…variable is too small, indicating the server has been restarted Check whether Threads_connected is approaching max_connections, which can be inconvenient to…change over time for one or more counters (e.g. queries per second) The documentation contains examples of how to…
Post: InnoDB's gap locks
March 27, 2012 By 14 Comments
… of data to other sessions. How to troubleshoot gap locks? Is possible to detect… global variable that affects all sessions and needs a server restart to change its …set.html. Conclusion MySQL uses REPEATABLE READ as the default isolation level so it needs to lock the index records and the gaps to…
Post: How Percona diagnoses MySQL server stalls
March 3, 2011 By 6 Comments
…they are used to watch the server, gather …to check for. VARIABLE=${VARIABLE:-Threads_connected} You need to change the threshold to 15, and the variable to Threads_running. Check the other settings…MySQL video/screencast blog site. Another interesting topic is how to examine a system that appears to…
Post: Helgrinding MySQL with InnoDB for Synchronisation Errors, Fun and Profit
November 24, 2011 By 2 Comments
…to the MySQL server developers. The Valgrind Memcheck tool, which is synonymous with Valgrind itself, is relatively widely used for the MySQL server…how to properly build the server to…variables and LOCK_system_variables_hash. Deadlock is possible when one connection issues SHOW VARIABLES…
Post: MySQL Server Memory Usage
May 17, 2006 By 18 Comments
…to run. Unfortunately this is as much close to impossible to be impractical. Here is why: List of rarely considered MySQL Server…how memory consumption reacts to changing various variables. For example you may find out increasing sort_buffer_size from 1MB to…
Post: How to check MySQL Config files
February 12, 2008 By 7 Comments
…MySQL users sometime had a situation when they would do changes in MySQL config file without restarting server (may be matching SET GLOBAL command to…server when would refuse to start when it restarted, either on operating system restart or recovering from MySQL Server…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…to change. We also want to know the operating mode you expect us to work in. Maybe you want us to…to look at MySQL Assuming I don’t see anything noteworthy here, I’ll move on to the MySQL server…
Post: ANALYZE: MyISAM vs Innodb
September 3, 2008 By 9 Comments
…MySQL servers are restarted frequently enough. Even once per 3 months is often enough for many workloads. Add to…set (0.00 sec) Too see the difference let me set column “c” to NULL in both tables and see how values change: mysql> update antest set…
Post: 10+ Ways to Crash or Overload MySQL
November 13, 2007 By 20 Comments
…overtaking the server. This will not really change until MySQL Server implements Global Resource Management as otherwise you can’t really control how much …. Session variables There is no restriction on how large you can set per connection variables for unprivileged user which allows to run queries …
Post: Infinite Replication Loop
October 10, 2011 By 2 Comments
… MySQL Replication. To explain what they are, how to identify them… and how to fix… When you setup MySQL replication, you define the global variable server_id, this …to change the server-id in my.cnf. You change the server-id interactively, this is an action you should never perform on a slave. “SET…
