MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0

17.12 InnoDB and Online DDL

The online DDL feature provides support for instant and in-place table alterations and concurrent DML. Benefits of this feature include:


ALGORITHM=INSTANT support is available for ADD COLUMN and other operations in MySQL 8.0.12.

Typically, you do not need to do anything special to enable online DDL. By default, MySQL performs the operation instantly or in place, as permitted, with as little locking as possible.

You can control aspects of a DDL operation using the ALGORITHM and LOCK clauses of the ALTER TABLE statement. These clauses are placed at the end of the statement, separated from the table and column specifications by commas. For example:


The LOCK clause may be used for operations that are performed in place and is useful for fine-tuning the degree of concurrent access to the table during operations. Only LOCK=DEFAULT is supported for operations that are performed instantly. The ALGORITHM clause is primarily intended for performance comparisons and as a fallback to the older table-copying behavior in case you encounter any issues. For example: