…secs. I dont understand why MySQL uses index merge after a… LIMIT 505 ; …| PRIMARY | 4 | oslogs_jan02_db.LinksTbl2.userid | 1 | | | 1 | SIMPLE | FileTbl | eq_ref | PRIMARY,folder_…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 3 Comments
…_table_size variable which allows you to limit size of MEMORY tables (the limit applies both to implicit and explicit … (both in memory and not): mysql> select * from information_schema.global_temporary_tables \G *************************** 1. row *************************** SESSION_ID: 7234 TABLE_…
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
…enhancement Index Condition Pushdown (ICP). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’… Condition Pushdown Traditional B-Tree index lookups have some limitations in cases such as range scans, where index …condition defined as: l_partkey = x and l_quantity >= 1 and l_quantity = 1 and l_…
Post: Percona Toolkit 2.1 with New Online Schema Change Tool
April 5, 2012 By 9 Comments
… release of version 2.1 of Percona Toolkit. Percona Toolkit is the essential suite of administrative tools for MySQL. With this release… tool, one of the most painful things anyone experiences with MySQL is significantly alleviated. If you’ve ever delayed a project…. However, it had many limitations and missing features. The new 2.1 version of the tool removes those limitations and makes the tool…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
…, n_name, c_address, c_comment order by revenue desc LIMIT 20; In-memory workload Now let’s see how effective…=4M Created_tmp_disk_tables 1 1 1 1 1 Created_tmp_tables 1 1 1 1 1 Handler_mrr_init N/A 0 0 1 1 Handler_mrr_rowid_refills N… 914146 912318 Select_scan 1 1 1 1 1 Sort_scan 1 1 1 1 1 As you can see from the status counters above that both MySQL 5.6 and…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 2 Comments
… o_shippriority order by revenue desc, o_orderdate LIMIT 10; In-memory workload Now let’s … the status counters. Counter Name MySQL 5.5 MySQL 5.6 MySQL 5.6 w/ join_buffer_size=…6718351 6611675 6707882 5479445 5527245 Select_scan 1 1 1 1 1 1 Sort_scan 1 1 1 1 1 1 The first obvious improvement is shown …
Post: Announcing Percona XtraBackup 1.9.1
February 27, 2012 By 9 Comments
… XtraBackup 2.0! We call this version 1.9.1 as we are using the 1.9.x version numbers for betas of… production use, check out our latest stable release (which was 1.6.5 at the time of writing). This beta adds…. It is now possible to stream incremental backups, lifting a limitation from previous versions where it was only possible to stream…
Post: Percona Live MySQL Conference & Expo Was A Great Event
April 17, 2012 By 2 Comments
… Live New York, which will be held October 1-2, 2012 at the Sentry Conference Center in …were available. In 2013 we have none of those limitations: the conference is a day longer and isn’…for their new development milestone release for MySQL 5.6, released on Monday. MySQL 5.6 just keeps looking …
Comment: What does Using filesort mean in MySQL?
March 15, 2012 By 27 Comments
… the “ORDER BY OPTIMIZATION” section in MySQL manual but could not find a reason why MySQL does not use index in the… BY a LIMIT 1698, 1 This one uses filesort (Extra: Using filesort): EXPLAIN SELECT * FROM table1 ORDER BY a LIMIT 1699, 1 Can someone EXPLAIN if there is a rule that MySQL uses to determine whether to use index or filesort? On mysql…
Post: Announcing Percona XtraBackup 2.0.0 GA
April 4, 2012 By 11 Comments
…release contains no changes from the last beta (1.9.2), only the version number has changed…. utilities, which also had a number of other limitations (e.g. could not be used with parallel… of the topics at the upcoming Percona Live MySQL Conference and Expo (register now!). Specifically, there are…
