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

[Nicolas Grilly <nicolas@xxxxxxxxxxxxxxxx>]

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@xxxxxxxxxxxxxxxx> 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?