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Shutdown with MySQL 8

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On StackExchange for Database Administrators I recently have seen a question which attracted my interest.

The question puzzled me a bit because the answer seems too easy. Further the question was not so clear. An all theses factors smell dangerous...

innodb_deadlock_detect - Rather Hands off!

Recently we had a new customer who has had from time to time massive database problems which he did not understand. When we reviewed the MySQL configuration file (my.cnf) we found, that this customer had disabled the InnoDB Deadlock detection (innodb_deadlock_detect).

Because we have advised against doing this so far, but I never stumbled upon this problem in practice, I have investigated a bit more about the MySQL variable innodb_deadlock_detect.

FromDual is 10 years old

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On 1 March 2020 FromDual became 10 years old! Sincere thanks are given to all our customers, partners and interested person for their support and good cooperation in the last 10 years. And we would be pleased to advise and support you again competently in the coming 10 years.

Your FromDual Team

anniversary

InnoDB Page Cleaner intended loop takes too long

Recently we migrated a database system from MySQL 5.7 to MariaDB 10.3. Everything went fine so far just the following message started to pop-up in the MariaDB Error Log File with the severity Note:

InnoDB: page_cleaner: 1000ms intended loop took 4674ms. The settings might not be optimal. (flushed=102 and evicted=0, during the time.)

I remember that this message also appeared in earlier MySQL 5.7 releases but somehow disappeared in later releases. I assume MySQL has just disabled the Note?

FromDual Ops Center for MariaDB and MySQL 0.9.3 has been released

FromDual has the pleasure to announce the release of the new version 0.9.3 of its popular FromDual Ops Center focmm, a Graphical User Interface (GUI) for MariaDB and MySQL.

The FromDual Ops Center for MariaDB and MySQL (focmm) helps DBA's and System Administrators to better manage their MariaDB and MySQL database farms. Ops Center makes DBA and Admins life easier!

FromDual Performance Monitor for MariaDB and MySQL 1.1.0 has been released

FromDual has the pleasure to announce the release of the new version 1.1.0 of its popular Database Performance Monitor for MariaDB, MySQL and Galera Cluster fpmmm.

The FromDual Performance Monitor for MariaDB and MySQL (fpmmm) enables DBAs and System Administrators to monitor what is going on inside their MariaDB and MySQL databases and on their machines where the databases reside.

Migration from MySQL 5.7 to MariaDB 10.4

Up to version 5.5 MariaDB and MySQL can be considered as "the same" databases. The official wording at those times was "drop-in-replacement". But now we are a few years later and times and features changed. Also the official wording has slightly changed to just "compatible".
FromDual recommends that you consider MariaDB 10.3 and MySQL 8.0 as completely different database products (with some common roots) nowadays. Thus you should work and act accordingly.

FromDual Recovery Manager (rman) with progress indicator

Since version 2.1.0 the FromDual Recovery Manager (rman) for MariaDB and MySQL has also a progress indicator for the restore of logical backups made with mysqldump. This feature was implemented because of the numerous requests of FromDual rman users who were not happy with the default mysql behavior.

You can check your current rman version as follows:

# ./bin/rman --version
2.2.1

As with all FromDual tools you get a command overview with examples with the --help option:

Schulung Galera Cluster für MariaDB und MySQL im September 2019 in Berlin

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Die Sommerferien sind vorbei. Mit neuem Elan in den Herbst! Zeit für eine Weiterbildung?

Vom 19. bis 20. September führt FromDual wieder die Galera Cluster Schulung Galera Cluster für MySQL und MariaDB in Berlin durch. Siehe auch unsere weiteren Schulungstermine.

FromDual Ops Center for MariaDB and MySQL 0.9.2 has been released

FromDual has the pleasure to announce the release of the new version 0.9.2 of its popular FromDual Ops Center for MariaDB and MySQL focmm.

The FromDual Ops Center for MariaDB and MySQL (focmm) helps DBA's and System Administrators to manage MariaDB and MySQL database farms. Ops Center makes DBA and Admins life easier!

Schulung MariaDB/MySQL für Fortgeschrittene im August 2019 in Köln

Sommerferien-Zeit – für all die Daheimgebliebenen dürfte es jetzt hoffentlich etwas ruhiger zu und her gehen. Zeit für eine Weiterbildung? Es bleibt nicht mehr viel Zeit, das Jahres-Schulungs-Budget aufzubrauchen!

Vom 19. bis 23. August führt FromDual wieder einmal die Schulung MariaDB und MySQL für Fortgeschrittene in Köln durch. Siehe auch unsere Schulungstermine.

Enable General Query Log per Connection in MariaDB

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:

MariaDB sys Schema

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The MySQL sys Schema is a cool thing and was mostly developed by Mark Leith and Jesper Wisborg Krogh from Oracle/MySQL.

Oops! - That SQL Query was not intended... Flashback

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!

SQL> UPDATE prospect_lists_prospects SET prospect_list_id = '73ae6cca-7b34-c4a3-5500-5d0e2674dbb6';
Query OK, 4686 rows affected (0.21 sec)
Rows matched: 5666  Changed: 4686  Warnings: 0

A verification query to make sure I am in the mess:

Do not underestimate performance impacts of swapping on NUMA database systems

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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.

Dropped Tables with FromDual Backup Manager

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

This leads to the following bman error message:

FromDual Ops Center for MariaDB and MySQL 0.9.1 has been released

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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.

The FromDual Ops Center for MariaDB and MySQL (focmm) helps DBA's and System Administrators to manage MariaDB and MySQL database farms. Ops Center makes DBA and Admins life easier!

FromDual Ops Center for MariaDB and MySQL 0.9 has been released

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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:

- $sql = sprintf("REPLACE INTO `focmm_configuration` (`key`, `value`) VALUES ('%s', '%s'), ('%s', '%s'), ('%s', '%s')"
+ $sql = sprintf("REPLACE INTO `focmm_configuration` (`key`, `value`) VALUES ('%s', '%s'), ('%s', '%s')"

In the meanwhile we prepare a new release.

MariaDB Prepared Statements, Transactions and Multi-Row Inserts

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

Also MariaDB documentation was not too verbose (here and here).

So time to do some experiments:

Uptime of a MariaDB Galera Cluster

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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?

My answer then was: "Grep the error log." My answer now is still: "Grep the error log." But slightly different:

Linux system calls of MySQL process

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 w

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