Rank based on the number of matching OR fields?

Le 2012-09-25 à 14:16, W. Matthew Wilson a écrit :

I want to run a query like to_tsquery("A | B | C") and then rank the
results so that if a document contained A, B, and C, then it would
rank above a document that just had some subset.

How would I do such a thing?

http://www.postgresql.org/docs/current/static/textsearch-controls.html#TEXTSEARCH-RANKING

Hope that helps,
François Beausoleil

If you're easily able to do it, (i.e. you're building rather than receiving
the query), you could rank them by the conjunction of the search terms
first:

ORDER BY ts_rank(vector, to_tsquery('A & B & C')) desc, ts_rank(vector,
to_tsquery('A | B | C')) desc

Or just explicitly order by whether the conjunction matches:

ORDER BY case when to_tsquery('A & B & C') @@ vector then 0 else 1
end, ts_rank(vector, to_tsquery('A | B | C')) desc

I think either of these would have the property you want, but I don't know
how they would otherwise affect the quality of the ranking. You should set
up a test group of documents and make sure your mechanism ranks that group
properly on test queries.

Joel

On Tue, Sep 25, 2012 at 11:16 AM, W. Matthew Wilson <matt@tplus1.com> wrote: