This performance enhancement is primarily useful for people with a
large buffer pool size,
typically in the multi-gigabyte range. To take advantage of this
speedup, you must set the new
configuration option, and you might also adjust the
When the InnoDB buffer pool is large, many data requests can be satisfied by retrieving from memory. You might encounter bottlenecks from multiple threads trying to access the buffer pool at once. Starting in InnoDB 1.1 and MySQL 5.5, you can enable multiple buffer pools to minimize this contention. Each page that is stored in or read from the buffer pool is assigned to one of the buffer pools randomly, using a hashing function. Each buffer pool manages its own free lists, flush lists, LRUs, and all other data structures connected to a buffer pool, and is protected by its own buffer pool mutex.
To enable this feature, set the
option to a value greater than 1 (the default) up to 64 (the
maximum). This option takes effect only when you set the
innodb_buffer_pool_size to a size of 1 gigabyte
or more. The total size you specify is divided among all the
buffer pools. For best efficiency, specify a combination of
innodb_buffer_pool_size so that
each buffer pool instance is at least 1 gigabyte.
For more information about the InnoDB buffer pool, see
Section 8.9.1, “The
InnoDB Buffer Pool”.