Null on FromDual GmbH

To NULL, or not to NULL, that is the question!

oli.sennhauser@fromdual.com (Oli Sennhauser) — Fri, 14 Dec 2018 08:33:25 +0000

As we already stated in earlier articles in this blog
[1 and 2
] it is a good idea to use NULL values properly in MariaDB and MySQL.

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:

Using NULL as default values

oli.sennhauser@fromdual.com (Oli Sennhauser) — Thu, 21 Jul 2011 18:35:34 +0000

Abstract:

It is common practice in MySQL table design that fields are declared as NOT NULL but some non-sense DEFAULT values are specified for unknown field contents. In this article we show why this behavior is non optimal an why you should better declare a field to allow NULL values and use NULL values instead of some dummy values.

How much space does NULL need?

oli.sennhauser@fromdual.com (Oli Sennhauser) — Sun, 08 Feb 2026 16:15:00 +0100

The last time I consulted a customer, he came up to me beaming with joy and said that he had taken my advice and changed all the primary key columns from BIGINT (8 bytes) to INT (4 bytes) and that had made a big difference! His MySQL 8.4 database is now 750 Gbyte smaller (from 5.5 Tbyte). Nice!