wikimedia/mediawiki-core

This document describes the state of Postgres support in MediaWiki.

== Overview ==

Support for PostgreSQL has been available since version 1.7
of MediaWiki, and is fairly well maintained. The main code
is very well integrated, while extensions are very hit and miss.
Still, it is probably the most supported database after MySQL.
Much of the work in making MediaWiki database-agnostic came
about through the work of creating Postgres support.

== Required versions ==

The current minimum version of PostgreSQL for MediaWiki is 10.

== Database schema ==

PostgreSQL schema is automatically generated from the abstract schema.
You can see the generated schema in maintenance/postgres/tables-generated.sql

For more information on abstract schema see:
https://www.mediawiki.org/wiki/Manual:Schema_changes

== MySQL differences ==

The major differences between MySQL and Postgres are represented as
methods in the Database class. For example, implicitGroupby() is
true for MySQL and false for Postgres. This means that in those
places where the code does not add all the non-aggregate items
from the SELECT clause to the GROUP BY, we can add them in, but in
a conditional manner with the above method, as simply adding them
all in to the main query may cause performance problems with
MySQL.

== Getting help ==

In addition to the normal venues (MediaWiki mailing lists
and IRC channels), the #postgresql channel on irc.libera.chat
is a friendly and expert resource if you should encounter a
problem with your Postgres-enabled MediaWiki.