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Re: How do FKs work?

From: "Marc G(dot) Fournier" <scrappy(at)postgresql(dot)org>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: How do FKs work?
Date: 2004-10-10 00:43:50
Message-ID: (view raw or whole thread)
Lists: pgsql-sql
On Sat, 9 Oct 2004, Tom Lane wrote:

> "Marc G. Fournier" <scrappy(at)hub(dot)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 (
Email: scrappy(at)hub(dot)org           Yahoo!: yscrappy              ICQ: 7615664

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