On Wed, Mar 31, 2010 at 9:47 PM, sangprabv <sangpr...@gmail.com> wrote: > Hi, > I run mysqltuner this morning and I got these warning: > [!!] Key buffer size / total MyISAM indexes: 12.0G/23.2G > [!!] Key buffer hit rate: 76.9% > [!!] Query cache efficiency: 0.0% > [!!] Temporary tables created on disk: 27% > [!!] Table cache hit rate: 5% > > And mysqltuner recommends to adjust these setting: > key_buffer_size (> 23.2G) > query_cache_limit (> 1M, or use smaller result sets) > tmp_table_size (> 64M) > max_heap_table_size (> 128M) > table_cache (> ) > > My physical RAM is only 16Gb. I am afraid it will freezed the server if I set > key_buffer_size (> 23.2G). Any suggestion to optimize it? Thanks for any > response. > > > > > sangprabv > sangpr...@gmail.com
I would not worry much at all about the three top lines of what you posted. Before I became a DBA I worked as a dev on a not small website where we used the ultra conservative default configuration. If you do no know what you are doing you can easily cause far more harm than good by mistuning your configuration. In fact, if you have 16GB of RAM and have devoted 12GB to key buffer you have probably significantly over allocated. Keep in mind that MyISAM using the OS file system cache to cache table data. 1. Are you currently having a performance problem? If so, what queries are slow? Posting the query + the explain would help us help you. 2. Are you using any other table types other than MyISAM? If not, why not? MyISAM has horrible characteristics for many workloads due to a lack of row level locks. MyISAM also can easily corrupt. Keep in mind that this will change how a server should be tuned 3. It is probably worthwhile to try to tune table and thread cache to sane levels. 4. Having well indexed and well written queries will probably help you far more than any server tunning. 5. How are you going to test any changes to configuration? -- Rob Wultsch wult...@gmail.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
