After extensive testing over the last several months using a new search query scoring method called BM25 (Best Matching) [1], we recently completed a limited production release to the following top languages: English, German, Spanish, Russian, Portuguese, French, Italian, Polish, Dutch and Arabic. This new release is replacing the older search method called tf-idf (term frequency-inverse document frequency) [2].
We have additional testing to do [3,4] to figure out if BM25 will work in languages that don’t use spaces in-between their words , i.e.: Japanese, Chinese, etc.
The Discovery team announces much of our completed work in weekly status updates [5 , 6 ], but some of the work isn’t actually obvious to anyone who uses our search engine - t hat is because it isn’t actually ‘live’ until a complete re-index of the servers occur. We’ve created a recurring ticket in Phabricator [ 7 ] to keep track of the work that goes live in production after a re-index, such as the one we’ve also just completed. A few highlights of the recent re-index are implementing ascii-folding for the French language and fixing several bugs for French ÿ, and Russian ’Е’ and 'Ё' when those characters are entered in a search query.
Cheers from the Discovery Search Team!
[1] https://en.wikipedia.org/wiki/Okapi_BM25 [2] https://en.wikipedia.org/wiki/Tf%E2%80%93idf [3] https://phabricator.wikimedia.org/T147495 [4] https://phabricator.wikimedia.org/T147501 [5] https://www.mediawiki.org/wiki/Wikimedia_Discovery#Updates%E2%80%8B [ 6 ] https://www.mediawiki.org/wiki/Discovery/Status_updates [ 7 ] https://phabricator.wikimedia.org/T147505
-- deb tankersley Product Manager, Discovery irc: debt Wikimedia Foundation