Now that we've done extensive testing on the new query scoring method called BM25, we want to do an initial and limited release into production. We'll be doing this release for the top 10 languages as follows:
- English, German, Spanish, Russian, Portuguese, French, Italian, Polish, Dutch, Arabic
We are purposely not releasing BM25 onto wikis that don't have spaces between words (such as Chinese, Japanese, Thai and Khmer for starters). We have tickets to investigate how best to utilize BM25 on those types of languages that don't have spaces between words: T147495 and T147501
Plan to enable BM25 on these wikis:
- [config] Disable BM25 A/B test on enwiki and prepare an A/B test for ja, zh and th: patch
- [cirrus] Add support for routing completion queries to a specific cluster: patch
- [config] Add new vars in InititliazeSettings.php for BM25 but only activate the SimilarityConfig for these wikis: patch
- [maint] Reindex codfw with BM25
- [config] Switch default cluster to codfw for these wikis and keep completion queries to eqiad: patch
- [maint] Reindex eqiad with BM25
- [config] Switch back default cluster to eqiad for these wikis: patch