Shinguz's blog

MySQL has introduced the PERFORMANCE_SCHEMA (P_S) in MySQL 5.5 and made it really usable in MySQL 5.6 and added some enhancements in MySQL 5.7 and 8.0.

The Chemnitz Linux Days 2018 in Chemnitz (Germany) 10/11 March 2018 are over for more than a week now and IMHO it was a huge success.

I was following many very interesting talks, met a lot of interesting people and learned a lot!

FromDual has the pleasure to announce the release of the new version 2.0.0 of its popular MySQL, Galera Cluster and MariaDB multi-instance environment MyEnv.

The new MyEnv can be downloaded here. How to install MyEnv is described in the MyEnv Installation Guide.

Due to the increasing demand FromDual has developed an Advanced MySQL Enterprise Training for DBAs and DevOps. After testing this training extensively with some selected customers last year we offer this MySQL Enterprise Training in 2018 for a broader audience.

The MySQL Enterprise Training addresses MySQL DBAs and DevOps which are already familiar with MySQL and approach now the challenge to operate a serious MySQL Enterprise infrastructure.

Yesterday MySQL 8.0.4-rc came out. The Release Notes are quite long.
But caution: Do a BACKUP before upgrading...

I experienced some nice surprises. First I have to admit that I did not read the Release Notes or anything else. Reading manuals is for Girlies! Possibly something is written in there which is of importance. But I expect that it just works as usual...

FromDual offers short term a Percona XtraDB Cluster and MySQL Galera Cluster training (2 days) in English.

The training will take place in the Linuxhotel in Essen/Germany on February 7/8 2018.

There are already enough registrations so it is certain the training will take place. But there are still free places for some additional participants.

End of February, from February 26 to March 2 (5 days), FromDual offers an additional training for DBAs and DevOps: our most visited Advanced MySQL and MariaDB training.

This training is hold in the training facilities of the FromDual training partner GFU Cyrus GmbH in Cologne-Deutz (Germany).

There are already enough registrations so it is certain the training will take place. But there are still free places for at least 3 additional participants.

The training is in German.

As in every quarter of the year Oracle has released yesterday its recommendation for the MySQL security updates. This is called, in Oracle terminology, Critical Patch Update (CPU) Advisory.

This CPU is published for all Oracle products. But FromDual is only interested in MySQL related topics. So let us concentrate on those.

Today we had to investigate in a very strange behaviour of IST and SST on a MariaDB Galera Cluster.

The symptom was, that some Galera Cluster nodes took a very long time to start. Up to 7 minutes. So the customer was concluding that the Galera Cluster node does an SST instead of an IST and was asking why the SST happens.

It have to be mentioned here, that the MariaDB error log is very confusing about whether it is an SST or an IST. So the customer was confused and concluded, that MariaDB Galera Cluster was doing an SST instead of IST.

The Docker version of the distributions are often quite old. On Ubuntu 16.04 for example:

shell> docker --version 
Docker version 1.13.1, build 092cba3

But the current docker version is 17.09.0-ce (2017-09-26). It seems like they have switched from the old version schema x.y.z to the new year.month.version version schema in February/March 2017.

Important: FromDual does NOT recommend to use an automated VIP fail-over technology as described below for a MariaDB/MySQL Master/Master Replication. In such a topology we recommend a manual VIP failover with prepared scripts!

Some of our customers still want to have old-style MariaDB Master/Master Replication Clusters. Time goes by, new technologies appear but some old stuff still remains.

There are some pretty sophisticated Load Balancers for Galera Clusters setups out in the market (ProxySQL, MaxScale, HAproxy, ...). They have many different exotic features. You can nearly do everything with them. But this comes at the cost of complexity. Non of them is simple any more.

Recently I switched on the MariaDB slow query logging flag log_queries_not_using_indexes just for curiosity on one of our customers systems:

We have sometimes discussions with our customers whether to store LOBs (Large Objects) in the database or not. To not rephrase the arguments again and again I have summarized them in the following lines.

The following items are more or less valid for all large data types (BLOB, TEXT and theoretically also for JSON and GIS columns) stored in a MySQL or MariaDB (or any other relational) database.

Preparing the MySQL Enterprise Administrator Training I found that the MySQL Enterprise Backup Incremental Backup is not described very well. Thus I tried it out and wrote down this how-to:

Incremental Differential Backup

The PAM authentication plugin is an extension included in MySQL Enterprise Edition (since 5.5) and in MariaDB (since 5.2).

When we do Galera Cluster consulting we always discuss with the customer if his software is Galera Cluster ready. This basically means: Can the software cope with the Galera Cluster specifics?

If it is a software product developed outside of the company we recommend to ask the software vendor if the software supports Galera Cluster or not.

We typically see 3 different answers:

From time to time we see in customer engagements that MySQL Master/Slave replication is set-up doing schema or table level replication filtering. This can be done either on Master or on Slave. If filtering is done on the Master (by the binlog_{do|ignore}_db settings), the binary log becomes incomplete and cannot be used for a proper Point-in-Time-Recovery. Therefore FromDual recommends AGAINST this approach.

MySQL is well known and widely spread because of its philosophy of Keep it Simple (KISS).

We recently had the discussion that with newer releases also MySQL and MariaDB relational databases becomes more and more complicated.

As you probably know MySQL is an Open Source product licensed under the GPL v2. The GPL grants you the right to not just read and understand the code of the product but also to use, modify AND redistribute the code as long as you follow the GPL rules.

In our current project the customer wants to install and run multiple MySQL Enterprise Server 5.7 Instances on the same machine (yes, I know about virtualization (we run on kvm), containers, Docker, etc.). He wants to use Red Hat Enterprise Linux (RHEL) 7 which brings the additional challenge of SystemD. So mysqld_multi is NOT an option any more.

The MySQL Server itself

The differences between the MySQL Community Server and the MySQL Enterprise Server 5.7 are as follows as claimed by Oracle:

Prepare the RPM repository server

Install the software to create a RPM repository server (on an Ubuntu web server):

shell> sudo apt-get install createrepo

Create the directory structures and initialize the repositories:

shell> sudo mkdir -p /var/www/html/repos/centos/7/os/x86_64
shell> sudo createrepo /var/www/html/repos/centos/7/os/x86_64/

Copy the MySQL Enterprise RPM packages to the repository:

If you have already Red Hat Enterprise Linux 7 (RHEL 7) or CentOS 7 in use you probably found out, that it is not that easy to install MySQL Enterprise Server because there are already pre-installed MariaDB 5.5 libraries:

Today we had a very interesting phenomena at a customer. He complained that MySQL always get some errors of the following type:

[ERROR] mysqld: Sort aborted: Error writing file '/tmp/MYGbBrpA' (Errcode: 28 - No space left on device)

After a first investigation we found that df -h /tmp shows from time to time a full disk but we could not see any file with ls -la /tmp/MY*.

After some more investigation we found even the query from the Slow Query Log which was producing the same problem. It looked similar to this query: