Index on FromDual GmbH

InnoDB full-text index corruption

oli.sennhauser@fromdual.com (Oli Sennhauser) — Wed, 08 Jul 2020 21:52:47 +0000

In a recent customer engagement we experienced a lot of corrupted (normal) indexes and also corrupted full-text indexes on InnoDB tables in a Galera Cluster (v10.4.13).

MariaDB indexing of NULL values

oli.sennhauser@fromdual.com (Oli Sennhauser) — Thu, 29 Nov 2018 20:10:55 +0000

In the recent MariaDB DBA advanced training class the question came up if MariaDB can make use of an index when searching for NULL values… And to be honest I was not sure any more. So instead of reading boring documentation I did some little tests:

Find evil developer habits with log_queries_not_using_indexes

oli.sennhauser@fromdual.com (Oli Sennhauser) — Wed, 20 Sep 2017 16:00:03 +0000

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

Deadlocks, indexing and Primary Key's

oli.sennhauser@fromdual.com (Oli Sennhauser) — Thu, 16 Aug 2012 10:51:40 +0000

Recently a customer has shown up with some deadlocks occurring frequently. They were of the following type (I have shortened the output a bit):

Canias optimizations

oli.sennhauser@fromdual.com (Oli Sennhauser) — Wed, 28 Dec 2011 16:02:23 +0000

Canias is a great ERP product but there is still some potential to improve it. We only focus on MyISAM/InnoDB installations of Canias v6.0.2 in this article. For other DB back-ends those recommendations might be obsolete.

Impact of indices on MySQL

oli.sennhauser@fromdual.com (Oli Sennhauser) — Fri, 31 Dec 2010 17:05:17 +0000

It is generally well known that indexes help a lot to speed up database queries (especially SELECT but also UPDATE and DELETE). It is less known, that indexes also have some disadvantages.

MySQL hints

oli.sennhauser@fromdual.com (Oli Sennhauser) — Mon, 15 Mar 2010 13:38:54 +0000

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: