MyISAM Key Cache in MYSQL
MyISAM Key Cache in MYSQL ,
To minimize disk I/O, the MyISAM storage engine exploits a strategy that is used by many database management systems. It employs a cache mechanism to keep the most frequently accessed table blocks in memory:
For index blocks, a special structure called the key cache (or key buffer) is maintained. The structure contains a number of block buffers where the most-used index blocks are placed.
For data blocks, MySQL uses no special cache. Instead it relies on the native operating system file system cache.
This section first describes the basic operation of the MyISAM key cache. Then it discusses features that improve key cache performance and that enable you to better control cache operation:
Access to the key cache no longer is serialized among threads. Multiple sessions can access the cache concurrently.
You can set up multiple key caches and assign table indexes to specific caches.