InnoDB Online DDL Operations with ALGORITHM=INSTANT

Currently, the following operations are supported by InnoDB for ALGORITHM=INSTANT:

• Adding a column. See MDEV-11369 for more information.
• Dropping a column. Added in MariaDB 10.4.0. See MDEV-15562 for more information.
• Changing the order of columns. Added in MariaDB 10.4.0. See MDEV-15562 for more information.
• Increasing the length of CHAR or VARCHAR columns. See MDEV-15563 for more information.
• Converting a column from VARCHAR to CHAR, or from VARBINARY to BINARY, or from one integer type to another integer type, as long as the size is greater than or equal to the original size. Added in MariaDB 10.4.3. See MDEV-15563 for more information.
• Changing a column from NOT NULL to NULL if the ROW_FORMAT table option is set to REDUNDANT. Added in MariaDB 10.4.3. See MDEV-15563 for more information.
• Altering the PAGE_COMPRESSED or PAGE_COMPRESSION_LEVEL table options. Added in MariaDB 10.3.10. See MDEV-16328 for more information.
• Altering the WITH SYSTEM VERSIONING table option for a table. Added in MariaDB 10.3.8. See MDEV-16330 for more information.
• Dropping a CHECK constraint. See MDEV-16331 for more information.

The following will not modify any data files, so that works:

CREATE TABLE t1 (a INT, e ENUM ('red','green'));
ALTER TABLE t ADD COLUMN b INT, ALGORITHM=INSTANT;

But the following will modify data files, so an error is thrown when ALGORITHM=INSTANT is specified:

--error ER_ALTER_OPERATION_NOT_SUPPORTED_REASON
ALTER TABLE t DROP INDEX b, ALGORITHM=INSTANT;
--error ER_ALTER_OPERATION_NOT_SUPPORTED_REASON
ALTER TABLE t ADD INDEX(b), ALGORITHM=INSTANT;

These specific statement would support any other ALGORITHM option.