From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | sthomas(at)cise(dot)ufl(dot)edu (Shiby Thomas) |
Cc: | scrappy(at)hub(dot)org, pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Re: [HACKERS] postgres performance |
Date: | 1998-01-16 00:26:45 |
Message-ID: | 199801160026.TAA22111@candle.pha.pa.us |
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Lists: | pgsql-hackers |
>
>
> => There may be optimizations in the 2.6 libraries that would improve
> => performance, but I wouldn't suspect that it would make *that* big of a
> => difference. What is your SQL/join statemnt? How are you running
> => postmaster? What does 'explain' show?
> =>
> The complete query is this:
>
> select item1, item2, count(t1.tid) into table f2_temp from data t1, data t2,
> c2
> where t1.item = c2.item1 and t2.item = c2.item2 and t1.tid = t2.tid group by
> ite
> m1, item2
>
> data is a table with 2 integer columns (tid, item) and it has ~300K records
> c2 is a table (item1, item2), both integers and has ~1.5K records.
>
> I was directly running postgres with the -B and -S flags to give more buffers
> and sortMem. I also tried several join plans by the -f flags. Hash join works
> the best and that itself is too slow (perhaps due to the self join)
>
I have a possible workaround. Turn GEQO on:
SET GEQO ON=1
and try it. Let us know.
--
Bruce Momjian
maillist(at)candle(dot)pha(dot)pa(dot)us
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