June 19, 2013

Comment: EXPLAIN EXTENDED can tell you all kinds of interesting things

June 17, 2010 By 7 Comments

Oh yes, I forgot to mention explain extended is very unstable and will crash server for certain queries.. put [ site:bugs.mysql.com "explain extended" crash ] into google for proof :) be careful!

Filed Under: Insight for Developers, MySQL Tagged With: ,

Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5

April 4, 2012 By 4 Comments

…, in this post. Now let me briefly explain these optimizations. Batched Key Access Traditionally, MySQL always uses Nested Loop Join to join… BKA With this optimization the idea of MRR is further extended to improve join performance. As I told you above, when… would like to quickly explain here, and that is Hash Joins. Hash Join As I have told before MySQL has only supported…

Filed Under: Benchmarks, Insight for DBAs, MySQL Tagged With: , , , , , , , , , , , , , ,

Post: MySQL File System Fragmentation Benchmarks

March 21, 2008 By 28 Comments

… 100 1000 10000; do ./benchmark.php $i 10000000; mysql -e’drop database test1′; mysql -e’create database test1′; done; tables: 1; total… is close, the difference is perhaps explained by the fact files needed to be constantly extended (meta data updates) and reopened for…. A bit better performance in this case can be perhaps explained but a bit larger increment how tablespaces are allocated comparted…

Filed Under: Benchmarks Tagged With: ,

Comment: Extended EXPLAIN

July 27, 2006 By 9 Comments

Peter, a small correction: EXPLAIN EXTENDED was introduced in 4.1, not in 5.0 (and it is documented at http://dev.mysql.com/doc/refman/4.1/en/explain.html)

Filed Under: Insight for Developers Tagged With: ,

Post: Submit your proposal for Percona Live London 2012 Now !

August 22, 2012 By Leave a Comment

…’re looking for great talks relevant for MySQL Ecosystem it could be about MySQL and its variants as well as technologies which…’re working with MySQL or its variants on code Level and can share some prospective about internals or explain how features work… people only starting at MySQL community not just advanced topics for veterans. The call for papers is extended until August 26th to…

Filed Under: Events and Announcements, MySQL

Post: Is your MySQL Server Loaded ?

March 19, 2010 By 6 Comments

…/stress test – how do you tell if MySQL server is really loaded ? This looks like … server for example: [root@db01 ~]# mysqladmin -i1 extended | grep Threads_running | Threads_running | 1 | | Threads_running | 1 … be expecting. It may be worth to explain what value of Threads_running represents. This …

Filed Under: Benchmarks, Insight for DBAs, MySQL

Post: InnoDB: look after fragmentation

November 5, 2009 By 12 Comments

… +——————————+——-+ 2 rows in set (0.00 sec) and extended stats: # Query_time: 17.765369 Lock_time…5903053 | +—————————+ 1 row in set (2 min 8.92 sec) mysql> SHOW STATUS LIKE ‘Innodb_scan_pages%’; +——————————+——-+ | Variable_name | Value…

Filed Under: Insight for DBAs, MySQL Tagged With:

Comment: When EXPLAIN estimates can go wrong!

October 15, 2011 By 7 Comments

… ran the test on a local MySQL sandbox version 5.5.15. Before executing the explain: [root@localhost ~]# mysqladmin –defaults-file=sandboxes/msb_vanilla_5_5_15/my.sandbox.cnf extended-status | grep -i…

Filed Under: MySQL

Comment: Wishes for new "Pure PHP" MySQL driver

October 28, 2006 By 17 Comments

…explain profiling and get nice table with your query explains and tuning advice simply by enabling explain…pooling daemon implemented as a proxy for MySQL protocol supporting persistent connections would automatically … create a child from mysqli class and extend it with tons of custom behavior but…

Filed Under: Insight for Developers Tagged With:

Post: Sphinx search performance optimization: attribute-based filters

January 15, 2013 By 11 Comments

… b) attributes Speaking in MySQL terms, Full text columns are always indexed and using the very powerful extended query syntax you can… first time, it maybe a little confusing, but let me explain. Query returned 20 rows because unless you specify an explicit…? 287 records returned in 155ms. Doing the same thing in MySQL, assuming user_id is indexed and in cache, would take…

Filed Under: Insight for Developers, MySQL Tagged With: , ,
« Older Posts
Newer Posts »