Re: Tsearch2 performance on big database

Oleg Bartunov wrote:
> from my notes
> http://www.sai.msu.su/~megera/oddmuse/index.cgi/Tsearch_V2_Notes
>
> It's usefull to see words statistics, for example, to check how good
> your dictionaries work or how did you configure pg_ts_cfgmap. Also, you
> may notice probable stop words relevant for your collection. Tsearch
> provides stat() function:
>
> .......................
>
> Don't hesitate to read it and if you find some bugs or know better
wording
> I'd be glad to improve my notes.
>

Thanks, but that stat() query takes way too long.. I let it run for like
4 hours and still nothing. The database I am testing tsearch2 on is also
the production database (mysql) server so I have to be careful not to
use too many resources :o

Anyway, here's my pg_ts_cfgmap now (well the relevant bits):

default_english | lhword | {en_ispell,en_stem}
default_english | lpart_hword | {en_ispell,en_stem}
default_english | lword | {en_ispell,en_stem}

Is it normal that queries for single words (or perhaps they are words
that are common) take a really long time? Like this:

ilab=# explain analyze select count(*) from books where description_fti
@@ to_tsquery('default', 'hispanic');
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------
Aggregate (cost=20369.81..20369.81 rows=1 width=0) (actual
time=261512.031..261512.031 rows=1 loops=1)
-> Index Scan using idxfti_idx on books (cost=0.00..20349.70
rows=8041 width=0) (actual time=45777.760..261509.288 rows=674 loops=1)
Index Cond: (description_fti @@ '\'hispan\''::tsquery)
Total runtime: 261518.529 ms
(4 rows)

ilab=# explain analyze select titel from books where description_fti @@
to_tsquery('default', 'buckingham & palace');
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------
Index Scan using idxfti_idx on books (cost=0.00..20349.70 rows=8041
width=57) (actual time=18992.045..48863.385 rows=185 loops=1)
Index Cond: (description_fti @@ '\'buckingham\' & \'palac\''::tsquery)
Total runtime: 48863.874 ms
(3 rows)

I dont know what happened, these queries were a lot faster 2 days
ago..what the feck is going on?!

Rick

--
Systems Administrator for Rockingstone IT
http://www.rockingstone.com
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