From: Tom Lane <tgl@sss.pgh.pa.us>
To: Florian Weimer <fweimer@bfk.de>
Cc: pgsql-performance@postgresql.org
Subject: Re: Abysmal hash join
Date: Mon, 11 Sep 2006 10:28:51 -0400
Message-ID: <22641.1157984931@sss.pgh.pa.us> (raw)
In-Reply-To: <821wqiy0oc.fsf@mid.bfk.de>
References: <821wqiy0oc.fsf@mid.bfk.de>
Florian Weimer <fweimer@bfk.de> writes:
> -> Bitmap Index Scan on large_rel_1_field_1 (cost=0.00..2003.09 rows=193739 width=0) (actual time=0.148..0.148 rows=12 loops=1)
> Index Cond: (n.field_1 = "outer".field_2)
What you need to look into is why that rowcount estimate is off by four
orders of magnitude.
The estimate on the smaller table is only off by a factor of 75 but
that's still pretty darn awful. Are the statistics up to date? Maybe
larger stats targets would help.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, fweimer@bfk.de
Subject: Re: Abysmal hash join
In-Reply-To: <22641.1157984931@sss.pgh.pa.us>
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