… Cache is – I’ve seen number of people being confused, thinking MySQL Query Cache is the same as Oracle Query Cache – meaning cache where execution plans are cached. MySQL Query Cache is not. It does not cache the plan but…
Post: Write contentions on the query cache
September 5, 2012 By 5 Comments
… ‘Handler%’. EXPLAIN and Handler counters only confirmed that the execution plan seemed reasonable and that fields were correctly indexed. With SHOW… execution plan, but rather from contention/excessive waiting somewhere in the server. A good candidate for contention issues was the query cache…: why did MySQL need so many accesses to the query cache lock? The answer is in the way the query cache works. Simply…
Post: Cache Miss Storm
September 10, 2010 By 30 Comments
… or take a look at MySQL Slow queries – which is good enough if you populate each cache item with single query. Optimize… getting slow over time as data size growths or execution plan changes, you can also have some items becoming hot unexpectedly… cache to reflect it is being updated right now so you’re better wait rather than starting populating it. For MySQL Query Cache…
Post: What MySQL buffer cache hit rate should you target
June 29, 2006 By 5 Comments
… looking for. First thing which needs to be understand is – cache hit ratio can be computed differently for different engines. For… was OS or SAN cache hit rate – something you would not see otherwise. The bad luck is – MySQL currently does not provide this information (it exists in plans). The next best thing would be…
Post: MySQL Wish for 2013 - Better Memory Accounting
December 31, 2012 By 6 Comments
… memory allocation target, which could be something like “Prepared Statement Cache“, “Table Cache” etc. For global pools we need just global accounting… addition to monitoring it which I’m sure hosting providers, MySQL as a Service vendors will especially appreciate as currently they… as MySQL 5.6 is getting close to be done I imagine the planning and feature design is long started for MySQL 5…
Post: Reality of Innodb Caching
April 21, 2011 By 8 Comments
I have mentioned few times Innodb caches data in pages and even if you have working set … once before timing, so when there is enough memory to cache every single row there should not be any disk reads… can show better results in such benchmark. Falcon with plans for row cache would fair better, so I would expect better results…
Post: Reasons for MySQL Replication Lag
July 29, 2011 By 9 Comments
… which switches RAID cache in write-through mode which can cause serve performance degradation. Configuration Changes Have you changed MySQL configuration ? OS… problem for similar reason as MySQL Restart – the traffic on different boxes might be different and hence cache content. Replication Traffic Changes… which is being accessed by the queries or query execution plans. Side load on IO subsystem Could there be any side…
Post: Distro Packages, Pre-built Binaries or Compile Your Own MySQL
September 4, 2012 By 7 Comments
… be as easy as stopping MySQL, updating symlinks or your my.cnf basedir, starting MySQL and running mysql_upgrade. Unlike package managers, you… patches, need to alter MySQL‘s default behavior i.e. disabling and totally disallowing use of query cache or increasing maximum total… behave properly with MySQL? A paradigm shift like this can save your team tons of hours spent on planning, testing, troubleshooting (rinse…
Post: MySQL Limitations Part 4: One thread per connection
October 27, 2010 By 14 Comments
… post is about the way MySQL handles connections, allocating one thread per connection to the server. MySQL is a single process with… create a connection to MySQL, because it just requires creating a thread (or taking one from a cache). This is generally so… warehouse on MySQL, and in some cases for other uses too (note that most databases that do have these query plans usually…
Post: MySQL Connection Timeouts
April 19, 2011 By 4 Comments
… kernel buffer of connection requests on LISTEN socket is overflow – MySQL is not accepting connections as quickly as it needs. There… thread or take one out of the thread cache. From this point on MySQL processes network communication in multiple threads and can… If I have 100 connects/sec which means I should plan for 300 connections using 3x for “peak multiplier”. This means…
