I'm using AWS CloudSearch for a search index, and the user can currently search over it for records which match the name field and a few others. However, we have users in different languages and I would like to give a boost to results which match their local language. Every record has a locale field, which could be a facet. However, I don't want to simply exclude results which don't match, and nor do I want to simply sort it so that everything in their language always comes first regardless of 'relevance' - I simply want to give a 'boost' to any result where locale=<my locale>.
In other words, I would like highly relevant matches in a different locale to still beat barely relevant matches in my own language, but relevant matches in my own language should definitely rank higher than matches in a different language.
Is there a way to do this when I query CloudSearch or should I just do the reordering client side once I have fetched all of the results?
So this was painfully convoluted but I did manage to get it to work in the end. If you are doing a structured search (q.parser=structured) then you can perform a query that receives a boost if the locale field matches a given value.
Sadly, where it gets a bit cumbersome, is that it doesn't really seem to be designed for boosting things that match something other than your main query, so by default it filters out anything that doesn't match the locale and excludes them entirely from the results. So you have to combine two versions of the query with an (or) - one with the boost and one without.
So my basic query (which in my case was already (or 'un' (prefix 'un'))) now becomes (or (and <OLD_QUERY> (term field=locale boost=2.5 'en')) <OLD_QUERY>)
In other words: EITHER a match for the original query where locale='en', boosted by 2.5, OR a match for that same query in any locale without a boost.
Painful, but it works!