On Oct 3, 2006, at 13:25 , Arnaud Lesauvage wrote:
The problem is that simple select queries with the primary key in
the WHERE statement take very long to run.
For example, this query returns only 7 rows and takes about 1
second to run !
SELECT * FROM table1 WHERE gid in (33,110,65,84,92,94,13,7,68,41);
This is a very small table, but generally speaking, such queries
benefit from an index; eg.,
create index table1_gid on table1 (gid);
Note that PostgreSQL may still perform a sequential scan if it thinks
this has a lower cost, eg. for small tables that span just a few pages.
I have run "VACUUM FULL" on this table many times... I don't know
what to try next !
PostgreSQL's query planner relies on table statistics to perform
certain optimizations; make sure you run "analyze table1".
Alexander.
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