On Sat, Feb 18, 2012 at 12:39, Andrey Chursin <andll@danasoft.ws> wrote:
Hello
I have two unrelated questions about fts function ts_rank:
1) I've created GiST index on column with fts vector, but query SELECT * FROM table ORDER BY ts_rank(field, :query) LIMIT 20 is perfomed with sequential table scan. Index was created on field column. Does it mean FTS indexes does not support order by ranking? Or I need somehow to create separated index for ranking?
2) I have a misunderstanding with proximity ranking work. Given two vectors 'a:1 b:2' and 'a:1 b:1000', i am measuring ts_rank(vector, 'a' | 'b'). And it is equal! But when i am replacing query with & operator, e.g. asking for ts_rank(vector, 'a' & 'b') i am getting different numbers. Why do I get proximity ranking only for AND fts queries? This is a problem as far as to_tsquery produces OR queries, so i need self-written postprocessing of query to replace OR with AND. -- Regards, Andrey
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