I'd like an example query, to add to https://wikitech.wikimedia.org/wiki/Help:MySQL_queries It's a generalizable question that I hit every few months.

I'd like to find all instances of a [[Mediawiki:Foo]] page that have been customized - i.e. where they have been created locally, versus just using the default strings.

E.g.1 https://en.wikipedia.org/wiki/MediaWiki:Talk has been customized on Enwiki (the default is "Discussion", per translatewiki). Whereas at Frwiki, the local override was deleted in 2007, and now they just use the default - https://fr.wikipedia.org/wiki/MediaWiki:Talk

E.g.2 https://fr.wikipedia.org/wiki/MediaWiki:Pageinfo-footer doesn't exist, but https://de.wikipedia.org/wiki/MediaWiki:Pageinfo-footer and https://en.wikipedia.org/wiki/MediaWiki:Pageinfo-footer do exist.

• (Sidenote: Intriguingly with this one, the Enwiki string is empty at translatewiki, https://translatewiki.net/w/i.php?title=Special%3ATranslations&message=Pageinfo-footer%2Fen&namespace=8 )

This kind of information might help someone to decide to collate all the good ideas that are currently only in the locally customized versions, and merge them into the (a new) default message.

(Yuvipanda, Halfak, and I, discussed this a bit, in IRC)

See also: T140585: The problem of customized local messages for links to Wikimedia tools