…Table Cache Related Allocations There are cases when MySQL will allocate a lot of memory for table cache, …excessive memory usage you might look at how it uses MySQL to identify potential causes. Is it …you can do better as you can query temporary tables too: mysql> select sum(data_length+index_length…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 2 Comments
…=’join_cache_incremental=on’ optimizer_switch=’join_cache_hashed=on’ optimizer_switch=’join_cache_bka=on’ join_cache_level=…10; In-memory workload Now let’s see how effective are the join optimizations when the …to 6M, the query time for MySQL 5.6 becomes approximately equal to that of MySQL 5.5. …
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
… in preparation for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a… optimizer enhancement Index Condition Pushdown (ICP). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’s take…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… case of MySQL 5.5 and ~5 hours in case of MySQL 5.6 and MariaDB 5.5. Note that query cache is disabled… desc LIMIT 20; In-memory workload Now let’s see how effective is MRR when the workload fits entirely in memory… when the correct query execution plan is not used, there is no difference in query times between MySQL 5.5 and MySQL 5.6…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
… also get information about the all-important battery-backed write cache, how it’s configured and what its status is. I can… top 10 most expensive queries, in total execution time. By the way, the slow query logs in the stock MySQL server are extremely… in the slow query log output. The stock MySQL server’s limitation of one-second granularity makes it hide problem queries that are…
Post: MySQL Query Cache
July 27, 2006 By 69 Comments
… how much work is saved 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 Configuration I…
Post: Should we give a MySQL Query Cache a second chance ?
April 10, 2011 By 63 Comments
… enough. Improve Manageability What is in the MySQL Query Cache ? How many hits did we get for this query item ? Right now none of such… hard to understand how exactly MySQL Query Cache is working in many cases. This however can be improved and data about Query Cache content and operation…
Post: Cache Performance Comparison
August 9, 2006 By 73 Comments
… are: Cache Type Cache Gets/sec Array Cache 365000 APC Cache 98000 File Cache 27000 Memcached Cache (TCP/IP) 12200 MySQL Query Cache (TCP/IP) 9900 MySQL Query Cache (Unix … is about results and how we can use them for MySQL Performance tuning ? Not surpising associative array cache performs the best,…
Post: Cache Miss Storm
September 10, 2010 By 29 Comments
… take a look at MySQL Slow queries – which is good enough if you populate each cache item with single query. Optimize query if you can… than starting populating it. For MySQL Query Cache the solution should have been to make queries wait on first query started to complete. Unfortunately this… been implemented so far. Pre-Populate the cache In some cases you can’t change how caching works easily, especially if it is…
Post: MySQL 4 to MySQL 5 Upgrade performance regressions
June 6, 2007 By 8 Comments
…extremely unhappy how MySQL handled this problem. While working for MySQL we spotted this problem early in MySQL 5…. behavior on 5.0 of MySQL being slow but few queries being “inside innodb” and potentially … battery backed up cache unit and make sure you set your RAID cache policy to “write back…
