InnoDB System Variables • innodb_undo_log_encrypt • innodb_undo_log_truncate • innodb_undo_tablespaces For more information, see Truncating Undo Tablespaces. The  innodb_purge_rseg_truncate_frequency  variable can be used to expedite truncation of undo tablespaces. When enabled, undo 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. Controls encryption of undo log data for tables encrypted using the  InnoDB  data-at-rest encryption feature. Only applies to undo logs that reside in separate undo tablespaces. See Section 15.6.3.4, “Undo Tablespaces” . Encryption is not supported for undo log data that resides in the system tablespace. For more information, see Undo Log Encryption. Command-Line Format --innodb-undo-log-encrypt[={OFF|ON}] System Variable innodb_undo_log_encrypt Scope Global Dynamic Yes SET_VAR  Hint Applies No Type Boolean Default Value OFF Command-Line Format --innodb-undo-log-truncate[={OFF|ON}] System Variable innodb_undo_log_truncate Scope Global Dynamic Yes SET_VAR  Hint Applies No Type Boolean Default Value ON Command-Line Format --innodb-undo-tablespaces=# Deprecated Yes System Variable innodb_undo_tablespaces Scope Global Dynamic Yes SET_VAR  Hint Applies No Type Integer Default Value 2 Minimum Value 2 3295