
+	tk.MustExec("drop table if exists t1;")
+	tk.MustExec("create table t1(a int, b bigint unsigned);")
+	tk.MustExec("insert into t1 (a, b) values (1,4572794622775114594), (2,18196094287899841997),(3,11120436154190595086);")
+	tk.MustQuery("select (case t1.a when 0 then 0 else t1.b end), cast(t1.b as signed)  from t1;").Check(
+		testkit.Rows("4572794622775114594 4572794622775114594", "18196094287899841997 -250649785809709619", "11120436154190595086 -7326307919518956530"))
+}
+
+func (s *testExpressionRewriterSuite) TestIssue17652(c *C) {
+	defer testleak.AfterTest(c)()
+	store, dom, err := newStoreWithBootstrap()
+	c.Assert(err, IsNil)
+	tk := testkit.NewTestKit(c, store)
+	defer func() {
+		dom.Close()
+		store.Close()
+	}()
+
+	tk.MustExec("use test;")
+	tk.MustExec("drop table if exists t;")
+	tk.MustExec("create table t(x bigint unsigned);")
+	tk.MustExec("insert into t values( 9999999703771440633);")
+	tk.MustQuery("select ifnull(max(x), 0) from t").Check(
+		testkit.Rows("9999999703771440633"))
+}

types/etc.go

@@ -64,6 +64,15 @@ func IsTypeTime(tp byte) bool {
 	return tp == mysql.TypeDatetime || tp == mysql.TypeDate || tp == mysql.TypeTimestamp
 }
 
+// IsTypeInteger returns a boolean indicating whether the tp is integer type.
+func IsTypeInteger(tp byte) bool {
+	switch tp {
+	case mysql.TypeTiny, mysql.TypeShort, mysql.TypeInt24, mysql.TypeLong, mysql.TypeLonglong, mysql.TypeYear:
+		return true
+	}
+	return false
+}
+
 // IsTypeNumeric returns a boolean indicating whether the tp is numeric type.
 func IsTypeNumeric(tp byte) bool {
 	switch tp {

types/field_type.go

@@ -66,15 +66,38 @@ func NewFieldTypeWithCollation(tp byte, collation string, length int) *FieldType
 // Aggregation is performed by MergeFieldType function.
 func AggFieldType(tps []*FieldType) *FieldType {
 	var currType FieldType
+	isMixedSign := false
 	for i, t := range tps {
 		if i == 0 && currType.Tp == mysql.TypeUnspecified {
 			currType = *t
 			continue
 		}
 		mtp := MergeFieldType(currType.Tp, t.Tp)
+		isMixedSign = isMixedSign || (mysql.HasUnsignedFlag(currType.Flag) != mysql.HasUnsignedFlag(t.Flag))
 		currType.Tp = mtp
 		currType.Flag = mergeTypeFlag(currType.Flag, t.Flag)
 	}
+	// integral promotion when tps contains signed and unsigned
+	if isMixedSign && IsTypeInteger(currType.Tp) {
+		bumpRange := false // indicate one of tps bump currType range
+		for _, t := range tps {
+			bumpRange = bumpRange || (mysql.HasUnsignedFlag(t.Flag) && (t.Tp == currType.Tp || t.Tp == mysql.TypeBit))
+		}
+		if bumpRange {
+			switch currType.Tp {
+			case mysql.TypeTiny:
+				currType.Tp = mysql.TypeShort
+			case mysql.TypeShort:
+				currType.Tp = mysql.TypeInt24
+			case mysql.TypeInt24:
+				currType.Tp = mysql.TypeLong
+			case mysql.TypeLong:
+				currType.Tp = mysql.TypeLonglong
+			case mysql.TypeLonglong:
+				currType.Tp = mysql.TypeNewDecimal
+			}
+		}
+	}
 
 	return &currType
 }
@@ -311,10 +334,10 @@ func MergeFieldType(a byte, b byte) byte {
 }
 
 // mergeTypeFlag merges two MySQL type flag to a new one
-// currently only NotNullFlag is checked
-// todo more flag need to be checked, for example: UnsignedFlag
+// currently only NotNullFlag and UnsignedFlag is checked
+// todo more flag need to be checked
 func mergeTypeFlag(a, b uint) uint {
-	return a & (b&mysql.NotNullFlag | ^mysql.NotNullFlag)
+	return a & (b&mysql.NotNullFlag | ^mysql.NotNullFlag) & (b&mysql.UnsignedFlag | ^mysql.UnsignedFlag)
 }
 
 func getFieldTypeIndex(tp byte) int {

types/field_type_test.go

@@ -327,6 +327,44 @@ func (s *testFieldTypeSuite) TestAggFieldTypeForTypeFlag(c *C) {
 	c.Assert(aggTp.Flag, Equals, mysql.NotNullFlag)
 }
 
+func (s testFieldTypeSuite) TestAggFieldTypeForIntegralPromotion(c *C) {
+	fts := []*FieldType{
+		NewFieldType(mysql.TypeTiny),
+		NewFieldType(mysql.TypeShort),
+		NewFieldType(mysql.TypeInt24),
+		NewFieldType(mysql.TypeLong),
+		NewFieldType(mysql.TypeLonglong),
+		NewFieldType(mysql.TypeNewDecimal),
+	}
+
+	for i := 1; i < len(fts)-1; i++ {
+		tps := fts[i-1 : i+1]
+
+		tps[0].Flag = 0
+		tps[1].Flag = 0
+		aggTp := AggFieldType(tps)
+		c.Assert(aggTp.Tp, Equals, fts[i].Tp)
+		c.Assert(aggTp.Flag, Equals, uint(0))
+
+		tps[0].Flag = mysql.UnsignedFlag
+		aggTp = AggFieldType(tps)
+		c.Assert(aggTp.Tp, Equals, fts[i].Tp)
+		c.Assert(aggTp.Flag, Equals, uint(0))
+
+		tps[0].Flag = mysql.UnsignedFlag
+		tps[1].Flag = mysql.UnsignedFlag
+		aggTp = AggFieldType(tps)
+		c.Assert(aggTp.Tp, Equals, fts[i].Tp)
+		c.Assert(aggTp.Flag, Equals, mysql.UnsignedFlag)
+
+		tps[0].Flag = 0
+		tps[1].Flag = mysql.UnsignedFlag
+		aggTp = AggFieldType(tps)
+		c.Assert(aggTp.Tp, Equals, fts[i+1].Tp)
+		c.Assert(aggTp.Flag, Equals, uint(0))
+	}
+}
+
 func (s *testFieldTypeSuite) TestAggregateEvalType(c *C) {
 	defer testleak.AfterTest(c)()
 	fts := []*FieldType{