From: Emi Lu <emilu@encs.concordia.ca>
To: PostgreSQL SQL List <pgsql-sql@postgresql.org>
Subject: left join where not null vs. inner join
Date: Fri, 22 May 2009 16:51:59 -0400
Message-ID: <4A17106F.7040302@encs.concordia.ca> (raw)
Two tables, each contains more than hundreds of thousands records. Is
there any efficiency differences between (1) and (2)?
(1) T1 inner join T2 using (c1, c2)
(2) T1 left join T2 using (c1, c2) where c2 is not null
Thanks,
--
Lu Ying
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To: pgsql-sql@postgresql.org
Cc: emilu@encs.concordia.ca
Subject: Re: left join where not null vs. inner join
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