MySQL 8 Cookbook

Managing UNDO tablespace

You can manage the size of an UNDO tablespace through the dynamic variable innodb_max_undo_log_size, which is 1 GB by default, and the number of UNDO tablespaces through innodb_undo_tablespaces, which is 2 GB by default and dynamic from MySQL 8.0.2.

By default, innodb_undo_log_truncate is enabled. Tablespaces that exceed the threshold value defined by innodb_max_undo_log_size are marked for truncation. Only undo tablespaces can be truncated. Truncating undo logs that reside in the system tablespace is not supported. For truncation to occur, there must be at least two undo tablespaces.