From: Tom Lane <tgl@sss.pgh.pa.us>
To: Harry Hehl <Harry.Hehl@diskstream.com>
Cc: Mark Kirkwood <markir@paradise.net.nz>
Cc: pgsql-performance@postgresql.org
Subject: Re: Sequencial scan instead of using index
Date: Tue, 11 Apr 2006 18:49:59 -0400
Message-ID: <11754.1144795799@sss.pgh.pa.us> (raw)
In-Reply-To: <6AD4F3A63B017C4FB074E2C895AD18541090C6@EXCHSRV.waterloonetworking.net>
References: <6AD4F3A63B017C4FB074E2C895AD18541090C6@EXCHSRV.waterloonetworking.net>
"Harry Hehl" <Harry.Hehl@diskstream.com> writes:
> Nested Loop IN Join (cost=21432.32..951981.42 rows=204910 width=217)
> Join Filter: ("outer".objectid = "inner".ref_oid)
> -> Append (cost=0.00..8454.10 rows=204910 width=217)
> -> Seq Scan on omfile (cost=0.00..8428.20 rows=204320
> width=217)
> -> Seq Scan on omimagefile omfile (cost=0.00..12.70 rows=270
> width=217)
> -> Seq Scan on omclipfile omfile (cost=0.00..13.20 rows=320
> width=217)
> -> Materialize (cost=21432.32..21434.32 rows=200 width=16)
> -> Unique (cost=20614.91..21430.12 rows=200 width=16)
> -> Sort (cost=20614.91..21022.52 rows=163041 width=16)
> Sort Key: ts.ref_oid
> -> Seq Scan on ts (cost=0.00..3739.41 rows=163041
> width=16)
> (11 rows)
> Time: 164.232 ms
> So how can I get index scans to work consistently with joins?
It's not the join that's the problem, it's the inheritance. I recently
improved the planner so that it can consider appended indexscans for an
inheritance tree on the inside of a join, but no pre-8.2 release can do
it.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, Harry.Hehl@diskstream.com, markir@paradise.net.nz
Subject: Re: Sequencial scan instead of using index
In-Reply-To: <11754.1144795799@sss.pgh.pa.us>
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