InnoDB System Variables Non-zero values protect against the buffer pool being filled by data that is referenced only for a brief period, such as during a full table scan. Increasing this value offers more protection against full table scans interfering with data cached in the buffer pool. Specifies how long in milliseconds a block inserted into the old sublist must stay there after its first access before it can be moved to the new sublist. If the value is 0, a block inserted into the old sublist moves immediately to the new sublist the first time it is accessed, no matter how soon after insertion the access occurs. If the value is greater than 0, blocks remain in the old sublist until an access occurs at least that many milliseconds after the first access. For example, a value of 1000 causes blocks to stay in the old sublist for 1 second after the first access before they become eligible to move to the new sublist. The default value is 1000. This variable is often used in combination with  innodb_old_blocks_pct . For more information, see Section 15.8.3.3, “Making the Buffer Pool Scan Resistant” . For information about buffer pool management, the LRU algorithm, and eviction policies, see Section 15.5.1, “Buffer Pool” . Specifies an upper limit in bytes on the size of the temporary log files used during online DDL operations for  InnoDB  tables. There is one such log file for each index being created or table being altered. This log file stores data inserted, updated, or deleted in the table during the DDL operation. The temporary log file is extended when needed by the value of  innodb_sort_buffer_size , up to the maximum specified by  innodb_online_alter_log_max_size . If a temporary log file exceeds the upper size limit, the ALTER TABLE  operation fails and all uncommitted concurrent DML operations are rolled back. Thus, a large value for this option allows more DML to happen during an online DDL operation, but also extends the period of time at the end of the DDL operation when the table is locked to apply the data from the log. Maximum Value 2**32-1 Command-Line Format --innodb-online-alter-log-max-size=# System Variable innodb_online_alter_log_max_size Scope Global Dynamic Yes SET_VAR  Hint Applies No Type Integer Default Value 134217728 Minimum Value 65536 Maximum Value 2**64-1 Command-Line Format --innodb-open-files=# System Variable innodb_open_files Scope Global Dynamic No SET_VAR  Hint Applies No Type Integer 3269 • innodb_open_files • innodb_online_alter_log_max_size