On Sat, 8 Mar 2008, Jan Urbaski wrote:
Unfortunately, selectivity estimation for query is much difficult than just
estimate frequency of individual word.
Sure, given something like 'cats & dogs'::tsquery the frequency of 'cat' and
'dog' won't suffice. But at least it's a starting point and if we estimate
that 80% of the documents have 'dog' and 70% have 'cat' then we can tell for
sure that at least 50% have both and that's a lot better than 0.1% that's
being returned now.
certainly yes and given that most popular queries are single word query
this would very helpful in most cases.
The reason I though about ts_stat() improvement is that we could use its
statistics for incomplete search feature people requested, when
AND query like ( a & b &c ) rewrites to a set of AND|OR queries depending
on the terms occurency.
Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: [EMAIL PROTECTED], http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83
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