…_requests should be as low as possible, no more than 1:100″ or “your key cache hit ratio should be very … to occur. How much of this query‘s execution time is consumed by those operations? Should I try to…amount of memory based on how important those tables are to you, how big the indexes are on disk,…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
… information about the all-important battery-backed write cache, how it’s configured and what its status is…. something else is wrong. This is not a big deal for performance, it’s just something to… huge tables that should be archived, tables that I should be aware of if I see them in queries, or what…
Post: Caching techinques
August 8, 2006 By 11 Comments
…caching in files should be used with caution. It may be very efficient especially if number of cached…cache once underlying information is updated. This is how MySQL Query Cache works by removing all queries…
Post: Performance impact of complex queries
January 17, 2007 By 11 Comments
… one such query running concurrently. Lets talk a bit how it is happening and how to prevent it. Cache Wiping…In recent Linux Kernels deadline or cfq IO schedulers should be better with this. So what can you do…do not do it as all one big simple query or as set of queries going one after another. Have…
Post: Should you move from MyISAM to Innodb ?
January 12, 2009 By 59 Comments
…queries. In case MyISAM was chosen not just happened to be…Application should be ready to work with Innodb, for example be ready… clustering by primary key, caching data, higher concurrency, background… TABLE and others. Another big one is COUNT(*) without… and knows how to handle it, or be able to …
Post: MySQL 5.5.8 and Percona Server: being adaptive
December 20, 2010 By 25 Comments
… run on the FusionIO card. There I should say that we were not able…it makes an exact calculation of how many pages were handled impossible. The… optimization we have for SSDs is big log files. For this run, I… max_connections=3000 query_cache_size=0 skip-name-resolve table_cache=10000 [mysql] socket=/…
Comment: MySQL 5.5 and MySQL 5.6 default variable values differences
February 21, 2013 By 8 Comments
… smaller was a better choice for OLTP. People should be cautious about increasing the sizes of things that … not to be too big. In practice we tend to see query cache sizes that are far too big more than … about how and when to change the values. This will eventually end up in our documentation and be…
Post: Heikki Tuuri answers to Innodb questions, Part II
November 4, 2007 By 13 Comments
… time. How many read-aheads can be waiting…be big win for TableSpace files but these are much larger and so less used for the time being. What would be…OS cache? Is there special options or tricks that should be …-core scalability (concurrent queries, autoincrement, concurrent inserts, instrumentation,…
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
…table ALTER that alters a big table can keep executing without…Query Cache How does metadata locking behave with query_cache? That is an important question. If Query Cache is enabled and the SELECT can be serviced from the Query Cache…accessed on every request, then care should be taken when you have …
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
…how Shard-Query…Query for yourself. Spin up the desired number of EC2 instances using on of the the AMI images. You should…cache-size=32 thread-stack=256K tmp-table-size=64M transaction-isolation=READ-COMMITTED user=mysql wait-timeout=86400 To be…
