…MySQL…drop_eventblogpercona.commanual Com_drop_functionblogpercona.commanual Com_drop_indexblogpercona.commanual Com_drop_procedureblogpercona.commanual Com_drop_serverblogpercona.commanual Com_drop_tableblogpercona.commanual Com_drop…
Post: Find unused indexes
June 30, 2012 By Leave a Comment
… stock MySQL we should try another approach. Percona Toolkit has a tool to check the usage of our index from the slow query… to understand. pt-index-usage reads the slow query log and execute every query with EXPLAIN to ask MySQL which indexes would it use… the impact on performance. You won’t need to drop all such indexes but it gives you an idea of which of…
Post: Slow Query Log analyzes tools
September 6, 2006 By 84 Comments
…indexes even if they take less time (–log-queries-not-using-indexes) Slow query log is great to spot really slow… – for example if you would be having drop down list of states in your application …to find more optimization candidates. So “tail -f mysql-slow.log | mysql_slow_log_filter -T 0.5 -R 1000…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
… by serve drop in performance. This especially apples to index lookus and joins which we cover later. As everything usually slows down a… benefit from using indexes. In fact even MySQL optimizer currently does not take it into account. For In memory workload index accesses might… large data sets. In MySQL single query runs as single thread (with exeption of MySQL Cluster) and MySQL issues IO requests one by…
Post: ALTER TABLE: Creating Index by Sort and Buffer Pool Size
June 27, 2012 By 4 Comments
… as following in terms of data and index size: mysql> show table status like “sbtest” \G *************************** 1. … when you’re adding/dropping/changing columns as if you just add index it will be … slow when index does not fit to memory any more. Creating Index by sort is great Creating index …
Post: MySQL extensions for hosting
April 24, 2008 By 11 Comments
…index are the most active or which are not being used at all and could be candidates for dropping…down. You can have slow query log enabled and… sec) mysql> SHOW INDEX_STATISTICS LIKE ‘hosting2%’; +——————————————–+———–+ | Index | Rows_read | …
Post: MySQL 5.5 and MySQL 5.6 default variable values differences
February 21, 2013 By 8 Comments
…INSTANCES | 1 | 8 | | QUERY_CACHE_SIZE | 0 | 1048576 | | SLOW_QUERY_LOG_FILE | /mnt/data/sandboxes/msb_5…of tables or if you do many create/drop of innodb tables. optimizer_switch is the …index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on 1 row in set (0.00 sec) mysql…
Post: DROP TABLE and stalls: Lazy Drop Table in Percona Server and the new fixes in MySQL
June 22, 2012 By 33 Comments
… reader-writer lock on the Adaptive Hash Index latch. The buffer pool mutex is a… for analysis purposes the queries in the slow log were grouped by their timestamp, giving…DROP TABLE implementation is MySQL 5.5.15, the version of MySQL used for benchmarking the new DROP TABLE implementation is MySQL…
Post: MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark
March 11, 2013 By 7 Comments
… the IO is slow (when the FS cache is cold, IO to slow IO subsystem happens) … the other secondary indexes have been pushed out of the buffer pool. mysql> select * from information_…LastDayInMonthFl tinyint, D_HolidayFl tinyint, D_WeekDayFl tinyint ); DROP TABLE IF EXISTS lineorder; CREATE TABLE IF …
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
… whose .frm files exist but have been dropped from InnoDB, for example. (The INFORMATION_SCHEMA … users in the mysql.* tables, running mk-duplicate-key-checker to find redundant indexes, and so on…hackmysql.com/scripts/mysqlsla perl mysqlsla -lt slow /path/to/slow.log By default, this outputs the …
