If you are using MySQL InnoDB Cluster (Group Replication) with ProxySQL, you should be familiar with the 2 functions and 1 view required in SYS Schema that ProxySQL uses to see if a node is online, partitioned or not, and if it’s lagging or not (see link1 and link2).

I received recently a very valuable contribution from Bruce DeFrang that fixes a bug in one of the function that were added to SYS.

In fact, Bruce discovered that when a node was in RECOVERING state, it was not …

For the third year in a row, we will take advantage of the mass presence of our MySQL Engineers during FOSDEM to organize the pre-FOSDEM MySQL Day.

The program of this 3rd edition is already on track, thank you to all the speakers who already confirmed their participation.

In the first part of this howto, I illustrated how to setup two MySQL InnoDB Cluster linked by an asynchronous replication.

In that solution, I didn’t use any replication filters to ignore the replication of the InnoDB Cluster’s metadata (mysql_innodb_cluster_metadata), but I used the same metadata tables with two different clusters in it.

The benefit is that this allows to backup everything from any node in any of the data center, it works also in MySQL 5.7, and there is not risk to mess up with the replication filters.

In this blog I will show how to use replication filters to link two different clusters. This doesn’t work on …

As you know, MySQL InnoDB Cluster is a High Availability solution for MySQL. However more and more people are trying to use it as a Disaster Recovery solution with 2 data centers. Natively, this is not yet supported. But it’s already possible to realize such setup if we agree with the following points:

•  a human interaction is required in case of Disaster Recovery which, by my own experience, is often acceptable
• a human interaction is required if the any Primary-Master acting as asynchronous slave leaves its group  (crash, network problem, …) or becomes secondary

These are not big constraints and it’s relatively easily to deal with them.

The Architecture

The situation is as follow:

• 2 data centers (one active, one inactive, only used for disaster recovery)
• 2 MySQL InnoDB Clusters (one in each DC)
• 3 members in each …

Today I read the nice post of Bhuvanesh on the memory leak issue they experienced with MySQL. In fact when you read the post, you realize that MySQL was just following the parameters that were setup (the default of max_prepare_stmt_count is 16382 even on 5.6).

I’m still convinced that the problem should be resolved in the application even if the use of ProxySQL for multiplexing is great.

In MySQL 8.0, we have enabled the …

Has you may already know, in MySQL it is possible to set an expiration period for passwords.

It’s not always obvious to see when the password will expire. And most of the time if you don’t pay much attention you will get something like this:

ERROR 1820 (HY000): You must reset your password using
ALTER USER statement before executing this statement.

Let me share you a small query that check for how long your password is still valid in case it was created with an expiration delay or if the global default_password_lifetime is set on …

Recently, I did some maintenance on Innotop and I merged several pull requests including one to support MySQL 8.0 (thank you yoku0825 for the contribution).

As you know, Innotop is written in Perl and to be able to use it with MySQL 8.0, you need to have Perl DBD for MySQL compatible with MySQL 8.0 too (a driver that support the new default authentication plugin, caching_sha2_password).

If you are using Fedora 29, I created such package and you can download it here: …

There are multiple way to setup replication with MySQL 8.0 and our replication offer as never been so rich: asynchronous, semi-synchronous, group replication, multi-source, … and much more options !

But if you want to setup a very quick Master-Slave environment from scratch for a quick test (you can always use dbdeployer), here are some commands to make it right the first time

Requirements

You need to have MySQL 8.0 installed and running on both servers and with the same initial data (a fresh install for example). Here we use mysql1 and mysql2. We will also use GTID as it’s much more convenient.

Servers Configuration

Let’s setup mysql1 first:

mysql1> SET PERSIST server_id=1; 
mysql1> SET …

We saw in the previous post that MySQL likes memory. We also saw how to perform operating system checks and some configuration changes for Swap and NUMA.

Today, we will check what MySQL server can tell us about its memory usage.

Introduced in MySQL 5.7 and enabled by default in MySQL 8.0, the Performance_Schema‘s Memory instrumentation allows us to have a better overview of what MySQL is allocating and why.

Let’s check on our MySQL server using SYS:

Pay attention that there is a bug related to how InnoDB Buffer Pool statistics are accounted in Performance_Schema. This is fixed in 8.0.13. …

As you may know, sometimes MySQL can be memory-hungry. Of course having data in memory is always better than disk… RAM is still much faster than any SSD disk.

This is the reason why we recommended to have the working set as much as possible in memory (I assume you are using InnoDB of course).

Also this why you don’t want to use Swap for MySQL, but don’t forget that a slow MySQL is always better than no MySQL at all, so don’t forget to setup a Swap partition but try to avoid using it. In fact, I saw many people just removing the Swap partition… and then OOM Killer did its job… and mysqld is often its first victim.

MySQL allocates buffers and caches to improve performance of database operations. That process is explained in details in the manual.

In this article series, I will provide you some …