…execution plan. (I know it doesn’t though.) Why don’t you try writing a SQL query optimizer and see how…Check out upcoming Percona Training classes in North America and Europe. Join Percona and the MySQL…
Post: Galera Flow Control in Percona XtraDB Cluster for MySQL
May 2, 2013 By 5 Comments
…time-consuming to the application. How to tell if flow control is happening and where it is coming from There are two global status variables you can check to…execute…
Post: How to Monitor MySQL with Percona's Nagios Plugins
February 22, 2012 By 11 Comments
…to include others as well. Here’s how you can use our new monitoring plugins to check…to drop the database, it will fail. These things tend to happen at inconvenient times. The pmp-check-mysql-file-privs plugin checks whether MySQL…
Post: How to convert MySQL's SHOW PROFILES into a real profile
February 20, 2012 By 12 Comments
…how much time MySQL spends in various phases of query execution…time go? mysql> SHOW PROFILE FOR QUERY 1; +———————-+———-+ | Status | Duration | +———————-+———-+ | starting | 0.000032 | | checking…
Post: How to obtain the "LES" (Last Executed Statement) from an Optimized Core Dump?
September 9, 2012 By 9 Comments
…time) First we inspect the mysql_execute_command frame: (gdb) frame 21 #21 0x00000000005a30af in mysql_execute…checking the contents of the thd array in the mysql_execute_command frame. By simply examining “surrounding” variables we’ve been able to…
Post: Troubleshooting MySQL Upgrade Performance Regressions
February 15, 2012 By Leave a Comment
… waste your time. Instead try to understand what has changed and what exactly changed for worse. I am speaking about MySQL upgrade – version… how query is written and provide the hints. Check Query Execution If query execution plan looks the same it is good to check whenever it seems to…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 5 Comments
… for duration of query execution so it is usually easy to catch them. There …deeper to check which sessions have created which temporary tables (both in memory and not): mysql> select …TIME: NULL UPDATE_TIME: NULL 3 rows in set (0.00 sec) Innodb Memory Usage Finally it is often helpful to check how…
Post: MySQL 5.6.10 Optimizer Limitations: Index Condition Pushdown
March 14, 2013 By 2 Comments
… (5.5) to just 266 (5.6), reducing the executing time by almost 5 times. Pro tip: make sure you always check the Handler status variables for post-execution analysis. So… I invite you to join me at the webinar I have prepared for this Friday, March 15: “Learn How MySQL 5.6 Makes…
Post: Profiling MySQL Memory Usage With Valgrind Massif
January 9, 2013 By 3 Comments
There are times where you need to know exactly how much memory the mysqld server (or any other program) is … to point mysqld to your settings file etc. After mysqld is properly started (check if you can login with your mysql client), you would execute whatever steps you think are necessary to increase memory usage…
Post: MySQL Upgrade Webinar Questions Followup
June 28, 2012 By 7 Comments
…to run mysql_upgrade to check if any tables need to be rebuilt for new versions. Note this only applies to…time. I would only recommend MIXED replication mode if you have something substantial to gain. Q: How…
