http://developer.postgresql.org/pgdocs/postgres/textsearch-controls.html
Ranking Search Results
shows and example which says
"This is the same example using normalized ranking"
and then gives a query which calculates normalization in an incorrect
manner, yet without using the normalization parameter. A correct example
would be something like this:
SELECT title, ts_rank_cd(textsearch, query, 8 /*Normalization*/) AS rank
FROM apod, to_tsquery('neutrino|(dark & matter)') query
WHERE query @@ textsearch
ORDER BY rank DESC LIMIT 10;
I can't rerun the query because I don't have the example data set used.
Is that available?
This section also describes the two ranking functions supplied and
suggests you can write your own also.
- Can we say what the differences are between the two ranking functions?
Why do we have two?
- Can we supply or link to an example ranking function to allow people
to write their own?
--
Simon Riggs
2ndQuadrant http://www.2ndQuadrant.com