This works on the special page prefixindex [[:de:Special:PrefixIndex/Kategorie:Vorlage:I]], but fails on the openSearchXML-Api with the namespace:
action=opensearch&format=xml&namespace=14&search=Vorlage:I

Changing to MWSearch, because it looks like a problem there or in LuceneSearch.

MWSearch implements Hook "PrefixSearchBackend" and return false, so override the default from MediaWiki, which work.

Renaming and moving bug.

Steps to reproduce:

• Get a wiki with pages like "Category:Template:Foo" (namespace=14, title="Template:Foo")
• Query open search namespace=14&prefix=Template:F
• ApiOpenSearch detects "Template:" as a prefix and searches in that namespace, ignoring 14.

Source code to confirm:

• ApiOpenSearch calls PrefixSearch [1]
• PrefixSearch creates a Title object from search query, and calls getNamespace(). If it does not return NS_MAIN, it uses the namespace of that title object, thus overriding and ignoring the given namespace id to search in (line 29 of PrefixSearch.php)

See also bug 30323.

Krinkle

[1] http://svn.wikimedia.org/viewvc/mediawiki/trunk/phase3/includes/api/ApiOpenSearch.php?revision=92400&view=markup#l45
[2] http://svn.wikimedia.org/viewvc/mediawiki/trunk/phase3/includes/PrefixSearch.php?revision=86255&view=markup#l24

Just brought this up on IRC. Seems it's not possible due to performance to query multiple namespaces in the same query because the index is on page_namespace,page_title. So that would mean that searching for "Foo" in namespace 0, 5 and 10 would likely only give results for the namespace 0 since it's ordered by namespace and then by page_title.

For it to make sense we'd have to do multiple queries (one for each of the wanted namespaces). Then in PHP combine them and sort them by page_title and then by namespacename (not namespace-id).

So prefix "Foo", with namespaces=0|2|4 would give:
['Foo', 'Abbawiki:Foo', 'User:Foobar']

switch to milestone, remove release tracking dep

no work done and release is coming