| 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: | 20041009214318.V54093@ganymede.hub.org |
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| 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 (http://www.hub.org)
Email: scrappy(at)hub(dot)org Yahoo!: yscrappy ICQ: 7615664
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