Percona XtraDB Cluster (PXC) has become a popular option to provide high availability for MySQL servers. However many people are still having a hard time understanding what will happen to the cluster when one or several nodes leave the cluster (gracefully or ungracefully). This is what we will clarify in this post.

Nodes leaving gracefully

Let’s assume we have a 3-node cluster and all nodes have an equal weight, which is the default.

What happens if Node1 is gracefully stopped (service mysql stop)? When shutting down, Node1 will instruct the other nodes that it is leaving the cluster. We now have a 2-node cluster and the remaining members have 2/2 = 100% of the votes. The cluster keeps running normally.

What happens now if Node2 is gracefully stopped? Same thing, Node3 knows that Node2 is no longer part of the …

Next Wednesday (June 10) I’ll be co-presenting a webinar on using MySQL in the cloud for High Availability (HA). Joining me will be 451 Research analyst Jason Stamper and together we’ll talk about the realities of HA using MySQL in the cloud and how vendors are responding to changing application requirements with new developments that can enhance your deployment.

We’ll also present a comparison of available solutions along with key best practices you can follow for successfully attaining HA in the cloud with MySQL. The webinar is scheduled for June 10 at 10 a.m. Pacific. Register here.

Together we’ll cover:

• What do HA MySQL deployments in the cloud look like …

In the MySQL Labs version of MySQL version 5.7, there is a new HTTP plugin. The HTTP plugin documentation from the labs site provides this information (from MySQL Labs):

The HTTP Plugin for MySQL adds HTTP(S) interfaces to MySQL. Clients can use the HTTP respectively HTTPS (SSL) protocol to query data stored in MySQL. The query language is SQL but other, simpler interfaces exist. All data is serialized as JSON. This version of MySQL Server HTTP Plugin is a Labs release, which means it’s at an early development stage. It contains several known bugs and limitation, and is meant primarily to give you a rough idea how this plugin will look some day. Likewise, the user API is anything but finalized. Be aware it will change in many respects.

In …

The link to the slides of my talks can be found at the end of this post but first, let me share some thoughts about PLMCE.

Talking with people, I was surprised to be criticized of presenting only the good sides of my solution without giving credit to the good side of the alternative solutions.  More than surprised, I was also a little shocked as I want to be perceived as objective as possible.  Let me try to fix that:

• I am not a GTID and log-slaves detractor, I am a simplicity lover.
• I actually like GTIDs and I have some use-cases for them; one of  them is described in the MariaDB Knowledge Base (search for last_gtid in that page).
• But I think that using GTIDs in the slave protocol is complex and that a …

I recently hosted a webinar introducing MySQL Cluster and then looking into what’s new in the latest version (MySQL Cluster 7.4) in some more detail. The replay of the MySQL Cluster 7.4 webinar is now available here. Alternatively if just want to skim through the charts then scroll down.

Abstract

MySQL Cluster powers the subscriber databases of major communication services providers as well as next generation web, cloud, social and mobile applications. It is designed to deliver:

• Real-time, in-memory performance for both OLTP and analytics workloads
• Linear scale-out for both reads and writes
• 99.999% High Availability
• Transparent, cross-shard transactions …

Note: DO NOT use this procedure in production, this is a proof of concept (POC).  MaxScale 1.1.0 does not yet fully support that procedure and things could go wrong in some situations (see at the end of the post for the details).

In my talk at PLMCE 2015, I presented an architecture to promote a slave as a new master without touching any other slave and I claimed that I tested it.  This HOWTO

Dealing with the failure of a MySQL master is not simple.  The most common solution is to promote a slave as the new master but in an environment where you have many slaves, the asynchronous implementation of replication gets in your way.  The problem is that each slave might be in a different state:

some could be very close to the dead master, some could be missing the latest transactions, and

Earlier this week, I presented a webinar on MySQL High Availability options for MySQL – what they are and how to choose the most appropriate one for your application.

The replay of this webinar can now be viewed here or if you just want to look at the charts then scroll down. At the end of this post, I include a summary of the Q&A from the webinar.

How important is your data? Can you afford to lose it? What about just some of it? What would be the impact if you couldn’t access it for a minute, an hour, a day or a week?

Different applications can have very different requirements for High Availability. Some need 100% …

Introduction

This article details the proper method of load balancing either a Percona XTRADB Cluster (PXC) or MariaDB Cluster.  Both of these solutuions utilize the same Galera plugin to facilitate clustering.  This information deatails what ports must be open and how they are to be configured as well as how to route traffic to the database nodes.

There are generally a total of three (3) nodes in this cluster, along with a single load balancer. This is the minimum number of nodes required for a cluster. This does not mean that the cluster is down if one or two nodes are lost – it only means that at least three nodes are required for normal cluster operation.

Data Centers

One of the most common questions we receive is whether the cluster can span two data centers.  The short answer is “Yes, but…”   While it is possible for a cluster to span two data centers, it …

Last weekend I got to present to the MySQL Developers Room at FOSDEM in Brussels.

The subject of my presentation was NoSQL and SQL the best of both worlds…

There’s a lot of excitement around NoSQL Data Stores with the promise of simple access patterns, flexible schemas, scalability and High Availability. The downside comes in the form of losing ACID transactions, consistency, flexible queries and data integrity checks. What if you could have the best of both worlds? This session shows how MySQL Cluster provides simultaneous SQL and native NoSQL access to your data – whether a simple key-value API (Memcached), REST, JavaScript, Java or C++. You will hear how the MySQL Cluster architecture delivers in-memory real-time performance, 99.999% availability, on-line maintenance and linear, horizontal scalability …