…to assert that XFS is the way to go for MySQL, but I’m not sure how frequently they benchmark XFS vs ext4, and how…time to do another benchmark. What I found with XFS is that, to my great surprise, changing the number of allocation groups, setting…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 3 Comments
…in most cases you do not know where exactly memory is allocated. This was not much of the problem in MySQL…TIME: NULL UPDATE_TIME: NULL 3 rows in set (0.00 sec) Innodb Memory Usage Finally it is often helpful to check how…Lock…
Post: How to Monitor MySQL with Percona's Nagios Plugins
February 22, 2012 By 8 Comments
…to monitor in MySQL. Those are only suggestions; any given deployment might want to monitor only some of them, as appropriate, and might need to…to start, impossible to dig out…locking in…how…setting is a bit like a lack of disk space: it is possible for it to be slowly approached over time, and then to…
Post: Helgrinding MySQL with InnoDB for Synchronisation Errors, Fun and Profit
November 24, 2011 By 2 Comments
…to get the most out of Memcheck. Not everything is perfect though: the manual is only partially correct in how to properly build the server to…in the daily work is to have the ability to run a selected MTR testcase under Helgrind. (For the time being, running the whole MySQL…
Post: SHOW OPEN TABLES - what is in your table cache
December 14, 2008 By 3 Comments
…how many threads are currently using this table, meaning have it locked or waiting on the table lock for this table to lock it. Name_locked…locked (or lock wait started) – MySQL anyway initializes the timer so it would not be much overhead to store that time together in…
Post: How to convert MySQL's SHOW PROFILES into a real profile
February 20, 2012 By 10 Comments
… how much time MySQL spends in various phases of query execution, but it isn’…35 rows in set (0.00 sec) It’s pretty hard to figure out what consumed the most time, because it’s sorted in…closing tables | 0.000014 | 0.01 | 2 | 0.0000070000 | | System lock | 0.000010 | 0.01 | 1 | 0.0000100000 | | query …
Post: How to use tcpdump on very busy hosts
April 18, 2011 By 17 Comments
…W time to respond to the first request. Back to the question of, “what is a very busy host?” In… (around 30% when filtering only 4 out of hundreds of active clients). While …lock file if [ -e "$TMP/$LOCKFILE" ]; then echo “$self: lock file $LOCKFILE already exists, aborting” exit 1 fi # set trap to…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…how to read these, there’s a full explanation in our book, High Performance MySQL 2nd Edition (it’s not in…out that I don’t spend a lot of time on settings and status. It is not where the greatest gains are to…in Locked status, which might be an indication that it’s time to convert MyISAM tables to …
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
…to enable logging atomically, not just for new connections as in MySQL…Lock_time: 0.000000 Rows_sent: 1 Rows_examined: 655360 use test; SET timestamp=1325145746; select count(*) from auto_inc; Compare that to…
Post: The two even more fundamental performance metrics
May 5, 2011 By 6 Comments
…how to maintain cheaply in the previous post. Here are some things we can do: Plot the data as time-series or in…time is under a millisecond — maybe it’s 50 microseconds, maybe a bit longer. This is common in MySQL…to a lock or some other queue, followed by the logjam clearing out…
