Shared Memory Buffer Pool

The SHM buffer pool patch, which provided the ability to use a shared memory segment for the buffer pool to enable faster server restarts, has been removed. Instead, we recommend using the LRU Dump/Restore patch which provides similar improvements in restart performance.

Replacement is due to SHM buffer pool both being very invasive and not widely used. Improved restart times are better provided by the much safer LRU D/R patch which has the advantage of also persisting across machine restarts.

The configuration variables for my.cnf have been kept for compatibility and warnings will be printed for the deprecated options (innodb_buffer_pool_shm_key and innodb_buffer_pool_shm_checksum) if used.

Instructions for disabling the SHM buffer pool can be found here.

Instructions on setting up LRU dump/restore can be found here.

Version Specific Information

• 5.1.49-rel12.0 Feature introduced.
• 5.1.50-rel12.1 System variable innodb_buffer_pool_shm_checksum added.
• 5.1.58-12.9 Feature removed, as LRU Dump/Restore is less invasive, more reliable and a better solution.

System Variables

variable innodb_buffer_pool_shm_key

Command Line:Yes Config File:Yes Scope:Global Dynamic:No Variable Type:Boolean Default Value:OFF Range:ON/OFF

variable innodb_buffer_pool_shm_checksum

Command Line:Yes Config File:Yes Scope:Global Dynamic:No Variable Type:Boolean Default Value:ON Range:ON/OFF