It’s not uncommon to promote a server from slave to master. One of the key things to protect your data integrity is to make sure that the promoted slave is permanently disconnected from its old master. If not, it may get writes from the old master, which can cause all kinds of data corruption. MySQL [...]
Disconnecting a replication slave is easier with MySQL 5.5+ (RESET SLAVE vs. RESET SLAVE ALL)
April 17, 2013 By 2 Comments
Repair MySQL 5.6 GTID replication by injecting empty transactions
March 26, 2013 By 1 Comment
In a previous post I explained how to repair MySQL 5.6 GTID replication using two different methods. I didn’t mention the famous SET GLOBAL SQL_SLAVE_SKIP_COUNTER = n for a simple reason, it doesn’t work anymore if you are using MySQL GTID. Then the question is: Is there any easy way to skip a single transaction? [...]
MySQL Backup tools used by Percona Remote DBA for MySQL
March 13, 2013 By 8 Comments
As part of Percona Remote DBA for MySQL service we recognize that reliable backups are one of the most important things we can bring to the table. In my experience handling emergencies, the single worst thing that can happen is finding out you don’t have backups available when some sort of data loss or catastrophic [...]
Replication checksums in MySQL 5.6
February 15, 2013 By 3 Comments
MySQL 5.6 has an impressive list of improvements. Among them, replication checksums caught my attention as it seems that many people misunderstand the real added value of this new feature. I heard people think that with replication checksums, data integrity between the master and its replicas is now enforced. As we’ll see, it’s not that [...]
How does MySQL Replication really work?
January 9, 2013 By 9 Comments
While we do have many blog posts on replication on our blog, such as on replication being single-threaded, on semi-synchronous replication or on estimating replication capacity, I don’t think we have one that covers the very basics of how MySQL replication really works on the high level. Or it’s been so long ago I can’t [...]
Percona XtraDB Cluster (PXC): what about GRA_*.log files ?
December 19, 2012 By Leave a Comment
How easy is it to identify and debug Percona XtraDB Cluster replication problem ? If you are using PXC, you may have already seen in your datadirectory several log files starting with GRA_ Those files correspond to a replication failure. That means the slave thread was not able to apply one transaction. For each of [...]
Migrating several single standalone MySQL server to one Percona XtraDB Cluster… MariaDB to the rescue !
December 18, 2012 By 3 Comments
Some weeks ago I had to migrate some independent MySQL servers (some standard MySQL masters, and some just standalone) to a Percona XtraDB Cluster of 3 nodes. So the easiest way would be to configure each node to become also an asynchronous slave of one of the production servers. Like illustrated here: But in this [...]
Quickly finding unused indexes (and estimating their size)
December 5, 2012 By 2 Comments
I had a customer recently who needed to reduce their database size on disk quickly without a lot of messy schema redesign and application recoding. They didn’t want to drop any actual data, and their index usage was fairly high, so we decided to look for unused indexes that could be removed. Collecting data It’s [...]
Debugging MySQL SSL problems
November 8, 2012 By Leave a Comment
This is not necessarily going to be a comprehensive post, but I learned somethings about MySQL SSL today that I thought would be worth sharing. I was setting up a PRM install for a customer and one of the requirements was SSL replication. In this particular case, I had setup PRM first, and then was [...]
Here’s a quick way to Foresee if Replication Slave is ever going to catch up and When!
August 29, 2012 By 11 Comments
If you ever had a replication slave that is severely behind, you probably noticed that it’s not catching up with a busy master at a steady pace. Instead, the “Seconds behind master” is going up and down so you can’t really tell whether the replica is catching up or not by looking at just few [...]
