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Re: Res: Finding all tables that have foreign keys referencing a table

From: Andreas Joseph Krogh <andreak(at)officenet(dot)no>
To: pgsql-sql(at)postgresql(dot)org
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, paulo matadr <saddoness(at)yahoo(dot)com(dot)br>
Subject: Re: Res: Finding all tables that have foreign keys referencing a table
Date: 2008-11-07 20:34:44
Message-ID: 200811072134.44750.andreak@officenet.no (view raw or flat)
Thread:
Lists: pgsql-sql
On Friday 07 November 2008 21:09:33 Tom Lane wrote:
> Andreas Joseph Krogh <andreak(at)officenet(dot)no> writes:
> > AFAICS this lists all tables which have a column named '?', which is not what I'm after. I'm after listing all columns referencing a certain column as a FOREIGN KEY.
> 
> Should be possible to dredge that out of pg_constraint ... about like
> this:
> 
> select confrelid::regclass, af.attname as fcol,
>        conrelid::regclass, a.attname as col
> from pg_attribute af, pg_attribute a,
>   (select conrelid,confrelid,conkey[i] as conkey, confkey[i] as confkey
>    from (select conrelid,confrelid,conkey,confkey,
>                 generate_series(1,array_upper(conkey,1)) as i
>          from pg_constraint where contype = 'f') ss) ss2
> where af.attnum = confkey and af.attrelid = confrelid and
>       a.attnum = conkey and a.attrelid = conrelid;
> 
> Deconstructing those arrays in parallel is a bit of a pain :-(

What can I say, you're the man. Thank you very much!

Needless to say that it would be nice if this information was available in the information_schema, I'm probably not the only one spending lots of time in there. It's probably not in in the standard, but i would be a nice PG-extention to allow retrieving that info in a more intuitive way.

For the archive, here is a complete example with table_name and column_name:

select confrelid::regclass, af.attname as fcol,
       conrelid::regclass, a.attname as col
from pg_attribute af, pg_attribute a,
  (select conrelid,confrelid,conkey[i] as conkey, confkey[i] as confkey
   from (select conrelid,confrelid,conkey,confkey,
                generate_series(1,array_upper(conkey,1)) as i
         from pg_constraint where contype = 'f') ss) ss2
where af.attnum = confkey and af.attrelid = confrelid and
      a.attnum = conkey and a.attrelid = conrelid 
  AND confrelid::regclass = 'my_table'::regclass AND af.attname = 'my_referenced_column';

-- 
Andreas Joseph Krogh <andreak(at)officenet(dot)no>
Senior Software Developer / CEO
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