From: Michael Fuhr <mike@fuhr.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Rhett Garber <rhettg@gmail.com>
Cc: Havasvölgyi Ottó <h.otto@freemail.hu>
Cc: pgsql-performance@postgresql.org
Subject: Re: Why hash join instead of nested loop?
Date: Mon, 8 Aug 2005 23:11:48 -0600
Message-ID: <20050809051148.GA85494@winnie.fuhr.org> (raw)
In-Reply-To: <10930.1123549106@sss.pgh.pa.us>
References: <41b0fe890508051135712a086b@mail.gmail.com>
<001801c59a0a$f4be7480$9a00a8c0@OTTO>
<41b0fe8905080516164464e04f@mail.gmail.com>
<15425.1123304631@sss.pgh.pa.us>
<41b0fe89050808100021a2a4fc@mail.gmail.com>
<10930.1123549106@sss.pgh.pa.us>
On Mon, Aug 08, 2005 at 08:58:26PM -0400, Tom Lane wrote:
> I'd be interested to see results from other people using 7.4.* too.
I just built 7.4.1 on FreeBSD 4.11-STABLE and ran your test:
test=# explain analyze select rtmessagestate.* from rtmessagestate,connection where (connection_registry_id = 40105) AND (obj1 = 73582) and id = obj2;
QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------------------------
Hash Join (cost=4.83..5.91 rows=1 width=14) (actual time=0.220..0.264 rows=1 loops=1)
Hash Cond: ("outer".id = "inner".obj2)
-> Seq Scan on rtmessagestate (cost=0.00..1.05 rows=5 width=14) (actual time=0.015..0.050 rows=5 loops=1)
-> Hash (cost=4.83..4.83 rows=1 width=4) (actual time=0.103..0.103 rows=0 loops=1)
-> Index Scan using connection_regid_obj1_index on connection (cost=0.00..4.83 rows=1 width=4) (actual time=0.070..0.081 rows=1 loops=1)
Index Cond: ((connection_registry_id = 40105) AND (obj1 = 73582))
Total runtime: 0.495 ms
(7 rows)
--
Michael Fuhr
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To: pgsql-performance@postgresql.org
Cc: mike@fuhr.org, tgl@sss.pgh.pa.us, rhettg@gmail.com, h.otto@freemail.hu
Subject: Re: Why hash join instead of nested loop?
In-Reply-To: <20050809051148.GA85494@winnie.fuhr.org>
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