Re: query system tables to find columns unique constraint is constraining?

"Beth Gatewood" <beth(at)vizxlabs(dot)com> writes:
> I have been fiddling around trying to figure out which columns some unique
> constraints are constraining by querying the system tables.....with zero
> luck.

Look at the pg_index row for the index that's implementing the
constraint.

Rather than messing with the pg_index entry directly, you might want to
use pg_get_indexdef(), which is a helper function for pg_dump:

regression=# create table foo (f1 int, constraint foo_f1 unique (f1));
NOTICE: CREATE TABLE / UNIQUE will create implicit index 'foo_f1' for table 'foo'
CREATE TABLE
regression=# select pg_get_indexdef(oid) from pg_class where relname = 'foo_f1';
pg_get_indexdef
----------------------------------------------------
CREATE UNIQUE INDEX foo_f1 ON foo USING btree (f1)
(1 row)

regards, tom lane