Re: eliminating records not in (select id ... so SLOW?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Ivan Sergio Borgonovo <mail(at)webthatworks(dot)it>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: eliminating records not in (select id ... so SLOW?
Date: 2008-08-01 14:33:59
Message-ID: 9603.1217601239@sss.pgh.pa.us
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Ivan Sergio Borgonovo <mail(at)webthatworks(dot)it> writes:
> Well I reached 3Gb of work_mem and still I got:

> "Seq Scan on catalog_categoryitem (cost=31747.84..4019284477.13
> rows=475532 width=6)"
> " Filter: (NOT (subplan))"
> " SubPlan"
> " -> Materialize (cost=31747.84..38509.51 rows=676167 width=8)"
> " -> Seq Scan on catalog_items (cost=0.00..31071.67
> rows=676167 width=8)"

Huh. The only way I can see for that to happen is if the datatypes
involved aren't hashable. What's the datatypes of the two columns
being compared, anyway?

regards, tom lane

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