SQL> ALTER TABLE t1 ALTER COLUMN i SET DEFAULT 11, ALGORITHM=INSTANT, LOCK=NONE; ERROR HY000: Incorrect usage of ALGORITHM=INSTANT and LOCK=NONE/SHARED/EXCLUSIVE
如果为无法立即完成的任何操作设置了INSTANT算法,也将接收到错误
SQL> ALTER TABLE t1 ALTER COLUMN i SET DEFAULT 12, DROP COLUMN j, ALGORITHM=INSTANT; ERROR 0A000: ALGORITHM=INSTANT is not supported for this operation. Try ALGORITHM=COPY/INPLACE.
目前,InnoDB支持INSTANT算法的操作如下:
更改索引选项
重命名表(ALTER)
设置或删除default值
修改列
添加或删除虚拟列
添加列(non-generated)
mysql> CREATE TABLE t1 (a INT, b INT, KEY(b)); Query OK, 0 rows affected (0.70 sec) mysql> # Modify the index can be instant if it's a trivial change mysql> ALTER TABLE t1 DROP KEY b, ADD KEY b(b) USING BTREE, ALGORITHM = INSTANT; Query OK, 0 rows affected (0.14 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> # Rename the table through ALTER TABLE can be instant mysql> ALTER TABLE t1 RENAME TO t2, ALGORITHM = INSTANT; Query OK, 0 rows affected (0.26 sec) mysql> # SET DEFAULT to a column can be instant mysql> ALTER TABLE t2 ALTER COLUMN b SET DEFAULT 100, ALGORITHM = INSTANT; Query OK, 0 rows affected (0.09 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> # DROP DEFAULT to a column can be instant mysql> ALTER TABLE t2 ALTER COLUMN b DROP DEFAULT, ALGORITHM = INSTANT; Query OK, 0 rows affected (0.08 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> # MODIFY COLUMN can be instant mysql> ALTER TABLE t2 ADD COLUMN c ENUM('a', 'b', 'c'), ALGORITHM = INSTANT; Query OK, 0 rows affected (0.35 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> ALTER TABLE t2 MODIFY COLUMN c ENUM('a', 'b', 'c', 'd', 'e'), ALGORITHM=INSTANT; Query OK, 0 rows affected (0.12 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> # ADD/DROP virtual column can be instant mysql> ALTER TABLE t2 ADD COLUMN (d INT GENERATED ALWAYS AS (a + 1) VIRTUAL), ALGORITHM = INSTANT; Query OK, 0 rows affected (0.38 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> ALTER TABLE t2 DROP COLUMN d, ALGORITHM = INSTANT; Query OK, 0 rows affected (0.40 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> # Do two operations instantly in the same statement mysql> ALTER TABLE t2 ALTER COLUMN a SET DEFAULT 20, ALTER COLUMN b SET DEFAULT 200, ALGORITHM = INSTANT; Query OK, 0 rows affected (0.20 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> DROP TABLE t2; Query OK, 0 rows affected (0.36 sec)