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Re: BUG #2930: Hash join abyssmal with many null fields.

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Maciej Babinski" <maciej+postgres(at)apathy(dot)killer-robot(dot)net>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #2930: Hash join abyssmal with many null fields.
Date: 2007-01-26 05:49:52
Message-ID: 18474.1169790592@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-bugs
"Maciej Babinski" <maciej+postgres(at)apathy(dot)killer-robot(dot)net> writes:
> Hash join of columns with many null fields is very slow unless the null
> fields are commented out.

I see no bug here.  AFAICT your "much faster" query gets that way by
having eliminated all the candidate join rows on the B side.

			regards, tom lane

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Subject: Re: BUG #2930: Hash join abyssmal with many null fields.
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