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(mysql.info.gz) Key cache block size

Info Catalog (mysql.info.gz) Index preloading (mysql.info.gz) MyISAM key cache (mysql.info.gz) Key cache restructuring
 
 7.4.6.5 Key Cache Block Size
 ............................
 
 MySQL 4.1 introduces a new `key_cache_block_size' variable on a per-key
 cache basis. This variable specifies the size of the block buffers for
 a key cache.  It is intended to allow tuning of the performance of I/O
 operations for index files.
 
 The best performance for I/O operations is achieved when the size of
 read buffers is equal to the size of the native operating system I/O
 buffers. But setting the size of key nodes equal to the size of the I/O
 buffer does not always ensure the best overall performance. When
 reading the big leaf nodes, the server pulls in a lot of unnecessary
 data, effectively preventing reading other leaf nodes.
 
 Currently, you cannot control the size of the index blocks in a table.
 This size is set by the server when the `.MYI' index file is created,
 depending on the size of the keys in the indexes present in the table
 definition.  In most cases, it is set equal to the I/O buffer size. In
 the future, this will be changed and then `key_cache_block_size'
 variable will be fully employed.
 
Info Catalog (mysql.info.gz) Index preloading (mysql.info.gz) MyISAM key cache (mysql.info.gz) Key cache restructuring
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