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From: Ian Westmacott <ianw@intellivid.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: Why hash join instead of nested loop?
Date: Tue, 09 Aug 2005 08:15:56 -0400
Message-ID: <1123589756.15206.4.camel@spectre.intellivid.com> (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, 2005-08-08 at 20:58, Tom Lane wrote:
> I'd be interested to see results from other people using 7.4.* too.

7.4.8:
                                                                    
QUERY
PLAN                                                                    
----------------------------------------------------------------------------------------------------------------------------------------------------
 Hash Join  (cost=4.83..5.91 rows=1 width=14) (actual time=0.122..0.126
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=0.003..0.006 rows=5 loops=1)
   ->  Hash  (cost=4.83..4.83 rows=1 width=4) (actual time=0.021..0.021
rows=0 loops=1)
         ->  Index Scan using connection_regid_obj1_index on connection 
(cost=0.00..4.83 rows=1 width=4) (actual time=0.013..0.015 rows=1
loops=1)
               Index Cond: ((connection_registry_id = 40105) AND (obj1 =
73582))
 Total runtime: 0.198 ms

7.4.2:

                                                                    
QUERY
PLAN                                                                    
----------------------------------------------------------------------------------------------------------------------------------------------------
 Hash Join  (cost=4.83..5.91 rows=1 width=14) (actual time=0.577..0.600
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=0.006..0.023 rows=5 loops=1)
   ->  Hash  (cost=4.83..4.83 rows=1 width=4) (actual time=0.032..0.032
rows=0 loops=1)
         ->  Index Scan using connection_regid_obj1_index on connection 
(cost=0.00..4.83 rows=1 width=4) (actual time=0.016..0.020 rows=1
loops=1)
               Index Cond: ((connection_registry_id = 40105) AND (obj1 =
73582))
 Total runtime: 0.697 ms


	--Ian





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  Subject: Re: Why hash join instead of nested loop?
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