More information can be found about each of these databases (known issues,
level of support, extra configuration) in the "databases" subdirectory in
this folder.
+
+------------------------------------------------------------------------
+ Use of GROUP BY
+------------------------------------------------------------------------
+
+MySQL supports GROUP BY without checking anything in the SELECT clause.
+Other DBMSs (especially Postgres) are stricter and require that all the
+non-aggregate items in the SELECT clause appear in the GROUP BY. For
+this reason, it is highly discouraged to use SELECT * with GROUP BY
+queries.
+
format it expects things to be in. :)
+== 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