It should be better in 9.1
http://archives.postgresql.org/message-id/4c2ddc9b.1060...@sigaev.ru
Oleg
On Wed, 27 Apr 2011, Mark wrote:
I have problem with GIN index. Queries over it takes a lot of time. Some
informations:
I've got a table with tsvector- textvector:
CREATE TABLE mediawiki.pagecontent
(
old_id integer NOT NULL DEFAULT
nextval('mediawiki.text_old_id_seq'::regclass),
old_text text,
old_flags text,
textvector tsvector,
CONSTRAINT pagecontent_pkey PRIMARY KEY (old_id)
)
The table has about 311 000 rows.
I've created GIN index over textvector:
CREATE INDEX gin_index2 ON mediawiki.pagecontent USING gin (textvector);
At first all was ok, but last days I find out that the queries take a lot of
time (10sec and more). When I start EXPLAIN ANALIZE of the query
SELECT old_id FROM mediawiki.pagecontent WHERE (textvector @@
(to_tsquery('den')))
the result is this:
"Bitmap Heap Scan on pagecontent (cost=8677.26..26663.01 rows=9037 width=4)
(actual time=8.258..8131.677 rows=9093 loops=1)"
" Recheck Cond: (textvector @@ to_tsquery('den'::text))"
" -> Bitmap Index Scan on gin_index2 (cost=0.00..8675.00 rows=9037
width=0) (actual time=6.002..6.002 rows=9093 loops=1)"
" Index Cond: (textvector @@ to_tsquery('den'::text))"
"Total runtime: 8150.949 ms"
It seems that the GIN index was not used. At first I though, that there is
some mess in the db, cause I provided some experiments(delete and import
data and GIN index), so I used vacuum, afterwards I tried pg_dump and
pg_restore, but it did not help.
Could you please point me in the right direction, where could be the
problem?
Thanks a lot
Mark
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Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: o...@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83
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