Try to increaze your query_cache_size until there's no more additional lowmem_prunes reported.
And executed from time to time FLUSH QUERY CACHE to defragment your query cache.
Jocelyn
Mauricio Pellegrini a écrit :
Thanks these are fresh results
| query_cache_limit | 1048576 | | query_cache_min_res_unit | 4096 |
show status like "ques%"; +---------------+----------+ | Variable_name | Value | +---------------+----------+ | Questions | 14189604 | +---------------+----------+
show status like "qcache%"; +-------------------------+----------+ | Variable_name | Value | +-------------------------+----------+ | Qcache_free_blocks | 2731 | | Qcache_free_memory | 12372064 | | Qcache_hits | 11156553 | | Qcache_inserts | 1945643 | | Qcache_lowmem_prunes | 372898 | | Qcache_not_cached | 509594 | | Qcache_queries_in_cache | 4101 | | Qcache_total_blocks | 11000 | +-------------------------+----------+
On Wed, 2005-03-09 at 20:19, Jocelyn Fournier wrote:
Hi,
How many questions for thoses results ?
There's a lot of lowmem_prunes, so I would indeed increase the memory size to reduce the risk of lowmem_prunes.
What is your query_cache_limit ?
Jocelyn
Mauricio Pellegrini a écrit :
Thanks, this the result of show status like "qcache%"
+-------------------------+----------+ | Variable_name | Value | +-------------------------+----------+ | Qcache_free_blocks | 3330 | | Qcache_free_memory | 13372320 | | Qcache_hits | 11119149 | | Qcache_inserts | 1942009 | | Qcache_lowmem_prunes | 372898 | | Qcache_not_cached | 508528 | | Qcache_queries_in_cache | 3160 | | Qcache_total_blocks | 9711 | +-------------------------+----------+
Am I right at saying that the value (16Mb)is ok ?
Qcache_not_cached means the number of query results that didn't get into
the cache because of a space limitation ? If so, perhaps adding few more Mb would improve that number , isn't it?
On Wed, 2005-03-09 at 19:30, Dan Nelson wrote:
In the last episode (Mar 09), Mauricio Pellegrini said:
Hi, I'm trying to tweak the execution time for querys on my mysql server which is using InnoDB.
I know that there are a lot of things to check but one of them, perhaps not the most important, is the query_cache_size.
I have a dual Xeon cpu with 4gb of ram and this is a Linux dedicated server which runs only Apache and Mysql 4.1.5
I've declared Query_cache_size = 16M in the my.cnf file and I would say that in the whole we have 60% of select querys and a 40% of update querys.
Is Query_cache_size=16M too conservative considering that I have 4Gb of ram ?
A better question is: what is your current utilization of that 16MB cache? The query cache flushes any results dependant on a table when that table is modified, so if you really have 40% updates, chances are that very few queries are cachable at all. Run
show status like 'qcache%';
, and take a look at free_memory, inserts, and hits.
-- Dan Nelson [EMAIL PROTECTED]
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