Re: ts_rank seems very slow (140 ranked documents / second on my machine)

Reopening a six months old discussion... Is there any plans to improve
ts_rank performance by making it able to use GIN/GIST indices?

From re-reading Oleg answers, I understand FTS indices do not contain
enough information for ts_rank. Because of that, ts_rank has to read the
ts_vector, which is stored in TOAST table, which triggers a random read for
each ranked document.

Cheers,

Nicolas Grilly

On Wed, Jul 13, 2011 at 18:55, Nicolas Grilly <nicolas(at)gardentechno(dot)com>wrote:

> The first query ran in 347 seconds; the second one in 374 seconds.
> Conclusion: There is no significant overhead in the ts_rank function
> itself. It's slow because ts_rank has to read in random order 40 000
> ts_vector stored in TOAST table. The slow execution time looks like
> a direct consequence of storing ts_vector in TOAST table...
>
> > :( The only solution I see is to store enough information for ranking
> in index.
>
> Is it the expected behavior? How can I improve that?
>