On Friday 07 November 2008 21:09:33 Tom Lane wrote:
> Andreas Joseph Krogh <andreak@officenet.no> writes:
> > AFAICS this lists all tables which have a column named '?', which is not what I'm after. I'm after listing all
columnsreferencing 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
onlyone spending lots of time in there. It's probably not in in the standard, but i would be a nice PG-extention to
allowretrieving 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
(selectconrelid,confrelid,conkey,confkey, generate_series(1,array_upper(conkey,1)) as i from
pg_constraintwhere 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@officenet.no>
Senior Software Developer / CEO
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