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InnoDB Deadlock on SELECT? Not possible! Or Is It?

oli.sennhauser@fromdual.com (Oli Sennhauser) — Sat, 25 Nov 2023 16:58:41 +0000

Translated by deepl.com

Introduction

Two points in advance:

A deadlock is a state in which two different transactions are no longer able to continue working because each transaction holds a lock that the other transaction would need. Because both transactions are now waiting for the other transaction to release their locks, neither transaction will release their respective locks. And that would last forever. To avoid this, the MariaDB instance intervenes and kills the transaction that has done less work. The application then receives a deadlock error message of this type:

Avoid temporary disk tables with MySQL

oli.sennhauser@fromdual.com (Oli Sennhauser) — Fri, 19 Dec 2014 07:38:16 +0000

For processing SELECT queries MySQL needs some times the help of temporary tables. These temporary tables can be created either in memory or on disk.

Change MyISAM tables to InnoDB and handle SELECT COUNT(*) situation

oli.sennhauser@fromdual.com (Oli Sennhauser) — Tue, 12 Jun 2012 20:48:38 +0000

Its a known problem that changing the Storage Engine from MyISAM to InnoDB can cause some problems
[ 1
] if you have queries of this type:

Dumping BLOB's from the MySQL database

oli.sennhauser@fromdual.com (Oli Sennhauser) — Fri, 22 Apr 2011 13:52:42 +0000

A customer who is handling digital certificates had a problem with one of those. So we had to investigate.