Mysql invalidating query lindsay dating video
If you run in default mode you can also use SQL_NO_CACHE to block caching for certain queries, which you know do not need to be cached.
Counting query cache efficiency There are few ways you can look at query_cache efficiency. As you can see we have to add Qcache_hits to Com_select to get total number of queries as if query cache hit happens Com_select is not incremented.
Finally I do not want to hack wordpress to support eaccelerator cache or memcached.
Well honestly speaking if performance would be problem I should have started with full page caching rather than My SQL level caching but it is other story.
My SQL has a great feature called “Query Cache” which is quite helpful for My SQL Performance optimization tasks but there are number of things you need to know. This means it is much more efficient as query which required processing millions of rows now can be instantly summoned from query cache.
First let me clarify what My SQL Query Cache is – I’ve seen number of people being confused, thinking My SQL Query Cache is the same as Oracle Query Cache – meaning cache where execution plans are cached. It also means query has to be exactly the same and deterministic, so hit rate would generally be less. Query cache is great for certain applications, typically simple applications deployed on limited scale or applications dealing with small data sets.
In prepared statements there is query with placeholders and additional parameter values which would need extra care – it is not implemented.
Cursors get data in chunks so it is even harder to implement.
Not really it depends on which queries are cached, as well as overhead query cache provides.Only SELECT queries are cached SHOW commands or stored procedure calls are not, even if stored procedure would simply preform select to retrieve data from table.Avoid comment (and space) in the start of the query – Query Cache does simple optimization to check if query can be cached.Lets talk a bit about features and limitations of Query Cache: Transparent Caching – Caching is fully transparent to the application, and what is very important it does not change semantics of the queries – you always get actual query results.Really there are some chevats – if you’re not using query_cache_wlock_invalidate=ON locking table for write would not invalidate query cache so you can get results even if table is locked and is being prepared to be updated.