BEGIN;

SET CONSTRAINTS ALL DEFERRED;
ALTER TABLE uuidTest DISABLE TRIGGER ALL;
ALTER TABLE uuidTest_ref DISABLE TRIGGER ALL;

ALTER TABLE uuidtest ALTER COLUMN uidTest TYPE uuid USING uidTest::uuid;
ALTER TABLE uuidtest_ref ALTER COLUMN uidTest TYPE uuid USING uidTest::uuid;

ALTER TABLE uuidTest ENABLE TRIGGER ALL;
ALTER TABLE uuidTest_ref ENABLE TRIGGER ALL;

COMMIT;

No combination of the transaction, constraint or trigger syntax seems to fix this.

/*
* Foreign key constraints are checked in a final pass, since (a) it’s
* generally best to examine each one separately, and (b) it’s at least
* theoretically possible that we have changed both relations of the
* foreign key, and we’d better have finished both rewrites before we try
* to read the tables.
*/

But the alter table commands were refactored significantly in the current version so you may need to get a copy of head to get this working.

CREATE TABLE uuidtest (
	uidTest CHAR(35) NOT NULL PRIMARY KEY
) WITHOUT OIDS;

INSERT INTO uuidtest VALUES ('C5F25CC3-1D72-822B-795706E5A2C8F6B1');
INSERT INTO uuidtest VALUES ('A5F01CC3-1D72-822B-795706E5A2C8F6B1');
INSERT INTO uuidtest VALUES ('D6F25CC3-1D72-822B-795706E5A2C8F6B1');
INSERT INTO uuidtest VALUES ('C5FC2CC3-1D72-822B-795706E5A2C8F6B1');
INSERT INTO uuidtest VALUES ('E5F25CC3-1D72-822B-795706E5A2C8F6B1');

create table uuidtest_ref (
	uidTest char(35) not null references uuidtest(uidTest) on update cascade on delete cascade
) WITHOUT OIDS;

INSERT INTO uuidtest_ref VALUES ('C5F25CC3-1D72-822B-795706E5A2C8F6B1');
INSERT INTO uuidtest_ref VALUES ('A5F01CC3-1D72-822B-795706E5A2C8F6B1');

But trying to run the ALTER TYPE doesn’t work:


ERROR: foreign key constraint "uuidtest_ref_uidtest_fkey" cannot be implemented
SQL state: 42804
Detail: Key columns "uidtest" and "uidtest" are of incompatible types: character and uuid.


I tried this with a transaction block, with deferred constraints, with disabled triggers, etc. I think the only option is to eliminate the FK and recreate it?

ALTER TABLE uuidTest DISABLE TRIGGER ALL;

ALTER TABLE uuidtest ALTER COLUMN uidTest TYPE uuid USING CAST(regexp_replace(uidTest, ‘([A-Z0-9]{4})([A-Z0-9]{12})’, ‘\\1-\\2′) AS uuid);

ALTER TABLE uuidTest ENABLE TRIGGER ALL;


SELECT * from uuidtest;
"c5f25cc3-1d72-822b-7957-06e5a2c8f6b1"
"a5f01cc3-1d72-822b-7957-06e5a2c8f6b1"
"d6f25cc3-1d72-822b-7957-06e5a2c8f6b1"
"c5fc2cc3-1d72-822b-7957-06e5a2c8f6b1"
"e5f25cc3-1d72-822b-7957-06e5a2c8f6b1"


And this test returned Yes:

#yesNoFormat(isValid(’guid’, “c5f25cc3-1d72-822b-7957-06e5a2c8f6b1″))#

There are some Transfer issues to solve but otherwise this makes it feasible. Thanks again!

ALTER TABLE uuidtest ALTER COLUMN uidTest TYPE uuid USING uidTest::uuid;

(I just found out about the USING keyword just recently: http://archives.postgresql.org/pgsql-sql/2008-11/msg00047.php)