One of the very frequent cases with performance problems with MySQL is what they happen every so often or certain times… overloading the system causing user experience to degrade. The first thing you need to know it is not MySQL problem, might be even not problem with your MySQL configuration, queries and hardware, even though…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 3 Comments
… but it is a lot larger problems with MySQL 5.5 with addition of user variables, stored procedures, prepared statements etc which can… look at how it uses MySQL to identify potential causes. Is it working with large blobs ? Using user variables ? Prepared Statements ? memory tables… prepared statements take on server. There is no comparable variables of how many user variables are allocated (and how much memory they use…
Post: MySQL Users Conference Presentation Proposals
October 24, 2007 By 12 Comments
… feedback on what would they like to hear about on MySQL Users Conference, so I went ahead and submitted few presentation ideas… MySQL Variables Tuning This session takes practical approach to MySQL variable tuning. Instead of giving you theoretical guesses on what would be right variable values…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…MySQL manual, especially the option and variable reference table. But just as frequently, I want to look up blog posts on variables…safe_modeblogpercona.commanual safe_show_databaseblogpercona.commanual safe_user_createblogpercona.commanual secure_authblogpercona.commanual secure_file_privblogpercona…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…mysql –user=mysql –pid-file=/var/run/mysqld/mysqld.pid –skip-external-locking –port=3306 –socket=/var/db/mysql/mysql…, I’ll paste in mysql> show global variables like ‘%table_size%’; +———————+———–+ | Variable_name | Value | +———————+———–+ | max_heap_…
Post: Statement based replication with Stored Functions, Triggers and Events
December 16, 2011 By 3 Comments
… VARIABLES Local Variables are logged as an extra events before the statement itself. So all used variables are replicated on the slave. Example: mysql> SELECT YEAR(CURDATE()) INTO @this_year; mysql> insert into t VALUES… show a wrong ‘SHOW SLAVE STATUS’ output when using SET user-variables and then using it to perform writes. The issue is…
Post: Side load may massively impact your MySQL Performance
November 13, 2011 By 7 Comments
…–mysql-user=msandbox –mysql-password=msandbox –mysql-socket=/tmp/mysql_sandbox5516.sock prepare [root@localhost msb_ps_5_5_15]# sysbench –test=oltp –db-driver=mysql –mysql…just you have to enable it separately. There is a variable innodb_old_blocks_time which specifies amount of milliseconds …
Post: How much memory can MySQL use in the worst case?
February 12, 2009 By 17 Comments
… user variables — they use memory too. And they can be really big (but no bigger than max_allowed_packet). And keys for user… * 1024 * 100); Query OK, 0 rows affected (2.34 sec) mysql> select get_lock(@a, 1); +—————–+ | get_lock(@a, 1) | +—————–+ | 1… set (3.63 sec) Now I’ve got a 100M user variable and a 100M lock key. Note how long it took…
Post: How to Monitor MySQL with Percona's Nagios Plugins
February 22, 2012 By 8 Comments
… the alert spam. I’ve spoken to a lot of users with monitoring systems over the years, and everyone says that…. You can use the pmp-check-mysql-status plugin to alert when the server’s Uptime variable is too small. The server…-check-mysql-status is also very flexible and can be used to trigger an alert on almost anything from SHOW VARIABLES and…
Post: Percona Server 5.1.60-13.1
December 16, 2011 By Leave a Comment
….1 downloads and from the Percona Software Repositories). Based on MySQL 5.1.60, including all the bug fixes in it… give incorrect output with master-master replication and using SET user variables. This could only occur with a sever having both master… enabled. This is also filed in MySQL bug tracker, but not fixed in upstream MySQL at the time of this Percona Server…
