Litao,
> I have some tables and there are almost only
> inserts. So I do not care about the "dead tuples",
> but do care about the statistics.
Then just run ANALYZE on those tables, and not VACUUM.
ANALYZE <table-name>;
> My PG version is 7.3.2.
I would suggest upgrading to 7.3.6; the version you are using has several
known bugs.
--
-Josh Berkus
Aglio Database Solutions
San Francisco