ddl: fix add a PK when the table's pk_is_handle is true (#18340) (#18342

)

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

ddl/ddl_api.go

@@ -3288,7 +3288,9 @@ func (d *ddl) CreatePrimaryKey(ctx sessionctx.Context, ti ast.Ident, indexName m
 	}
 
 	indexName = model.NewCIStr(mysql.PrimaryKeyName)
-	if indexInfo := t.Meta().FindIndexByName(indexName.L); indexInfo != nil {
+	if indexInfo := t.Meta().FindIndexByName(indexName.L); indexInfo != nil ||
+		// If the table's PKIsHandle is true, it also means that this table has a primary key.
+		t.Meta().PKIsHandle {
 		return infoschema.ErrMultiplePriKey
 	}
 

ddl/serial_test.go

@@ -132,6 +132,14 @@ func (s *testSerialSuite) TestPrimaryKey(c *C) {
 		config.StoreGlobalConfig(&newCfg)
 	}()
 
+	_, err = tk.Exec("alter table primary_key_test2 add primary key(a)")
+	c.Assert(infoschema.ErrMultiplePriKey.Equal(err), IsTrue)
+	// We can't add a primary key when the table's pk_is_handle is true.
+	_, err = tk.Exec("alter table primary_key_test1 add primary key(a)")
+	c.Assert(infoschema.ErrMultiplePriKey.Equal(err), IsTrue)
+	_, err = tk.Exec("alter table primary_key_test1 add primary key(b)")
+	c.Assert(infoschema.ErrMultiplePriKey.Equal(err), IsTrue)
+
 	_, err = tk.Exec("alter table primary_key_test1 drop primary key")
 	c.Assert(err.Error(), Equals, "[ddl:206]Unsupported drop primary key when the table's pkIsHandle is true")
 	tk.MustExec("alter table primary_key_test2 drop primary key")