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Displaying posts with tag: Group Replication (reset)
MySQL Group Replication, the perfect HA database backend for web hosting

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 …

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MySQL group replication: installation with Docker

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 …

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MySQL Group Replication: Videocast #1

Hi !

I’m starting a small series of videocast related to MySQL Group Replication.

As I blogged earlier this year about Single-Primary or Multi-Primary Group Replication cluster, one of the limitation of using a cluster in Multi-Primary mode is the risk linked to concurrent DDLs (as ALTER STATEMENTS).

In Group Replication, DDLs are not isolating the full cluster and write operations are not blocked. But this may lead to problems if you change the same table on two different nodes at the same time for example. This is the topic of today’s videocast:

MySQL Group Replication, Single-Primary or Multi-Primary, how to make the right decision ?

Today’s blog post is related again to MySQL Group Replication.

By default MySQL Group Replication runs in Single-Primary mode. And it’s the best option and the option you should use.

But sometimes it might happen that in very specific cases you would like to run you MGR Cluster in Multi-Primary mode: writing simultaneously on all the nodes member of the Group.

It’s of course feasible but you need to make some extra verification as not all workload are compatible with this behavior of the cluster.

Requirements

The requirements are the same as those for using MGR in Single-Primary mode:

  • InnoDB Storage Engine
  • Primary Keys
  • IPv4 Network
  • Binary Log Active
  • Slave Updates Logged
  • Binary …
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MySQL Group Replication Limitations: savepoints

Today in our series of articles related to MySQL Group Replication’s limitations, let’s have a quick look at Savepoints.

The manual is clear about this: Transaction savepoints are not supported.

The first thing to check then is if the application that will use our MySQL Group Replication Cluster is currently using savepoints.

We have two ways to find this, the first is using STATUS variables:

mysql> show global status like '%save%';
+----------------------------+-------+
| Variable_name              | Value |
+----------------------------+-------+
| Com_release_savepoint      | 2     |
| Com_rollback_to_savepoint  | 0     |
| Com_savepoint              | 4     |
| Handler_savepoint          | 0     |
| Handler_savepoint_rollback | 0     |
+----------------------------+-------+
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MySQL Group Replication and table design

Today’s article is about the first two restrictions in the requirements page of the manual:

  • InnoDB Storage Engine: data must be stored in the InnoDB transactional storage engine.
  • Primary Keys: every table that is to be replicated by the group must have an explicit primary key defined.

So the first requirement is easy to check by a simple query that list all the non InnoDB tables:

SELECT table_schema, table_name, engine, table_rows, 
       (index_length+data_length)/1024/1024 AS sizeMB 
FROM information_schema.tables 
WHERE engine != 'innodb' 
  AND table_schema NOT IN 
    ('information_schema', 'mysql', 'performance_schema');

The second one is a bit more tricky. Let me show you first how Group Replication behaves:

Case 1: no keys

Let’s create a table with no …

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How to migrate from Galera Cluster to MySQL Group Replication

In this article, I will show you how it’s possible to perform an online migration from a 3 members Galera cluster setup (in this case I’m using PXC 5.7.14) to a 3 members MySQL Group Replication cluster setup (MySQL Community 5.7.17).

Don’t forget that before adopting Group Replication as database backend, you should validate that your application do match GR requirements and limitations. When this is validated, you can start !

So first, let’s have a look at the current situation:

 

We have an application (sysbench 0.5), reading and writing to a Galera Cluster ( …

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Group Replication is GA with MySQL 5.7.17 – comparison with Galera

It’s a wonderful news, we have released MySQL 5.7.17 with Group Replication Plugin (GA quality).

From the definition, Group Replication is a multi-master update everywhere replication plugin for MySQL with built-in conflict detection and resolution, automatic distributed recovery, and group membership.

So we can indeed compare this solution with Galera from Codership which is a Replication Plugin implementing the WSREP API. WSREP, Write Set Replication,  extends the replication API to provide all the information and hooks required for true multi-master, “virtually synchronous” replication.

With Group Replication, MySQL implemented all this information …

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Performance Evaluation: MySQL 5.7 Group Replication (GA Release)

Great news: Group Replication is now officially released with MySQL 5.7.17, congratulations to everybody that worked so hard for it!

In this post I plan to share more details about the performance of Group Replication while addressing one of our frequently asked questions, which is how it performs compared to Galera.…

Percona Live Amsterdam 2016 – my slides

The slides of my joint tutorial with Kenny Gryp from Percona on MySQL InnoDB Cluster and Group Replication are now online.

We got nice questions during the session and very good feedback.

MySQL Group Replicatio in a nutshell – MySQL InnoDB Cluster from Frédéric Descamps

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