Shinguz's blog

FromDual has the pleasure to announce the release of the new version 2.2.0 of its popular Backup and Recovery Manager for MariaDB and MySQL (brman).

See also our former articles:

• Do not underestimate performance impacts of swapping on NUMA database systems
• MariaDB and MySQL swap analysis

When we do analysis of MariaDB Database servers we also check the memory (RAM and Swap) available:

The General Query Log in MariaDB is a Log (file or table) that logs every statement sent from the Application to the MariaDB Database Server from the Connect Command to the Quit Command. A simple example you can find here:

The story goes on here.

Ups, that was a quick reaction… https://jira.mariadb.org/browse/MDEV-9077

The MySQL sys Schema is a cool thing and was mostly developed by Mark Leith and Jesper Wisborg Krogh from Oracle/MySQL. The sys Schema is based on the somehow cryptic MySQL PERFORMANCE_SCHEMA which was developed by Oracle/MySQL as well.

I could not resist! I have forked the MySQL sys Schema on GitHub.

• swappiness can have a value between 0 and 100.
• swappiness=0:
  • Kernel version 3.5 and newer: disables swappiness.
  • Kernel version older than 3.5: avoids swapping processes out of physical memory for as long as possible.
• swappiness=1:
  • Kernel version 3.5 and over: minimum swappiness without disabling it entirely.
• swappiness=100:
  • Tells the kernel to aggressively swap processes out of physical memory and move them to swap cache.

Source: How do I configure swappiness?

It is Saturday night at 23:19. Time to go to bed after a hard migration day. Just a last clean-up query before finishing: Tap tap tap. Enter! - Oops!

Why does Linux swap out pages when I have many pages cached and vm.swappiness is set to 0? Shouldn’t cached pages get resized and no swapping should occur?

If your MariaDB or MySQL database system is swapping it can have a significant impact on your database query performance! Further it can also slow down your database shutdown and thus influence the whole reboot of your machine. This is especially painful if you have only short maintenance windows or if you do not want to spend the whole night with operation tasks.

PERFORMANCE_SCHEMA is invented/developed by Oracle/MySQL. So for MariaDB it is a foreign component and not supported too well...

Some applications have the bad behaviour to CREATE or DROP tables while our FromDual Backup Manager (bman) backup is running.

FromDual has the pleasure to announce the release of the new version 0.9.1 of its popular FromDual Ops Center for MariaDB and MySQL focmm.

Caution: We have introduced an evil bug which prohibits installation of focmm. Sorry! Somehow it did pass our QA. To fix this bug update file lib/Upgrade.inc on Line 1965 as follows:

Last week at the MariaDB/MySQL Developer Training we had one participant asking some tricky questions I did not know the answer by heart.

InnoDB Page Cleaner Thread

The InnoDB Page Cleaner Thread is an InnoDB background thread that flushes dirty pages from the InnoDB Buffer Pool to disk. Prior MySQL 5.6 this action was performed by the InnoDB Master Thread.

Table of Contents

• General findings
• Migration from MySQL 5.x to MariaDB 5.5
• Migration from MySQL 5.0 to MariaDB 10.3
• Migration from MariaDB 10.0 to Percona Server 5.6
• Migration from MySQL/Percona 5.6 to MariaDB 10.0
• Migration from MySQL 5.7 to MariaDB 10.2
• Migration from MySQL 5.7 to MariaDB 10.3
• Migration from MySQL 5.7 to MariaDB 10.4
• Migration from Percona XtraDB Cluster 5.5 to MariaDB Galera Cluster 10.4
• Migration from MySQL 5.7 to MariaDB 10.5
• Migration from MySQL 5.7 to MariaDB 10.6
• Migration from MySQL 5.7 to MariaDB 10.6 on Windows

More and more MySQL users want to switch from MySQL/Percona Server to MariaDB over time or, more rarely, the other way around. This is mostly caused by the change of the default in the Linux Distributions (RHEL/CentOS 7, SLES 12, Debian 8) to MariaDB.
Up to MySQL/MariaDB 5.5 everything was quite easy, both Branches claim to be a drop-in replacement of each other. But after the separation into different forks (MariaDB 10.0 ff. vs. MySQL 5.6 ff.) we expect more and more problems migrating from one branch to the other what we call sidegrade.
Percona Server code is genetically closer to MySQL than MariaDB. So we expect to see less problems on this sidegrade.

A while ago somebody on Google Groups asked for the Uptime of a Galera Cluster. The answer is easy… Wait, no! Not so easy… The uptime of a Galera Node is easy (or not?). But Uptime of the whole Galera Cluster?

We had the problem today that a MySQL Galera Cluster node with the multi-tenancy pattern caused a lot of system time (sy 75%, load average about 30 (you really must read this article by Brendan Gregg, it is worth it!)) so we wanted to find what system calls are being used to see what could cause this issue (to verify if it is a TOC or a TDC problem: