… Performance Schema, focusing on new features that have been added in MySQL 5.6, go over the configuration and spend most time showing how you can use the wealth of information Performance Schema… excessive temporary tables and external sorts Excessive internal mutex contention Slow queries due to waits on InnoDB locks and Meta Data locks…
Post: How to convert MySQL's SHOW PROFILES into a real profile
February 20, 2012 By 12 Comments
… | 0.000002 | 0.00 | 1 | 0.0000020000 | | logging slow query | 0.000001 | 0.00 | 1 | 0.0000010000 | …show the portion of response time that wasn’t captured in the profile. The above query is something I developed for High Performance MySQL…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…I’ll paste in mysql> show global variables like ‘%table_size%’; +———————+———–+ | Variable_name …queries, in total execution time. By the way, the slow query logs in the stock MySQL…queries that are faster than one second (which in a high-performance system is virtually every query…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…Slow_launch_threadsblogpercona.commanual slow_launch_timeblogpercona.commanual Slow_queriesblogpercona.commanual slow_query_logblogpercona.commanual slow_query…
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
…MySQL 5.5.3 Metadata Locking behavior prior to MySQL 5.5.3 Prior to MySQL…query end | 0.000002 | | closing tables | 0.000003 | | freeing items | 0.000007 | | logging slow query…performed. Let’s see this scenario via a test case: session1 > start transaction; Query…
Post: Write contentions on the query cache
September 5, 2012 By 5 Comments
… of their top slow query according to pt-query-digest’s report. This query was run very frequently and had very unstable performance: during the… know more about how MySQL executes this query. So I used commands you’re probably familiar with: EXPLAIN, SHOW PROFILE, SHOW STATUS LIKE ‘Handler…
Post: MySQL Slow query log in the table
May 31, 2007 By 1 Comment
…MySQL 5.1 get MySQL slow query log logged in mysql.slow_log table instead of the file as you had… you require. Doing so however may affect your performance – updating table with a lot of indexes may …* FROM slow_log ORDER BY start_time DESC LIMIT 100) l ORDER BY start_time which shows last queries in …
Post: Visualization tools for pt-query-digest tables
August 31, 2012 By 6 Comments
…MySQL slow query logs using pt-query-digest you can store samples of each query into query…performance over time. Anemometer relies on the Percona Toolkit to do the slow query log collection. Specifically you can run pt-query…
Post: Read Buffers, mmap, malloc and MySQL Performance
September 12, 2007 By 8 Comments
…often together with strace) are great tools for MySQL Performance analyses. Too many people end tuning…get much slower than Monty results show. Mmap allocation process can be split to… ago I measured over 10 times slow down over time as memory becomes… LIMIT 10 in full table scan query you well may not…
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 28 Comments
… you can get from SHOW GLOBAL STATUS. I’ll start out by copying and pasting from the MySQL manual: Key_read_requestsThe… have a query I know is slow and is a problem for my application. I have profiled it with SHOW STATUS and I… good instrumentation in MySQL to guide your decisions. It is also not the be-all and end-all of MySQL performance, and people…
