On Tue, Jun 8, 2010 at 10:57 PM, Machiel Richards <machi...@rdc.co.za> wrote: > Good morning all > > > > I would like to try and find out how you can see what is using the > query cache. > > > > My reason for asking is the following: > > > > On one of our client databases, the query cache is set to > 128Mb and the usage always varied between 5% and 53% and basically never > went above that. > > > > However, this morning I noticed that the query cache usage > is at 99.98% which is very odd for the database.
How are you determining the cache usage? I don't think 99.98% utilitzation is a bad thing. It would be preferable to wasting memory on a cache that is under-utilized. > Does anybody have an idea on how to determine why this usage > is suddenly this high and if we should look at increasing the query cache > size or not? Has a new workload been introduced to the server? The cache utilization may be indicative of a lot of small repeated queries being introduced. You can monitor the Qcache_lowmem_prunes and Qcache_free_blocks to determine if you can benefit from increased query cache size. http://www.mysqlperformanceblog.com/2006/07/27/mysql-query-cache/ > I also have a second question relating to a previous post I > sent through but never really received a definitive answer. > > > > The client database is setup with a master slave > replication, the master Innodb buffer pool usage is at 4Gb at present (no > more system memory available to increase this) > > We are starting to receive errors on the slave server > however relating to the innodb buffer pool size being used up and there is > no place to add more locks. > > > > This was found to be related to the slave server's innodb > buffer pool size that is currently still set to 8mb. I would like to know > whether it will be worth changing the value on the slave server to match > that of the master server or will this cause more problems? If the memory is available, why not use it? It seems like the default buffer pool size out of the box was just never changed. Kyong -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
