Patch that addresses bug #53976 "ALTER TABLE RENAME

is allowed on views (not documented, broken)".

Remove support of ALTER TABLE RENAME for views as:
a) this feature was not documented,
c) does not add any compatibility with other databases,
b) its implementation doesn't follow metadata locking
   protocol by accessing .FRM without holding any
   metadata lock,
c) its implementation complicates ALTER TABLE's code
   by introducing  yet another separate branch to it.

After this patch one can rename a view by using the
documented way - RENAME TABLE statement.

mysql-test/r/rename.result

@@ -55,14 +55,15 @@ t2
 t4
 drop table t2, t4;
 End of 4.1 tests
+#
+# Bug#14959: "ALTER TABLE isn't able to rename a view"
+# Bug#53976: "ALTER TABLE RENAME is allowed on views
+#             (not documented, broken)"
+#
 create table t1(f1 int);
 create view v1 as select * from t1;
 alter table v1 rename to v2;
-alter table v1 rename to v2;
-ERROR 42S02: Table 'test.v1' doesn't exist
-rename table v2 to v1;
-rename table v2 to v1;
-ERROR 42S01: Table 'v1' already exists
+ERROR HY000: 'test.v1' is not BASE TABLE
 drop view v1;
 drop table t1;
 End of 5.0 tests

mysql-test/r/view.result

@@ -3954,6 +3954,7 @@ drop procedure p;
 CREATE TABLE t1 (a INT);
 CREATE VIEW v1 AS SELECT a FROM t1;
 ALTER TABLE v1;
+ERROR HY000: 'test.v1' is not BASE TABLE
 DROP VIEW v1;
 DROP TABLE t1;
 #

mysql-test/t/rename.test

@@ -79,17 +79,15 @@ connection default;
 --echo End of 4.1 tests
 
 
-#
-# Bug#14959: ALTER TABLE isn't able to rename a view
-#
+--echo #
+--echo # Bug#14959: "ALTER TABLE isn't able to rename a view"
+--echo # Bug#53976: "ALTER TABLE RENAME is allowed on views
+--echo #             (not documented, broken)"
+--echo #
 create table t1(f1 int);
 create view v1 as select * from t1;
+--error ER_WRONG_OBJECT
 alter table v1 rename to v2;
---error ER_NO_SUCH_TABLE
-alter table v1 rename to v2;
-rename table v2 to v1;
---error ER_TABLE_EXISTS_ERROR
-rename table v2 to v1;
 drop view v1;
 drop table t1;
 

mysql-test/t/view.test

@@ -3902,6 +3902,7 @@ drop procedure p;
 --echo #
 CREATE TABLE t1 (a INT);
 CREATE VIEW v1 AS SELECT a FROM t1;
+--error ER_WRONG_OBJECT
 ALTER TABLE v1;
 DROP VIEW v1;
 DROP TABLE t1;

sql/sql_table.cc

@@ -6454,8 +6454,6 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
   char reg_path[FN_REFLEN+1];
   ha_rows copied,deleted;
   handlerton *old_db_type, *new_db_type, *save_old_db_type;
-  legacy_db_type table_type;
-  frm_type_enum frm_type;
   enum_alter_table_change_level need_copy_table= ALTER_TABLE_METADATA_ONLY;
 #ifdef WITH_PARTITION_STORAGE_ENGINE
   uint fast_alter_partition= 0;
@@ -6535,91 +6533,6 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
     /* Conditionally writes to binlog. */
     DBUG_RETURN(mysql_discard_or_import_tablespace(thd,table_list,
 						   alter_info->tablespace_op));
-  strxnmov(new_name_buff, sizeof (new_name_buff) - 1, mysql_data_home, "/", db, 
-           "/", table_name, reg_ext, NullS);
-  (void) unpack_filename(new_name_buff, new_name_buff);
-  /*
-    If this is just a rename of a view, short cut to the
-    following scenario: 1) lock LOCK_open 2) do a RENAME
-    2) unlock LOCK_open.
-    This is a copy-paste added to make sure
-    ALTER (sic:) TABLE .. RENAME works for views. ALTER VIEW is handled
-    as an independent branch in mysql_execute_command. The need
-    for a copy-paste arose because the main code flow of ALTER TABLE
-    ... RENAME tries to use open_ltable, which does not work for views
-    (open_ltable was never modified to merge table lists of child tables
-    into the main table list, like open_tables does).
-    This code is wrong and will be removed, please do not copy.
-  */
-  frm_type= dd_frm_type(thd, new_name_buff, &table_type);
-  /* Rename a view */
-  /* Sic: there is a race here */
-  if (frm_type == FRMTYPE_VIEW && !(alter_info->flags & ~ALTER_RENAME))
-  {
-    /*
-      The following branch handles "ALTER VIEW v1 /no arguments/;"
-      This feature is not documented one. 
-      However, before "OPTIMIZE TABLE t1;" was implemented, 
-      ALTER TABLE with no alter_specifications was used to force-rebuild
-      the table. That's why this grammar is allowed. That's why we ignore
-      it for views. So just do nothing in such a case.
-    */
-    if (!new_name)
-    {
-      my_ok(thd);
-      DBUG_RETURN(FALSE);
-    }
-
-    /*
-      Avoid problems with a rename on a table that we have locked or
-      if the user is trying to to do this in a transcation context
-    */
-
-    if (thd->locked_tables_mode || thd->in_active_multi_stmt_transaction())
-    {
-      my_message(ER_LOCK_OR_ACTIVE_TRANSACTION,
-                 ER(ER_LOCK_OR_ACTIVE_TRANSACTION), MYF(0));
-      DBUG_RETURN(TRUE);
-    }
-
-    if (thd->global_read_lock.wait_if_global_read_lock(thd, FALSE, TRUE))
-      DBUG_RETURN(TRUE);
-
-    /*
-      TODO/FIXME: Get rid of this code branch if possible. To add insult
-                  to injury it breaks locking protocol.
-    */
-    table_list->mdl_request.set_type(MDL_EXCLUSIVE);
-    if (lock_table_names(thd, table_list))
-    {
-      error= 1;
-      goto view_err;
-    }
-
-    mysql_mutex_lock(&LOCK_open);
-
-    if (!do_rename(thd, table_list, new_db, new_name, new_name, 1))
-    {
-      if (mysql_bin_log.is_open())
-      {
-        thd->clear_error();
-        Query_log_event qinfo(thd, thd->query(), thd->query_length(),
-                              FALSE, TRUE, FALSE, 0);
-        if ((error= mysql_bin_log.write(&qinfo)))
-          goto view_err_unlock;
-      }
-      my_ok(thd);
-    }
-
-view_err_unlock:
-    mysql_mutex_unlock(&LOCK_open);
-    unlock_table_names(thd);
-
-view_err:
-    thd->global_read_lock.start_waiting_global_read_lock(thd);
-    DBUG_RETURN(error);
-  }
-
 
   /*
     Code below can handle only base tables so ensure that we won't open a view.