Galera replication is relatively new if compared to MySQL replication, which is natively supported since MySQL v3.23. Although MySQL replication is designed for master-slave unidirectional replication, it can be configured as an active master-master setup with bidirectional replication. While it is easy to set up, and some use cases might benefit from this “hack”, there are a number of caveats. On the other hand, Galera cluster is a different type of technology to learn and manage. Is it worth it?

In this blog post, we are going to compare master-master replication to Galera cluster.

Replication Concepts

Before we jump into the comparison, let’s explain the basic concepts …

On previous posts about Group Replication consistency we:

1. introduced consistency levels;
2. explained how to configure the primary failover consistency;
3. presented how to configure transaction consistency levels to achieve the consistency required by your applications.

In blog 3. we presented the consistency levels: EVENTUAL, BEFORE, AFTER and BEFORE_AND_AFTER; their scopes: SESSION, GLOBAL; and their context: whether they only impact the ongoing transaction or all concurrent transactions.…

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Open source databases are quickly becoming mainstream, so migration from proprietary engines into open source engines is a kind of an industry trend now. It also means that we DBA’s often end up having multiple database backends to manage.

In the past few blog posts, my colleague Paul Namuag and I covered several aspects of migration from Oracle to Percona, MariaDB, and MySQL. The obvious goal for the migration is to get your application up and running more efficiently in the new database environment, however it’s crucial to assure that staff is ready to support it.

Related resources

 Migration from Oracle Database to MariaDB - A Deep Dive

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MySQL Community with an APAC MySQL team are going to be part of the FOSSASIA Summit this week. We are a Bronze sponsor with a MySQL booth in the exhibition area. We are also having several talks in the Database track on Saturday, March 16, please see some of them below together with the details about the show:

• Name: FOSSASIA Summit 2019
• Place: Singapore
• Date: March 14-17, 2019
• MySQL talks in Database Track on Mar 16 in Training Room 2-1:
  • "Replication: What's New in MySQL 8.0" by Narendra S Chauhan, the Principal Technical Staff @Replication Development team. The talk is scheduled for 10:55-11:20.
  • "Upgrading to MySQL 8.0+, a more automated experience" by Nisha Gopalakrishnan, the Principal Technical Staff @MySQL Server Development team. The talk is scheduled for …

Author: Scott Stone

We are pleased to announce the general availability of SQL Diagnostic Manager for MySQL 8.8. Existing users may upgrade to this version through the Idera Customer Portal. New users may download the trial version from the Idera Website or the Monyog Website.

Rebranded from the popular Monyog product for monitoring performance of MySQL and other MySQL compatible databases, SDM for MySQL is  a comprehensive solution to monitor, alert, and diagnose the availability, health, and performance of MySQL, or MariaDB in physical, virtual, and cloud environments.

SQL Diagnostic Manager for MySQL addresses the most critical performance …

MySQL error log contains diagnostics messages such as errors, warnings and notes that occur during MySQL startup, shutdown and while the server is running. For example, a InnoDB table is corrupted and need to repaired, This will be recorded in the error log. MySQL 8.0 Error uses the MySQL component architecture for log event filtering and writing. The MySQL system variable log_error_services controls which log components to enable and the rules for filtering the log events. The component table in the mysql system database contains the information about currently loaded comments and shows which components have been registered with INSTALL COMPONENT. To confirm the components installed, you may use the SQL below:

SELECT * FROM mysql.component;

Currently the available log components are in lib/plugins:

• component_log_filter_dragnet.so
• component_log_sink_json.so
…

I have had some requests to write some blogs on the basics of using PHP and MySQL together.  This will not be a series for the experienced as it will start at a level where I will go into a lot of details but expect very few prerequisites from the reader.  If this is not you, please move on. If it is you and you read something you do not understand, please contact me to show me where I assumed too much.

PHP and MySQL are both in their mid twenties and both vital in the worlds of developers.  With the big improvements in PHP 7 and MySQL 8, I have found a lot of developers flocking to both but stymied by the examples they see as their are many details not explained. So let's get to the explaining!
1. Use the latest software
If you are not using PHP 7.2 or 7.3 (or maybe 7.1) then you are missing out in features and performance.  The PHP 5.x series is deprecated, no longer support, and …

We regularly get questions about how to set up a Galera cluster with just 2 nodes.

The documentation clearly states you should have at least 3 Galera nodes to avoid network partitioning. But there are some valid reasons for considering a 2 node deployment, e.g., if you want to achieve database high availability but have a limited budget to spend on a third database node. Or perhaps you are running Galera in a development/sandbox environment and prefer a minimal setup.

Related resources

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A customer recently asked for a TTL feature in MySQL. The idea is to automatically delete rows from a certain table after a defined lifespan, e.g. 60 seconds. This feature is common in many NoSQL databases, but it is not available in MySQL. However MySQL offers all you need to implement this. And due to partitioning much more efficient than only deleting rows. Let's test it.
tl;dr Partition the table and truncate partitions in a regular event procedure, that does the trick and comes at a fraction of the cost of regularly deleting rows.
The test case The table needs a column to keep track of row age. This can be either a "created_at" column or an "expires_at" column. ("expires_at" has the additional advantage that each row can have an individual lifespan. Not possible in many NoSQL solutions.)
So my table is
CREATE TABLE `t` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT PRIMARY KEY,
  …

This was not on the radar. I have never been proficient in Galera clusters and related technologies, and thus I hadn’t given much thought to Percona Xtradb Cluster (PXC), until Alkin approached me at FOSDEM, and proposed to extend dbdeployer features to support PXC. He mentioned that many support engineers at Percona use dbdeployer) on a daily basis and that the addition of PXC would be welcome.

I could not follow up …