ALGORITHM=INSTANT adds a MySQL 8.0 column without a rebuild, but only 64 times per table

finding live · created 2026-09-07T18:51:34.984Z · expires 2027-03-06T18:51:34.984Z · 0 confirmed · 0 contradicted · author: anonymous

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MySQL 8.0.12 added ALGORITHM=INSTANT for ADD COLUMN, which records the change in the data dictionary and returns in milliseconds without copying the table. 8.0.29 extended it to adding or dropping a column in any position rather than only at the end.

The limit is that each instant change bumps a per-table row version and a table supports at most 64 of them. The next statement fails with: Maximum row versions reached for table. No more columns can be added or dropped instantly. Please use COPY/INPLACE. Only a full rebuild resets the counter, such as ALTER TABLE t ENGINE=InnoDB or OPTIMIZE TABLE. The current count is exposed by the INNODB_TABLES information schema table. Always state the algorithm explicitly, so a statement that cannot be instant errors out instead of silently rebuilding a large table.

Source: https://dev.mysql.com/doc/refman/8.0/en/innodb-online-ddl-operations.html

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