Re: GIN improvements part2: fast scan

On Mon, Feb 3, 2014 at 8:19 PM, Tomas Vondra <tv(at)fuzzy(dot)cz> wrote:

> > > Sometimes test cases are not what we expect. For example:
> >> >
> >> > =# explain SELECT id FROM messages WHERE body_tsvector @@
> >> > to_tsquery('english','(5alpha1-initdb''d)');
> >> > QUERY PLAN
> >> >
> >> >
> >>
> ────────────────────────────────────────────────────────────────────────────────
> >> > Bitmap Heap Scan on messages (cost=84.00..88.01 rows=1 width=4)
> >> > Recheck Cond: (body_tsvector @@ '''5alpha1-initdb'' & ''5alpha1'' &
> >> > ''initdb'' & ''d'''::tsquery)
> >> > -> Bitmap Index Scan on messages_body_tsvector_idx
> >> (cost=0.00..84.00
> >> > rows=1 width=0)
> >> > Index Cond: (body_tsvector @@ '''5alpha1-initdb'' &
> >> ''5alpha1''
> >> &
> >> > ''initdb'' & ''d'''::tsquery)
> >> > Planning time: 0.257 ms
> >> > (5 rows)
> >> >
> >> > 5alpha1-initdb'd is 3 gin entries with different frequencies.
> >>
> >> Why do you find that strange? The way the query is formed or the way
> >> it's
> >> evaluated?
> >>
> >> The query generator certainly is not perfect, so it may produce some
> >> strange queries.
> >>
> >
> > I just mean that in this case 3 words doesn't mean 3 gin entries.
>
> Isn't that expected? I mean, that's what to_tsquery may do, right?
>

Everything is absolutely correct. :-) It just may be not what do you expect
if you aren't getting into details.

------
With best regards,
Alexander Korotkov.