IgnoreCase

Redirect or disambiguate titles that case-insensitively match existing ones.

Mechanism

• When exactly one case variation of a title exists, all alternate casings will be redirected to that title as if a #REDIRECT existed there (including a "Redirected from" message).
• When more than one case variation exists, or when ?redirect=no applies, they are listed before the normal missing article text.
• When no such title exists in any case, the normal missing article text is displayed as usual.

Comparison with SaneCase

Property	SaneCase	IgnoreCase
Redirection mechanism	Raw PHP header( 'HTTP/1.1 301 Moved Permanently' )	Existing MediaWiki #REDIRECT infrastructure
Behavior with multiple existing case variations	Redirect to the one which the database arbitrarily returns first	List variations in missing article message
Extra queries per existing article	Zero	Zero
Extra queries per missing article	One select from page + one Title::newFromID() call	One select from page

Notes

• In both SaneCase and IgnoreCase, one query is required to find the existing case variation. However, SaneCase uses Title::newFromID(), which could cause an extra query, in order to then ->getLocalURL().
• SaneCase avoids extra queries for existing articles by only using the BeforeDisplayNoArticleText hook, which is only triggered when the article's existence has already been checked. IgnoreCase avoids extra queries for existing articles by using WikiPage::exists() which makes no extra queries.
• The "existing MediaWiki #REDIRECT infrastructure" in question calls the InitializeArticleMaybeRedirect hook, which is what IgnoreCase uses.