… denominator, and they cancel out. The key cache hit ratio is simply one minus the miss ratio. The key_buffer hit ratio The metrics we’re interested in…:100″ or “your key cache hit ratio should be very high, ideally above 99.9%” or “if your key cache hit ratio is low, your key_buffer_size is…
Post: What MySQL buffer cache hit rate should you target
June 29, 2006 By 5 Comments
…What cache hit rate is good for optimal MySQL Performance” is typical question I’m asked. It could by MyISAM key_buffer or… to be understand is – cache hit ratio can be computed differently for different engines. For example for Innodb page hits are counted for all…. Well in this case global key hit ratio may be 99.99% but you would still have problems with key buffer efficiency. In the…
Post: Cache Performance Comparison
August 9, 2006 By 73 Comments
…performance bottleneck, assuming PHP opcode cache is not used. Also different applications may have different cache hit ratios which also needs to be …KEY (`k`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; INSERT INTO `test` VALUES (‘test’,'MyTestString’); 3) You need all caches to work, ie query cache…
Post: How simple answer are you looking for ?
April 11, 2007 By 5 Comments
… Memory Compared to Your Database Size Should you Have” , “What Key Cache Hit Ratio is Good One” This often gives me head aches – I…
Post: MySQL Query Cache
July 27, 2006 By 69 Comments
… I’ve seen query cache offering about double performance for simple queries with select done by primary key, obviously there is no… bad. With other caches you may implement version based or timeout based invalidation which can offer much better hit ratio for certain application. It is not that fast Query Cache is fast compared to running…
Post: What to tune in MySQL Server after installation
September 29, 2006 By 116 Comments
… other changes will most commonly offer only incremental performance improvements. key_buffer_size – Very important if you use MyISAM tables. Set… OS cache so values up to 70-80% of memory often make sense for Innodb only installations. Same rules as for key… and see if it is well used. For certain workloads cache hit ratio is lower than would justify having it enabled. Note: as…
Post: Maatkit Now Supports Memcached
July 24, 2009 By 9 Comments
…: Burn Memory Waste Network Round-Trips Store Keys That Never Get Retrieved Have a Low Cache Hit Ratio (i.e. query MySQL too much….75k 4.35k 4.71k 1.31k 4.71k # key print 1 TEST_KEY # 17% (114) Memc_error # 100% (657) Memc_get…. instead of 100% Memc_cmd like above. –report key: Like key_print but the keys are not fingerprinted so the two examples above…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
… last failed foreign key constraint: ———————— LATEST FOREIGN KEY ERROR ———————— 060717 4… are done to OS cache, and being sequential writes …hit ratio which measures buffer pool efficiency. 1000/1000 corresponds to 100% hit rate. It is hard to tell what buffer pool hit…
Comment: Why you should ignore MySQL's key cache hit ratio
March 1, 2010 By 27 Comments
… keys can either be in Cache or on disk. Now… Tune this server by allocating RAM that you have available for the key cache, and do your tuning in such a way as to _not_ improve the standard metric of ratio of key_read_requests to key… “expensive operations” Key_reads, opened_tables, created_tmp_disk_tables more than the ratio of the “expensive operation” to the “cache hit” I must…
Comment: What to tune in MySQL Server after installation
October 23, 2006 By 116 Comments
…. For instance, INNODB_BUFFER_POOL_SIZE… how can I evaluate hit ratios to determine if this is undersized? Sure, I may see… using the query cache and key cache? I’ve noticed in the Administrator GUI tool you can see hit ratios for query cache and key cache in myISAM…
