On Fri, Jan 24, 2014 at 6:48 AM, Tomas Vondra <tv@fuzzy.cz> wrote:
I plan to do more thorough testing over the weekend, but I'd like to
make sure I understand what to expect. My understanding is that this patch should:
- give the same results as the current code (e.g. the fulltext should not return different rows / change the ts_rank etc.)
- improve the performance of fulltext queries
Are there any obvious rules what queries will benefit most from this? The queries generated by the tool I'm using for testing are mostly of this form:
SELECT id FROM messages WHERE body_tsvector @ plainto_tsquery('english', 'word1 word2 ...') ORDER BY ts_rank(...) DESC LIMIT :n;
with varying number of words and LIMIT values. During the testing today I haven't noticed any obvious performance difference, but I haven't spent much time on that.
These patches optimizes only query with multiple WHERE clauses. For instance:
SELECT id FROM messages WHERE body_tsvector @ plainto_tsquery('english', 'word1') AND body_tsvector @ plainto_tsquery('english', 'word2') ORDER BY ts_rank(...) DESC LIMIT :n;
Optimizations inside single clause will be provided as separate patch.
