From: pgsql-general-owner@xxxxxxxxxxxxxx [mailto:pgsql-general-owner@xxxxxxxxxxxxxx] On Behalf Of Moshe Jacobson Sent: Friday, March 28, 2014 10:31 AM To: pgsql-general Subject: Help with exclusion constraint Take the following table: CREATE TABLE exclusion_example AS ( pk_col integer primary key, fk_col integer not null references other_table, bool_col boolean not null ); I want to ensure that for any given value of fk_col that there is a maximum of one row with bool_col = true. I wanted to write an exclusion constraint such as this: alter table exclusion_example add exclude using btree ( fk_col with = , bool_col with and ); .......................... .......................... .......................... Moshe Jacobson Manager of Systems Engineering, Nead Werx Inc. 2323 Cumberland Parkway * Suite 201 * Atlanta, GA 30339 "Quality is not an act, it is a habit." - Aristotle For this: "any given value of fk_col that there is a maximum of one row with bool_col = true." why don't you (instead) create partial unique index: CREATE UNIQUE INDEX on exclusion_example(fk_col, bool_col) WHERE bool_col IS TRUE; Regards, Igor Neyman -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
