… run into question like this “I’m using SQL_NO_CACHE but my query is still much faster second time I run it… question is simple – because SQL_NO_CACHE only bypasses query cache but it has no change on other caches, which are MySQL Caches – Innodb Buffer Pool and Key… is also table_cache both MySQL side and Internal Innodb one which can affect query execution speed. OS Caches Operation Systems typically cache file IO…
Post: MySQL Query Cache
July 27, 2006 By 70 Comments
…also use SQL_NO_CACHE to block caching for certain queries, which you know do not need to be cached. Counting query cache efficiency …by query cache. Now lets speak a bit about Query Cache configuration and mainance. MySQL Manual is pretty good on this: Query Cache Query Cache Status Query Cache …
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
… bug: http://bugs.mysql.com/bug.php?id=67647 Metadata locking behaves differently for queries that are serviced from the Query Cache, let’s… block. Why? Because MySQL sees that the old entries in the Table Cache have to be invalidated, and any query that accesses the… how meta data locking works in 5.5 this is no longer the case, the second CREATE will simply block with…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…MySQL ….commanual no_defaultsblogpercona…query_alloc_block_sizeblogpercona.commanual query_cache_limitblogpercona.commanual query_cache_min_res_unitblogpercona.commanual query_cache_sizeblogpercona.commanual query_cache_typeblogpercona.commanual query_cache_wlock_invalidateblogpercona.commanual query…
Post: MySQL caching methods and tips
April 4, 2011 By 5 Comments
… MySQL. Popular cache methods The MySQL query cache When the query cache is enabled, MySQL examines each query to see if the contents have been stored in the query cache… is that they are persistent unlike the query cache or Memcached. There is no risk of unexpected invalidation, either. The summary …
Post: Thoughts on MySQL Replication
July 7, 2006 By 18 Comments
… cached in memory by MySQL cache or OS cache. As slaves replicate the same data and often queried in random or round robin fashion their cache… median servers to avoid master overload in such case. – No long queries – As I already wrote these cause delay in replication even… affected by long running queries. That is all for today but far from being all what can be said about MySQL Replication.
Post: New SpecJAppServer results at MySQL and Sun.
November 12, 2008 By Leave a Comment
… Hardware. As usually with results from such benchmarks there is no direct comparison available. The configuration Tom compares results to are…_cache = 16 query_cache_size = 0M thread_concurrency = 8 max_heap_table_size=200M log-output = FILE log-slow-queries=/tmp/mysql-slow.log long_query…
Post: Is there room for more MySQL IO Optimization?
January 3, 2013 By 11 Comments
…cached — system files, binary log, FRM files, MySQL MyISAM system tables etc. Starting MySQL 5.5 MySQL…| NPTL 2.15 SELinux | No SELinux detected Virtualized | No virtualization detected # Processor ################################################## Processors … and index scan queries, though this is …
Post: MySQL: Followup on UNION for query optimization, Query profiling
August 14, 2006 By 14 Comments
… not have to use the union. So changing query to: mysql> SELECT sql_no_cache name FROM people WHERE age in(18,19,20… happens during query execution – very helpful for MySQL Performance optimization: mysql> flush status; Query OK, 0 rows affected (0.00 sec) mysql> SELECT sql_no_cache name…
Post: mk-query-digest, query comments and the query cache
… this test. You can enable query cache stripping in Percona Server at runtime: mysql> set global query_cache_strip_comments=’ON’; Query OK, 0 rows affected (0.00 sec) QueryHitsMissesHitsMisses StrippingNo Stripping no comment1000 1000 1000…