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SemanticMediaWiki is a MediaWiki extension.

Status for Mediawiki4Intranet distribution:

  • Inclusion date: 2012-12-12
  • Included version: 2.3.x
  • Improvement status: Forked in MediaWiki4Intranet with major improvements

Usage note

It seems almost nobody uses SMW for its original ideas (semantic web, rdf, ontologies and etc) — everyone just uses it to be able to add properties to pages, create something like «object model», create Semantic Forms, use #ask queries as something like «sql» for objects and turn MediaWiki into a CMS.

But SMW is far from ideal for this purpose — it’s not that fast, properties are global (i.e. not specific to an object class), and the #ask query language is not so convenient… Usually it ends up with a massive amount of very ugly «Wiki-programming» efforts.

So, avoid massive usage of SMW if you can. If you still have to use it, check our improvements to it (see below).

Our improvements

  • Query optimizer: identical subqueries are executed only once (for example, in <q>a OR b</q> <q>c OR d <q>a OR b</q></q> the «a OR b» part will be executed only once), identical terms are removed from conjunctions/disjunctions («a AND a», «a OR a» == just a)
  • Conjunction-of-disjunctions execution bug fixed: in the original SMW, «(a OR b) AND (c OR d)» query was not executed at all! (test case: {{#ask: <q>[[A::B]] OR [[C::D]]</q> <q>[[E::F]] OR [[G::H]]</q> | format=debug }}). Patch sent to github:
  • Negation operator support: syntax is {{#ask: [[prop::val]] !<q>...subquery...</q> }} or just {{#ask: [[prop::val]] ![[prop2::val2]] }}. Patch sent to github:
  • Disable forced type-named properties: in the original SMW, data type aliases also have an unpleasant side-effect: if a property name matches the alias of some data type (for example «Telephone number») — the property will have that data type forced and you cannot override it. Patch sent to github:
  • Automatic refresh of all pages with semantic queries on any property update — in the original SMW you have to manually refresh it every time. Of course this can lead to frequent cache flushes — even the queries that don’t use the updated property are flushed — but at least the user always gets correct query results.

Rough estimate for getting all this in trunk: never, or not any time soon. You have to push authors very hard to be able to submit something in SMW. I don’t feel that I want to spend my time on it.