From: Marc G. Fournier <scrappy@postgresql.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-sql@postgresql.org
Subject: Re: How do FKs work?
Date: Sat, 9 Oct 2004 21:43:50 -0300 (ADT)
Message-ID: <20041009214318.V54093@ganymede.hub.org> (raw)
In-Reply-To: <6093.1097367833@sss.pgh.pa.us>
References: <20041009145332.D54093@ganymede.hub.org>
<6093.1097367833@sss.pgh.pa.us>
On Sat, 9 Oct 2004, Tom Lane wrote:
> "Marc G. Fournier" <scrappy@hub.org> writes:
>> Have a table with two FKs on it ... 2 different fields in the table point
>> to the same field in another table ...
>
>> When I do an 'EXPLAIN ANALYZE DELETE FROM table WHERE field = #;', it
>> never comes back ... or, at lesat, takes a *very* long time ...
>
> Do you have indexes on the referencing columns? Are they exactly the
> same datatype as the referenced column? You can get really awful plans
> for the FK-checking queries if not.
Yup, that was my first thought ... running SELECT's joining the two tables
on the FK fields shows indices being used, and fast times ...
----
Marc G. Fournier Hub.Org Networking Services (http://www.hub.org)
Email: scrappy@hub.org Yahoo!: yscrappy ICQ: 7615664
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To: pgsql-sql@postgresql.org
Cc: scrappy@postgresql.org, tgl@sss.pgh.pa.us
Subject: Re: How do FKs work?
In-Reply-To: <20041009214318.V54093@ganymede.hub.org>
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