Re: Very bad FTS performance with the Polish config

On Wed, 18 Nov 2009, Wojciech Knapik wrote:

>
>> your polish_english, polish configurations uses ispell language and slow,
>> while english configuration doesn't contains ispell. So, what's your
>> complains ? Try add ispell dictionary to english configuration and see
>> timings.
>
> Oh, so this is not anomalous ? These are the expected speeds for an ispell
> dictionary ? I didn't realize that. Sorry for the bother then. It just seemed
> way too slow to be practical.

You can see real timings using ts_lexize() function for different dictionaries
(try several time to avoid cold-start problem) instead of ts_headline(),
which involves other factors.

On my test machine I see no real difference between very simple dictionary
and french ispell, snowball dictionaries:

dev-oleg=# select ts_lexize('simple','voila');
ts_lexize
-----------
{voila}
(1 row)

Time: 0.282 ms
dev-oleg=# select ts_lexize('simple','voila');
ts_lexize
-----------
{voila}
(1 row)

Time: 0.269 ms

dev-oleg=# select ts_lexize('french_stem','voila');
ts_lexize
-----------
{voil}
(1 row)

Time: 0.187 ms

I see no big difference in ts_headline as well:

dev-oleg=# select ts_headline('english','I can do voila', 'voila'::tsquery);
ts_headline
-----------------------
I can do <b>voila</b>
(1 row)

Time: 0.265 ms
dev-oleg=# select ts_headline('nomaofr','I can do voila', 'voila'::tsquery);
ts_headline
-----------------------
I can do <b>voila</b>
(1 row)

Time: 0.299 ms

This is 8.4.1 version of PostgreSQL.

Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83