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From: panam <panam@gmx.net>
To: pgsql-hackers@postgresql.org
Subject: Re: [PERFORM] Hash Anti Join performance degradation
Date: Wed, 1 Jun 2011 05:40:55 -0700 (PDT)
Message-ID: <1306932055085-4445123.post@n5.nabble.com> (raw)
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Tom Lane-2 wrote:
> 
> It looks like it ought to be an O(N^2)
> situation, so the improvement should be noticeable but not amazing.
> 

Hm, the performance was reasonable again when doing a cluster...
So I believe this should be more a technical than an
algorithmical/complexity issue. Maybe it is the way the hashtable is built
and that order makes a difference in that case? In short: Why is clustered
data not affected?

Regards,
panam

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