Re:

David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> writes:
> On 8 May 2017 at 00:42, Igor Korot <ikorot01(at)gmail(dot)com> wrote:
>> Basically what I'd like to see is the definition of each column and
>> whether this column is part of primary/foreign key or not.

> information_schema.table_constraints is of no use to you then. There
> are no details about which column(s) the constraint applies to.

information_schema.constraint_column_usage might help, though you'll
still need to join that to other views.

> Likely you'll want to look at pg_constraint for contype in('p','f')
> and unnest(conkey) and join that to information_schema.columns. You
> may also need to think about pg_constraint.confkey, depending on if
> you want to know if the column is referencing or referenced in a
> foreign key constraint.

If you don't mind a PG-specific solution, that's the way to go, as
it will surely be more efficient than going through the information_schema
views. Also, there are things that act like constraints but aren't
SQL-standard, such as exclusion constraints; we don't reflect those
in information_schema, so if you want to include those then you
*must* look directly at the catalogs.

regards, tom lane