mysql缓存.doc

mysql:mysqlmysqlSHOW VARIABLES LIKE %query_cache%;+-+-+|Variable_name | Value|+-+-+| have_query_cache | YES | query_cache_limit | 1048576 | query_cache_min_res_unit | 4096 | query_cache_size | 33554432 | query_cache_type | ON | query_cache_wlock_invalidate | OFF | +-+-+6 rows in set (0.00 sec)have_query_cache YESquery_cache_limit Select 1048576 byte /1024 = 1024kB select1024KBquery_cache_min_res_unit query cache 4096 byte 4kB1. Mysqlqurey cachequery_cache_min_res_unit mysqlquery_cache_min_res_unit mysql2. MySQLTrim4KB, 3KB1KB4KB2KB2KB1KB+2KB=3KB 3. mysql show status like qcache%;+-+-+|Variable_name | Value|+-+-+| Qcache_free_blocks | 5096 | Qcache_free_memory | 18964096 | Qcache_hits | 12192192 | Qcache_inserts | 3560370 | Qcache_lowmem_prunes | 17326 | Qcache_not_cached | 303599 | Qcache_queries_in_cache | 10201 | Qcache_total_blocks | 25937 | +-+-+8 rows in set (0.00 sec)Qcache_total_blocks Qcache_free_blocks flush query cache10 mysql show status like qcache%;+-+-+| Variable_name | Value|+-+-+| Qcache_free_blocks | 1 | Qcache_free_memory | 18539240 | Qcache_hits | 12192502 | Qcache_inserts | 3560515 | Qcache_lowmem_prunes | 17326 | Qcache_not_cached | 303607 | Qcache_queries_in_cache | 10318 | Qcache_total_blocks | 21081 | +-+-+8 rows in set (0.00 sec)Qcache_free_memory :Qcache_hits :Qcache_inserts :Qcache_lowmem_prunes :Qcache_not_cached :Qcache_queries_in_cache :Qcache_lowmem_prunes Qcache_free_blocks flush query cache High Performance MySQLquery_cache_min_res_unitquery_cache_min_res_unit = (query_cache_size - Qcache_free_memory) /Qcache_queries_in_cacheFLUSH QUERY CACHE RESET QUERY CACHEmysql type = innodbengine = innodb1START TRANSACTION BEGIN2COMMIT3ROLLBACK( COMMIT)ALTER TABLE BEGIN CREATE INDEX DROP DATABASE DROP TABLE RENAME TABLE TRUNCATE4SAVEPOINT adqoo_1ROLLBACK TO SAVEPOINT adqoo_1 adqoo_1 5SET AUTOCOMMIT = 0SQL COMMIT ROLLBACK COMMIT 66-1SELECT LOCK IN SHARE MODEcommitSELECT 6-2SELECT FOR UPDATE SELECT * FROM tablename WHERE id200id200id2005ROLLBACKinnodb_lock_wait_timeout = n 507SET SESSION|GLOBAL TRANSACTION ISOLATION LEVELREAD UNCOMMITTED | READ COMMITTED | REPEATABLE READ | SERIALIZABLE7-1SESSIONGLOBALSET7-2SET SESSION7-3SET GLOBALMYSQL8READ UNCOMMITTEDSELECTCOMMITREAD COMMITTED COMMIT SELECT REPEATABLE READCOMMIT SELECT SERIALIZABLEREPEATABLE READSELECT InnoDBMyISAMMySQL1. InnoDBFULLTEXT2. InnoDB select count(*) from tableInnoDBMyISAMcount(*) where3. AUTO_INCREMENTInnoDBMyISAM4. DELETE FROM tableInnoDB5. LOAD TABLE FROM MASTE