Re: [GENERAL] Help with exclusion constraint
On Fri, Mar 28, 2014 at 12:45 PM, hari.fu...@gmail.com wrote: I want to ensure that for any given value of fk_col that there is a maximum of one row with bool_col = true. This should be what you want: ALTER TABLE exclusion_example ADD CONSTRAINT ex EXCLUDE (fk_col WITH =) WHERE (bool_col); Yes, that would do the trick! I think I'll just set up a partial unique index as per Igor's suggestion, however. Thank you! Moshe Jacobson Manager of Systems Engineering, Nead Werx Inc. http://www.neadwerx.com 2323 Cumberland Parkway · Suite 201 · Atlanta, GA 30339 Quality is not an act, it is a habit. -- Aristotle
Re: [GENERAL] Help with exclusion constraint
Moshe Jacobson mo...@neadwerx.com writes: 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. This should be what you want: ALTER TABLE exclusion_example ADD CONSTRAINT ex EXCLUDE (fk_col WITH =) WHERE (bool_col); -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Help with exclusion constraint
On Fri, Mar 28, 2014 at 12:21 PM, Igor Neyman iney...@perceptron.comwrote: 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; Ahh yes, why didn't I think of that? Thank you. Moshe Jacobson Manager of Systems Engineering, Nead Werx Inc. http://www.neadwerx.com 2323 Cumberland Parkway · Suite 201 · Atlanta, GA 30339 Quality is not an act, it is a habit. -- Aristotle
[GENERAL] 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 ); But this doesn't work because and is not an operator. So I created my own operator (bool, bool): create function fn_boolean_and( bool, bool ) returns bool as $_$ select $1 and $2; $_$ language sql stable strict; create operator ( procedure = fn_boolean_and(bool, bool), leftarg = bool, rightarg = bool, commutator = ); But now when I try to create the exclusion constraint, I get the following: mydb=# alter table exclusion_example add exclude using btree ( fk_col with = , bool_col with and ); ERROR: operator (boolean,boolean) is not a member of operator family bool_ops DETAIL: The exclusion operator must be related to the index operator class for the constraint. I'm not sure what to do about this. Any help would be appreciated. Moshe Jacobson Manager of Systems Engineering, Nead Werx Inc. http://www.neadwerx.com 2323 Cumberland Parkway · Suite 201 · Atlanta, GA 30339 Quality is not an act, it is a habit. -- Aristotle
Re: [GENERAL] Help with exclusion constraint
From: pgsql-general-ow...@postgresql.org [mailto:pgsql-general-ow...@postgresql.org] On Behalf Of Moshe Jacobson Sent: Friday, March 28, 2014 10:31 AM To: pgsql-general Subject: [GENERAL] 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@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
