mysql performance tuning[edit]
query cache example
mysql> show status like "%Qcache%"; +-------------------------+----------+ | Variable_name | Value | +-------------------------+----------+ | Qcache_free_blocks | 1 | | Qcache_free_memory | 18481592 | | Qcache_hits | 82184 | | Qcache_inserts | 50875 | | Qcache_lowmem_prunes | 0 | #should be like 0 if not, chache size is too small | Qcache_not_cached | 28127 | | Qcache_queries_in_cache | 22048 | | Qcache_total_blocks | 44200 | +-------------------------+----------+ 8 rows in set (0.03 sec)
in the table variables is a opportunity to set some values:
mysql> show variables like "%query_cache%"; +------------------------------+----------+ | Variable_name | Value | +------------------------------+----------+ | have_query_cache | YES | | query_cache_limit | 1048576 | | query_cache_min_res_unit | 4096 | | query_cache_size | 41943040 | | query_cache_type | ON | | query_cache_wlock_invalidate | OFF | +------------------------------+----------+ 6 rows in set (0.00 sec)