Online DDL engine cannot handle partitioned tables, so declarative migrations cannot be used

[aquarapid]

Scenario:

• Unsharded keyspace
• Recent main branch
• issue repro:

mysql> use unsharded;
Database changed
mysql> SET @@ddl_strategy='online';                                 
Query OK, 0 rows affected (0.00 sec)

mysql> CREATE TABLE t1 (     username VARCHAR(20) NOT NULL,     logdata BLOB NOT NULL,     created DATETIME NOT NULL,     PRIMARY KEY(username, created) ) PARTITION BY HASH( TO_DAYS(created) ) PARTITIONS 10;
ERROR 1149 (42000): syntax error at position 166 near 'PARTITION'
mysql> SET @@ddl_strategy='direct';                                                                    
Query OK, 0 rows affected (0.01 sec)

mysql> CREATE TABLE t1 (     username VARCHAR(20) NOT NULL,     logdata BLOB NOT NULL,     created DATETIME NOT NULL,     PRIMARY KEY(username, created) ) PARTITION BY HASH( TO_DAYS(created) ) PARTITIONS 10;
Query OK, 0 rows affected (0.08 sec)

mysql> show create table t1\G
*************************** 1. row ***************************
     Table: t1
Create Table: CREATE TABLE `t1` (
`username` varchar(20) NOT NULL,
`logdata` blob NOT NULL,
`created` datetime NOT NULL,
PRIMARY KEY (`username`,`created`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
/*!50100 PARTITION BY HASH (to_days(`created`))
PARTITIONS 10 */
1 row in set (0.00 sec)

• Commentary:
  • When DDL is executed directly (mode direct), table creation with partitions work fine
  • With DDL strategy online, we get a syntax error. This is because of the additional checks in onlineDDLStatementSanity(..) in go/vt/schema/online_ddl.go that depends on the DDL being fully parsed by the Vitess sqlparser.
  • For the regular CREATE TABLE flow, this is not normally a problem, since the initial CREATE TABLE can be run with direct mode. However, if the user wants to use declarative online DDL (https://vitess.io/docs/user-guides/schema-changes/declarative-migrations/), they are out of luck.

[aquarapid]

#8691 (merged) fixes this issue