From: Tom Lane <tgl@sss.pgh.pa.us>
To: Laurenz Albe <laurenz.albe@cybertec.at>
cc: Jacque Edmund <jacqueedmund@gmail.com>, pgsql-admin@lists.postgresql.org
Subject: Re: Native Foreign Keys housekeeping time intensive for Relational
 Model
In-reply-to: <fb45b9f1134ad17b944eb073ac8523f37f4199a9.camel@cybertec.at>
References: 
 <CANOmo02GKKLsGbszLtAzLLX--Ab6d-9Bp51bYDC3dfRhe8dgvA@mail.gmail.com>
 <fb45b9f1134ad17b944eb073ac8523f37f4199a9.camel@cybertec.at>
Comments: In-reply-to Laurenz Albe <laurenz.albe@cybertec.at>
	message dated "Sat, 27 Mar 2021 11:24:30 +0100"
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Date: Sat, 27 Mar 2021 10:43:21 -0400
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Laurenz Albe <laurenz.albe@cybertec.at> writes:
> On Fri, 2021-03-26 at 14:00 -0400, Jacque Edmund wrote:
>> I've already seen that my current set of FK relationships between < 100=
 tables and data footprint
>> has yielded very large lookup times for the underlying referential inte=
grity of the FKs to vet
>> whether it can DELETE a row or not based on its FK relationships.

> I would be surprised if correctly indexed foreign keys would slow delete=
s down so that
> the performance becomes intolerable.

Deletes being slow often means that you don't have an index on the
referencing column(s).  PG requires you to have an index on the referenced
columns, but not on the other side of the FK relationship.

			regards, tom lane