It appears that a new Ukrainian analyzer should come out with Lucene 6.2:
https://github.com/elastic/elasticsearch/issues/19433
When Lucene 6.2 is released, we should check that the Ukrainian analyzer is present, and once we've updated our version of Elasticsearch and Lucene, we should then enable it for Ukrainian wikis (replacing the current Russian analyzer that is used instead)
ElasticSearch 5.1.1 is out!
Now with proper Ukrainian analyzer: https://www.elastic.co/guide/en/elasticsearch/reference/5.1/release-notes-5.1.1.html#feature-5.1.1
@Dchaplinsky —thanks for the alert! Upgrading to Elastic 5 is one of our goals for next quarter, and I'll be keeping an eye out for newly available language analyzers.
The Ukrainian Analyzer is available for ES 5+, and I'll be testing it (T160106) along with any other promising candidates I find (T160105) .
I suggest closing this issue, since we've tracked it, noted that it's ready (thanks, @Dchaplinsky!), and we're looking at it now.