If you have a foreign key on a column, then whenever the primary key is
modified, the following checks may occur:
* Check to see if the child row exists (no action)
* Delete the child row (cascade delete)
* Update the child row (cascade update)
All of which will benefit from an index...
Chris
> -----Original Message-----
> From: Bruce Momjian [mailto:pgman@candle.pha.pa.us]
> Sent: Friday, 21 December 2001 11:59 AM
> To: Christopher Kings-Lynne
> Cc: Hackers
> Subject: Re: [HACKERS] contrib idea
>
>
> > Hi All,
> >
> > You know how when you create a foreign key in postgres it isn't
> > automatically indexed, and it seems to me that it's very useful to have
> > indexed foreign keys, especially if you use lots of them.
> >
> > So, how about a 'findslowfks' contrib? This would basically be
> similar to
> > Bruce's findoidjoins thingy...
>
> Why would you want an index on a foreign key. Primary I can understand,
> but is there use to foreignt? Is it for checking of changes to primary
> keys?
>
> --
> Bruce Momjian | http://candle.pha.pa.us
> pgman@candle.pha.pa.us | (610) 853-3000
> + If your life is a hard drive, | 830 Blythe Avenue
> + Christ can be your backup. | Drexel Hill, Pennsylvania 19026
>