A while ago I wrote about how to make MySQL replication reliable, part of which is to eliminate temporary tables. The idea is this: if a slave is stopped (or crashed) while a temporary table is open and is then restarted, the temporary table doesn’t exist anymore, and the slave will have problems trying to [...]
Concurrent inserts on MyISAM and the binary log
May 14, 2008 By 7 Comments
Recently I had an interesting surprise with concurrent inserts into a MyISAM table. The inserts were not happening concurrently with SELECT statements; they were blocking and the process list was filling up with queries in Locked status. My first thought was that the customer had deleted from the table, which leaves “holes” in the middle [...]
Using MMM to ALTER huge tables
March 27, 2008 By 11 Comments
Few months ago, I wrote about a faster way to do certain table modifications online. It works well when all you want is to remove auto_increment or change ENUM values. When it comes to changes that really require table to be rebuilt – adding/dropping columns or indexes, changing data type, converting data to different character [...]
No more MySQL Crash Safe Replication in 5.0 ?
January 29, 2008 By 7 Comments
As you might know even if you’re only using Innodb tables your replication is not completely crash safe – if Slave MySQL Server crashes/power goes down it is likely for relay logs to run out of sync (they are not synced to the disk) plus position on the master which slave remembers becomes stale. During [...]
Filtered MySQL Replication
November 7, 2007 By 8 Comments
To get this straight – I’m not a big fan of filtered or partial MySQL Replication (as of version MySQL 5.0) – there is enough gotchas with replication itself and getting things right with filtering can get quite bumpy road. In some applications however it is very helpful so lets see what one should do [...]
The new cool MySQL patch has landed! Check your queries performance!
October 31, 2007 By 16 Comments
Microslow patch is used by many DBAs and developers to accurately time their queries and to catch those which run less than a second as they can also be a performance killer for a busy application. Recently I have started the development of an updated version of the patch. The basic idea is the same [...]
Managing Slave Lag with MySQL Replication
October 12, 2007 By 15 Comments
The question I often get is how far MySQL may fall behind and how to keep replication from lagging. The lag you will see will vary a lot from application to the application and from load to load. Plus what is the most important within same application the lag will likely have spikes – most [...]
Microslow patch for 5.1.20
July 18, 2007 By 3 Comments
Microslow patch has been there for some time, but only for earlier MySQL editions such as 4.1 and 5.0. Now it’s also available for the latest 5.1. Because MySQL went through a lot of internal changes, the patch had to be written from scratch. It introduces some minor change in existing functionality and also adds [...]
Master-Master or Master with Many Slaves
April 6, 2007 By 7 Comments
I just found post by Kevin, in which he criticizes Master-Master approach, finding Master with many slaves more optimal. There is surely room for master-N-slaves systems but I find Master-Master replication much better approach in many cases. Kevin Writes “It requires extra hardware thats sitting in standby and not being used (more money and higher [...]
MySQL Replication and Slow Queries
March 28, 2007 By 3 Comments
I just filed a bug regarding slow queries executed by replication thread are not being logged to the slow query log. This is not a big deal but it is ugly little gotcha which I think few people know about. It is especially bad if you’re using tools to analyze slow query log to find [...]
