by Stephane Combaudon | Mar 2, 2015 | Insight for DBAs, MySQL, Percona Software
From time to time people wonder how to implement roles in MySQL. This can be useful for companies having to deal with many user accounts or for companies with tight security requirements (PCI or HIPAA for instance). Roles do not exist in regular MySQL but here is an... by Stephane Combaudon | Feb 19, 2015 | MySQL
In a previous post, titled “Multi-threaded replication with MySQL 5.6: Use GTIDs,” I explained that using GTID replication is almost a requirement when using MySQL 5.6 MTS. Let’s see now how to perform the day-to-day operations when MTS and GTIDs are... by Stephane Combaudon | Feb 13, 2015 | MySQL, Percona Software
Say you have a cluster with 3 nodes using Percona XtraDB Cluster (PXC) 5.6 and one asynchronous replica connected to node1. If asynchronous replication is using GTIDs, moving the replica so that it is connected to node2 is trivial, right? Actually replication can... by Stephane Combaudon | Feb 10, 2015 | Insight for DBAs, MySQL, Percona Software
Global Transaction IDs (GTIDs) are one of my favorite features of MySQL 5.6. The main limitation is that you must stop all the servers at the same time to allow GTID-replication. Not everyone can afford to take a downtime so this requirement has been a showstopper for... by Stephane Combaudon | Jan 29, 2015 | Insight for DBAs, MySQL
MySQL 5.6 allows you to execute replicated events in parallel as long as data is split across several databases. This feature is named “Multi-Threaded Slave” (MTS) and it is easy to enable by setting slave_parallel_workers to a > 1 value. However if you... by Stephane Combaudon | Dec 30, 2014 | MySQL, Percona Software
State Snapshot Transfer (SST) is used in Percona XtraDB Cluster (PXC) when a new node joins the cluster or to resync a failed node if Incremental State Transfer (IST) is no longer available. SST is triggered automatically but there is no magic: If it is not configured... by Stephane Combaudon | Dec 18, 2014 | Insight for DBAs, MySQL, Percona Software
HAProxy is frequently used as a software load balancer in the MySQL world. Peter Boros, in a past post, explained how to set it up with Percona XtraDB Cluster (PXC) so that it only sends queries to available nodes. The same approach can be used in a regular... by Stephane Combaudon | Dec 1, 2014 | Insight for DBAs, MySQL, Percona Software
By default in MySQL 5.6, each time MySQL is started (regular start or crash recovery), it iterates through all the binlog files when GTIDs are not enabled. This can take a very long time if you have a large number of binary log files. MySQL and Percona Server 5.6.21+... by Stephane Combaudon | Nov 24, 2014 | Insight for DBAs, MySQL
People using OpenStack Trove instances can hit a common issue in the MySQL world: how to perform schema change operations while minimizing the impact on the database server? Let’s explore the options that can allow online schema changes. Summary With MySQL 5.5,... by Stephane Combaudon | Nov 17, 2014 | Insight for DBAs, MySQL
Even if a Galera node looks like a regular MySQL server, the underlying replication mechanism is very different. This implies some changes in the way you have to configure the Galera nodes. Here are some of the most common misconceptions about Galera when using this... by Stephane Combaudon | Nov 4, 2014 | MySQL, Percona Software
Percona Toolkit’s pt-table-checksum is a great tool to find data inconsistencies between a MySQL master and its replicas. However it is sometimes not enough to know that there are inconsistencies and let pt-table-sync fix the issue: you may want to know which... by Stephane Combaudon | Oct 7, 2014 | Insight for DBAs, MySQL, Percona Services
I’ve recently worked with customers using replication rings with 4+ servers; several servers accepting writes. The idea behind this design is always the same: by having multiple servers, you get high availability and by having multiple writer nodes, you get... by Stephane Combaudon | Oct 3, 2014 | Insight for DBAs, MySQL
HAProxy is frequently used as a load-balancer in front of a Galera cluster. While diagnosing an issue with HAProxy configuration, I realized that logging doesn’t work out of the box on CentOS 6.5. Here is a simple recipe to fix the issue.If you look at the top... by Stephane Combaudon | Sep 29, 2014 | Insight for DBAs, MySQL
MySQL is the database of choice for most OpenStack components (Ceilometer is a notable exception). If you start with a small deployment, it will probably run like a charm. But as soon as the dataset grows, you will suddenly face several challenges. We will write a... by Stephane Combaudon | Sep 5, 2014 | MySQL, Percona Services, Webinars
Thank you to all of you who attended my webinar last week about Global Transaction IDs (GTIDs), which were introduced in MySQL 5.6 to make the reconfiguration of replication straightforward. If you missed my webinar, you can still listen to the recording and download... by Stephane Combaudon | Aug 20, 2014 | Insight for DBAs, MySQL, Percona Services, Webinars
Reconfiguring replication has always been a challenge with MySQL. Each time the replication topology has to be changed, the process is tedious and error-prone because finding the correct binlog position is not straightforward at all. Global Transaction IDs (GTIDs)... by Stephane Combaudon | Jul 25, 2014 | Insight for DBAs, MySQL, Percona Software
Monitoring flow control in a Galera cluster is very important. If you do not, you will not understand why writes may sometimes be stalled. Percona XtraDB Cluster 5.6 provides 2 status variables for such monitoring: wsrep_flow_control_paused and... by Stephane Combaudon | Jul 21, 2014 | Insight for DBAs, MySQL, Percona Software
I recently worked on a case where one node of a Galera cluster had its schema desynchronized with the other nodes. And that was although Total Order Isolation method was in effect to perform the schema changes. Let’s see what happened. Background For those of... by Stephane Combaudon | Jul 3, 2014 | Insight for DBAs, MySQL
In the previous post of this series we saw how you could use mysqlrpladmin to perform manual failover/switchover when GTID replication is enabled in MySQL 5.6. Now we will review mysqlfailover (version 1.4.3), another tool from the MySQL Utilities that can be used for... by Stephane Combaudon | Jun 27, 2014 | Insight for DBAs, MySQL
MySQL Utilities are a set of tools provided by Oracle to perform many kinds of administrative tasks. When GTID-replication is enabled, 2 tools can be used for slave promotion: mysqlrpladmin and mysqlfailover. We will review mysqlrpladmin (version 1.4.3) in this post....