The documentation states that “For a transaction to commit, the majority of the group have to agree on the order of a given transaction in the global sequence of transactions.”

This means that as soon as the majority of nodes member of the group ack the writeset reception, certification can start. So, as a picture is worth a 1000 words, this is what it looks like if we take the illustrations from my previous post:

a group of 3 members

zoom in transaction deliverthe writer also acksmajority is reached, the system agreed on the orderack of the remaining node will come too but the order has been already decided

certification can startthe process then continues as usual

So theoretically, having 2 nodes in one DC and 1 node in another DC shouldn’t be affected …

After some feedback we received from early adopters or discussions during events like FOSDEM, I realized that there is some misconception about the type of replication that MySQL Group Replication is using. And even experts can be confused as Vadim’s blog post illustrated it.

So, is MySQL Group Replication asynchronous or synchronous ?? … in fact it depends !

The short answer is that GR is asynchronous. The confusion here can be explained by the comparison with Galera that claims to be synchronous or virtually synchronous depending where and who claims it (Synchronous multi-master replication library, synchronous replication,  …

This blog post is my overview of Group Replication technology.

With Oracle clearly entering the “open source high availability solutions” arena with the release of their brand new Group Replication solution, I believe it is time to review the quality of the first GA (production ready) release.

TL;DR: Having examined the technology, it is my conclusion that Oracle seems to have released the GA version of Group Replication too early. While the product is definitely “working prototype” quality, the release seems rushed and unfinished. I found a significant number of issues, and I would personally not recommend it for production use.

It is obvious that Oracle is trying hard to ship technology to compete with …

In this blog post, we’ll point to a new Docker image for Percona Server for MySQL Group Replication.

Our most recent release of Percona Server for MySQL (Percona Server for MySQL 5.7.17) comes with Group Replication plugins. Unfortunately, since this technology is very new, it requires some fairly complicated steps to setup and get running. To help with that process, I’ve prepare Docker images that simplify its setup procedures.

You can find the image here: https://hub.docker.com/r/perconalab/pgr-57/.

To start the first node (bootstrap the group):

docker run -d -p 3306 --net=clusternet -e …

In this blog, we’ll discuss how to use concurrency to help with WAN latency when using synchronous clusters.

WAN Latency Problem

Our customers often ask us for help or advice with WAN clustering problems. Historically, the usual solution for MySQL WAN deployments is having the primary site in one data center, and stand-by backup site in another data center (replicating from the primary asynchronously). These days, however, there is a huge desire to employ available synchronous replication solutions for MySQL. These solutions include things like Galera (i.e., Percona XtraDB Cluster) or the recently released MySQL Group Replication. This trend is attributable to the fact that these solutions are less problematic and provide more automatic fail over and fail back procedures. But it’s also because businesses want to write in both data centers simultaneously.

Unfortunately, WAN link reliability and latency makes …

Let’s finish these pre-FOSDEM MySQL Day Sessions reviews with Kenny Gryp‘s talk on MySQL Group Replication.

Kenny is working at Percona as MySQL Practice Manager.

Group Replication went Generally Available end of 2016, it introduces a (virtually) ‘synchronous’ active:active multi-master replication, in addition to asynchronous and semi-synchronous replication, the latter 2 being available in in MySQL for longtime.

As with any new feature, and especially with introducing active:active multi-master replication, it takes a while before companies are adopting the software in production database environment.
For example, even though MySQL 5.7 has been GA for more than a year, adoption is only starting to increase recently.

We can, and should, expect the same from Group …

One of the talk will replaced in the schedule by a panel discussion moderated by Morgan Tocker on MySQL Group Replication & MySQL 8.0.

The panel list will be composed of

Kenny GrypRené CannaòØystein GrøvlenMark LeithFrédéric Descamps

These experts will answer questions from Morgan and from the audience.

Don’t miss this great opportunity to ask your questions and participate to this discussion about MySQL.

The schedule:

In my previous post, we saw the usage of MySQL Group Replication (MGR) in single-primary mode. We know that Oracle does not recommends using MGR in multi-primary mode, but there is so much in the documentation and in presentations about MGR behavior in multi-primary, that I feel I should really give it a try, and especially compare this technology with the already existing multiple master solution introduced in 5.7: multi-source replication.

Installation

To this extent, I will set up two clusters using MySQL-Sandbox. The instructions for MGR in …

Many web hosting provider are looking for HA solution for the database backend they deliver to their customers.

Galera never became the perfect choice for these environment due to 2 factors:

1. no DBA really manage the databases
2. Galera runs database changes in Total Order Isolation

What does that really mean ? In fact, when you are a website hosting provider, you host the website (apache, nginx) on vhosts and you share a database server in which every customer has access to their own schema for their website.

Most of the time, those websites are CMS like Drupal, WordPress or Joomla (and certainly many others sharing the same …

Overview

MySQL Group Replication was released as GA with MySQL 5.7.17. It is essentially a plugin that, when enabled, allows users to set replication with this new way.

There has been some confusion about the stability and usability of this release. Until recently, MySQL Group Replication (MGR) was only available in the Labs, which traditionally denotes a preview or an use-at-your-own-risk feature. Several months ago we saw the release of Group Replication as a Docker image, which allowed users to deploy a peer-to-peer cluster (every node is a master.) However, about one month after such release, word came from Oracle discouraging this setup, and inviting users to use Group Replicator in …