cherry pick pingcap#18855 to release-4.0

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

expression/integration_test.go

@@ -6690,6 +6690,24 @@ func (s *testIntegrationSerialSuite) TestIssue18702(c *C) {
 	tk.MustQuery("SELECT * FROM t FORCE INDEX(idx_bc);").Check(testkit.Rows("1 A 10 1", "2 B 20 1"))
 }
 
+func (s *testIntegrationSuite) TestIssue18850(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t, t1")
+	tk.MustExec("create table t(a int, b enum('A', 'B'));")
+	tk.MustExec("create table t1(a1 int, b1 enum('B', 'A'));")
+	tk.MustExec("insert into t values (1, 'A');")
+	tk.MustExec("insert into t1 values (1, 'A');")
+	tk.MustQuery("select /*+ HASH_JOIN(t, t1) */ * from t join t1 on t.b = t1.b1;").Check(testkit.Rows("1 A 1 A"))
+
+	tk.MustExec("drop table t, t1")
+	tk.MustExec("create table t(a int, b set('A', 'B'));")
+	tk.MustExec("create table t1(a1 int, b1 set('B', 'A'));")
+	tk.MustExec("insert into t values (1, 'A');")
+	tk.MustExec("insert into t1 values (1, 'A');")
+	tk.MustQuery("select /*+ HASH_JOIN(t, t1) */ * from t join t1 on t.b = t1.b1;").Check(testkit.Rows("1 A 1 A"))
+}
+
 func (s *testIntegrationSerialSuite) TestIssue18662(c *C) {
 	collate.SetNewCollationEnabledForTest(true)
 	defer collate.SetNewCollationEnabledForTest(false)

util/codec/codec.go

@@ -359,13 +359,15 @@ func encodeHashChunkRowIdx(sc *stmtctx.StatementContext, row chunk.Row, tp *type
 			return
 		}
 	case mysql.TypeEnum:
-		flag = uvarintFlag
+		flag = compactBytesFlag
 		v := uint64(row.GetEnum(idx).ToNumber())
-		b = (*[8]byte)(unsafe.Pointer(&v))[:]
+		str := tp.Elems[v-1]
+		b = ConvertByCollation(hack.Slice(str), tp)
 	case mysql.TypeSet:
-		flag = uvarintFlag
+		flag = compactBytesFlag
 		v := uint64(row.GetSet(idx).ToNumber())
-		b = (*[unsafe.Sizeof(v)]byte)(unsafe.Pointer(&v))[:]
+		str := tp.Elems[v-1]
+		b = ConvertByCollation(hack.Slice(str), tp)
 	case mysql.TypeBit:
 		// We don't need to handle errors here since the literal is ensured to be able to store in uint64 in convertToMysqlBit.
 		flag = uvarintFlag
@@ -567,9 +569,10 @@ func HashChunkSelected(sc *stmtctx.StatementContext, h []hash.Hash64, chk *chunk
 				buf[0], b = NilFlag, nil
 				isNull[i] = true
 			} else {
-				buf[0] = uvarintFlag
+				buf[0] = compactBytesFlag
 				v := uint64(column.GetEnum(i).ToNumber())
-				b = (*[sizeUint64]byte)(unsafe.Pointer(&v))[:]
+				str := tp.Elems[v-1]
+				b = ConvertByCollation(hack.Slice(str), tp)
 			}
 
 			// As the golang doc described, `Hash.Write` never returns an error.
@@ -586,9 +589,10 @@ func HashChunkSelected(sc *stmtctx.StatementContext, h []hash.Hash64, chk *chunk
 				buf[0], b = NilFlag, nil
 				isNull[i] = true
 			} else {
-				buf[0] = uvarintFlag
+				buf[0] = compactBytesFlag
 				v := uint64(column.GetSet(i).ToNumber())
-				b = (*[sizeUint64]byte)(unsafe.Pointer(&v))[:]
+				str := tp.Elems[v-1]
+				b = ConvertByCollation(hack.Slice(str), tp)
 			}
 
 			// As the golang doc described, `Hash.Write` never returns an error.