ddl: restricting altering the utf8 charset to utf8mb4 (#9107)

pingcap · Jan 22, 2019 · cfb6311 · cfb6311
1 parent 63936cc
commit cfb6311
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Showing 3 changed files with 65 additions and 20 deletions.
diff --git a/ddl/db_integration_test.go b/ddl/db_integration_test.go
@@ -527,24 +527,47 @@ func (s *testIntegrationSuite) TestNullGeneratedColumn(c *C) {
 func (s *testIntegrationSuite) TestChangingCharsetToUtf8(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 
-	tk.MustExec("USE test")
-	tk.MustExec("create table t(a char(10) charset latin1)")
-	tk.MustExec("alter table t modify column a char(10) charset latin1")
-	tk.MustExec("alter table t modify column a char(10) charset utf8")
-	tk.MustExec("alter table t modify column a char(10) charset utf8mb4")
-	rs, err := tk.Exec("alter table t modify column a char(10) charset utf8mb4 collate utf8bin")
+	tk.MustExec("use test")
+	tk.MustExec("create table t1(a varchar(20) charset utf8)")
+	tk.MustExec("insert into t1 values (?)", "t1_value")
+
+	tk.MustExec("alter table t1 modify column a varchar(20) charset utf8mb4")
+	tk.MustQuery("select * from t1;").Check(testkit.Rows("t1_value"))
+
+	tk.MustExec("create table t(a varchar(20) charset latin1)")
+	tk.MustExec("insert into t values (?)", "t_value")
+
+	tk.MustExec("alter table t modify column a varchar(20) charset latin1")
+	tk.MustQuery("select * from t;").Check(testkit.Rows("t_value"))
+
+	rs, err := tk.Exec("alter table t modify column a varchar(20) charset utf8")
 	if rs != nil {
 		rs.Close()
 	}
 	c.Assert(err, NotNil)
-	tk.MustExec("alter table t modify column a char(10) charset utf8mb4 collate utf8mb4_bin")
-	rs, err = tk.Exec("alter table t modify column a char(10) charset utf8 collate utf8_bin")
+	c.Assert(err.Error(), Equals, "[ddl:210]unsupported modify charset from latin1 to utf8")
+	rs, err = tk.Exec("alter table t modify column a varchar(20) charset utf8mb4")
 	if rs != nil {
 		rs.Close()
 	}
+	c.Assert(err, NotNil)
+	c.Assert(err.Error(), Equals, "[ddl:210]unsupported modify charset from latin1 to utf8mb4")
 
+	rs, err = tk.Exec("alter table t modify column a varchar(20) charset utf8mb4 collate utf8bin")
+	if rs != nil {
+		rs.Close()
+	}
+	c.Assert(err, NotNil)
+	rs, err = tk.Exec("alter table t modify column a varchar(20) charset utf8 collate utf8_bin")
+	if rs != nil {
+		rs.Close()
+	}
+	c.Assert(err, NotNil)
+	rs, err = tk.Exec("alter table t modify column a varchar(20) charset utf8mb4 collate utf8mb4_general_ci")
+	if rs != nil {
+		rs.Close()
+	}
 	c.Assert(err, NotNil)
-	tk.MustExec("alter table t modify column a char(10) charset utf8mb4 collate utf8mb4_general_ci")
 }
 
 func (s *testIntegrationSuite) TestChangingTableCharset(c *C) {
@@ -557,20 +580,24 @@ func (s *testIntegrationSuite) TestChangingTableCharset(c *C) {
 		rs.Close()
 	}
 	c.Assert(err.Error(), Equals, "Unknown charset gbk")
-	tk.MustExec("alter table t charset utf8")
-	tk.MustExec("alter table t charset utf8 collate utf8_bin")
+	rs, err = tk.Exec("alter table t charset utf8")
+	if rs != nil {
+		rs.Close()
+	}
+	c.Assert(err.Error(), Equals, "[ddl:210]unsupported modify charset from latin1 to utf8")
+
 	rs, err = tk.Exec("alter table t charset utf8 collate latin1_bin")
 	if rs != nil {
 		rs.Close()
 	}
 	c.Assert(err, NotNil)
-	tk.MustExec("alter table t charset utf8mb4")
-	tk.MustExec("alter table t charset utf8mb4 collate utf8mb4_bin")
-
-	rs, err = tk.Exec("alter table t charset utf8 collate utf8_bin")
+	rs, err = tk.Exec("alter table t charset utf8mb4")
 	if rs != nil {
 		rs.Close()
 	}
+	c.Assert(err.Error(), Equals, "[ddl:210]unsupported modify charset from latin1 to utf8mb4")
+
+	rs, err = tk.Exec("alter table t charset utf8mb4 collate utf8mb4_bin")
 	c.Assert(err, NotNil)
 }
 

diff --git a/ddl/db_test.go b/ddl/db_test.go
@@ -2051,7 +2051,7 @@ func (s *testDBSuite) TestCheckTooBigFieldLength(c *C) {
 	s.tk.MustExec("create table tr_03 (id int, name varchar(65534), purchased date ) default charset=latin1;")
 
 	s.tk.MustExec("drop table if exists tr_04;")
-	s.tk.MustExec("create table tr_04 (a varchar(20000) ) default charset utf8;")
+	s.tk.MustExec("create table tr_04 (a varchar(20000)) default charset utf8;")
 	s.testErrorCode(c, "alter table tr_04 convert to character set utf8mb4;", tmysql.ErrTooBigFieldlength)
 	s.testErrorCode(c, "create table tr (id int, name varchar(30000), purchased date )  default charset=utf8 collate=utf8_bin;", tmysql.ErrTooBigFieldlength)
 	s.testErrorCode(c, "create table tr (id int, name varchar(20000) charset utf8mb4, purchased date ) default charset=utf8 collate=utf8;", tmysql.ErrTooBigFieldlength)
@@ -2063,6 +2063,26 @@ func (s *testDBSuite) TestCheckTooBigFieldLength(c *C) {
 	s.tk.MustExec("alter table tr_05 modify column a varchar(16000) charset utf8mb4;")
 }
 
+func (s *testDBSuite) TestCheckConvertToCharacter(c *C) {
+	s.tk = testkit.NewTestKit(c, s.store)
+	s.tk.MustExec("use test")
+	s.tk.MustExec("drop table if exists t")
+	defer s.tk.MustExec("drop table t")
+	s.tk.MustExec("create table t(a varchar(10) charset binary);")
+	ctx := s.tk.Se.(sessionctx.Context)
+	is := domain.GetDomain(ctx).InfoSchema()
+	t, err := is.TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
+	rs, err := s.tk.Exec("alter table t modify column a varchar(10) charset utf8 collate utf8_bin")
+	c.Assert(err, NotNil)
+	rs, err = s.tk.Exec("alter table t modify column a varchar(10) charset utf8mb4 collate utf8mb4_bin")
+	c.Assert(err, NotNil)
+	rs, err = s.tk.Exec("alter table t modify column a varchar(10) charset latin collate latin1_bin")
+	c.Assert(err, NotNil)
+	if rs != nil {
+		rs.Close()
+	}
+	c.Assert(t.Cols()[0].Charset, Equals, "binary")
+}
 func (s *testDBSuite) TestModifyColumnRollBack(c *C) {
 	s.tk = testkit.NewTestKit(c, s.store)
 	s.mustExec(c, "use test_db")

diff --git a/ddl/ddl_api.go b/ddl/ddl_api.go
@@ -1855,10 +1855,8 @@ func modifiableCharsetAndCollation(toCharset, toCollate, origCharset, origCollat
 	if !charset.ValidCharsetAndCollation(toCharset, toCollate) {
 		return ErrUnknownCharacterSet.GenWithStackByArgs(toCharset, toCollate)
 	}
-
-	if toCharset == charset.CharsetUTF8MB4 || (toCharset == charset.CharsetUTF8 && origCharset != charset.CharsetUTF8MB4) {
-		// TiDB treats all the data as utf8mb4, so we support changing the charset to utf8mb4.
-		// And not allow to change utf8mb4 to utf8.
+	if toCharset == charset.CharsetUTF8MB4 && origCharset == charset.CharsetUTF8 {
+		// TiDB only allow utf8 to be changed to utf8mb4.
 		return nil
 	}