(mysql.info.gz) Key cache restructuring
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(mysql.info.gz) Key cache block size
(mysql.info.gz) MyISAM key cache
7.4.6.6 Restructuring a Key Cache
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A key cache can be restructured at any time by updating its parameter
values. For example:
mysql> SET GLOBAL cold_cache.key_buffer_size=4*1024*1024;
If you assign to either the `key_buffer_size' or `key_cache_block_size'
key cache component a value that differs from the component's current
value, the server destroys the cache's old structure and creates a new
one based on the new values. If the cache contains any dirty blocks,
the server saves them to disk before destroying and re-creating the
cache. Restructuring does not occur if you set other key cache
parameters.
When restructuring a key cache, the server first flushes the contents
of any dirty buffers to disk. After that, the cache contents become
unavailable. However, restructuring does not block queries that need
to use indexes assigned to the cache. Instead, the server directly
accesses the table indexes using native filesystem caching. Filesystem
caching is not as efficient as using a key cache, so although queries
will execute, a slowdown can be anticipated. Once the cache has been
restructured, it becomes available again for caching indexes assigned
to it, and the use of filesystem caching for the indexes ceases.
Info Catalog
(mysql.info.gz) Key cache block size
(mysql.info.gz) MyISAM key cache
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