Lock on FromDual GmbH

dbstat for MariaDB (and MySQL)

oli.sennhauser@fromdual.com (Oli Sennhauser) — Thu, 14 Mar 2024 15:36:57 +0000

An idea that I have been thinking about for a long time and have now, thanks to a customer, finally tackled is dbstat for MariaDB/MySQL. The idea is based on sar/sysstat by Sebastien Godard:

Upgrading MariaDB to the pre-latest minor release

oli.sennhauser@fromdual.com (Oli Sennhauser) — Wed, 08 Feb 2023 13:45:30 +0000

Scenario: MariaDB Community Server is release every 3 months. The exact date is not known but it is typically about 2 to 3 weeks after the MySQL/Oracle CPU.

MyISAM locking and who is the evil?

oli.sennhauser@fromdual.com (Oli Sennhauser) — Wed, 23 Sep 2020 09:58:35 +0000

Yes, I know, MyISAM is deprecated and unofficially discontinued by the vendors. But we still have from time to time customers using MyISAM and even evangelize for MyISAM…

MariaDB and MySQL package holding or locking

oli.sennhauser@fromdual.com (Oli Sennhauser) — Fri, 07 Aug 2020 16:02:24 +0000

Repositories from your favourite Linux distribution and from your favourite database software vendor get regular package updates. If you do periodic system upgrades (for example every 2 weeks as we do) you get the newest packages of a release series.
Unfortunately recently the software vendors started not only to fix bugs in new releases but also to introduce new features. And when you fix bugs or introduce new stuff new bugs might appear.
To avoid being hit unexpectedly by new bugs you do not want to upgrade untested software. To achieve this you want to keep/not upgrade some important packages. For example the MariaDB or MySQL server package.
This package pinning is called package version lock on CentOS and Redhat and package holding on Debian and Ubuntu.

innodb_deadlock_detect - Rather Hands off!

oli.sennhauser@fromdual.com (Oli Sennhauser) — Mon, 23 Mar 2020 11:24:15 +0000

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).

MariaDB and MySQL PERFORMANCE_SCHEMA Hints

oli.sennhauser@fromdual.com (Oli Sennhauser) — Sun, 14 Jul 2013 09:29:09 +0200

Accounts not properly closing connections
Unused indexes
Who created temporary (disk) tables
Accounts which never connected since last start-up
Users which never connected since last start-up
Totally unused accounts (never connected since last restart and not used to check Stored Program or View privileges) since last start-up
SHOW FULL PROCESSLIST
Storage Engines per schema
Tables without a Primary Key
Bad SQL queries of users
SHOW PROFILE in PERFORMANCE_SCHEMA
SELECT, INSERT, UPDATE and DELETE per table
Top long running queries
Tables never written to
DML, DDL and DCL per account
Finding syntactically wrong/erroneous MySQL queries
Finding queries served by MySQL Query Cache
Grant access to sys schema to another user
Grant access to PERFORMANCE_SCHEMA schema to another user
Find InnoDB Locks
Find Metadata Locks
What did a Connection before sleeping?
How many statements did another (sleeping) connection?
MyISAM locking
Connections per user
Connections per user and IP
Accounts which could not connect or with connection errors
Temporary tables filling my disk
Who is writing to the binary log
Average binlog transaction size
Result size of SELECT statement
Find open long running transactions

MariaDB

On MariaDB you have to enable the Performance Schema first before use: