Обсуждение: Foreign key pg_dump issue and serial column type

Hi,

As a relative newbie to postgres, I've run into to weirdisms that I 
don't quite know how to handle:

1. I have a many-to-many table 'people_roles' containing fields 
'person_code' and 'role_code'. It links tables 'people' and 'roles'. 
There are foreign key constraints:

ALTER TABLE PEOPLE_ROLES add CONSTRAINT PRO_PEE_FK FOREIGN 
KEY(PERSON_CODE) REFERENCES PEOPLE(PERSON_CODE) ON DELETE CASCADE NOT 
DEFERRABLE INITIALLY IMMEDIATE;
ALTER TABLE PEOPLE_ROLES add CONSTRAINT PRO_ROE_FK FOREIGN 
KEY(ROLE_CODE) REFERENCES ROLES(ROLE_CODE) ON DELETE CASCADE NOT 
DEFERRABLE INITIALLY IMMEDIATE;

However, when I pg_dump the database and import it on another server, 
the tables are exported alphabetically, so when the 'people_roles' table 
is created with its foreign keys, the table 'roles' does not exist yet. 
Thus, the foreign key creation fails. Is there a way around it?

2. I've just discovered the 'serial' column type and tried to do this:
alter table people_roles alter column  people_roles_code type serial;

To my surprise, it fails:
ERROR:  type "serial" does not exist

However, I can create new tables with the 'serial' type without a hitch. 
Is it a bug or a feature?

I'm running postgres 8.0.3 on Fedora Core 4.

Thanks,
Simon
-- 

Simon (Vsevolod ILyushchenko)   simonf@cshl.edu            http://www.simonf.com

Terrorism is a tactic and so to declare war on terrorism
is equivalent to Roosevelt's declaring war on blitzkrieg.

Zbigniew Brzezinski, U.S. national security advisor, 1977-81

"Vsevolod (Simon) Ilyushchenko" <simonf@cshl.edu> writes:
> However, when I pg_dump the database and import it on another server, 
> the tables are exported alphabetically, so when the 'people_roles' table 
> is created with its foreign keys, the table 'roles' does not exist yet. 
> Thus, the foreign key creation fails. Is there a way around it?

Are you sure you are using 8.0 pg_dump?  That's a longstanding
deficiency in older versions, but 8.0 is not supposed to have a problem
with it.  If you're sure it's an up-to-date pg_dump, could you provide a
complete test case (ie, a script to create a database that pg_dump has
trouble with)?

> 2. I've just discovered the 'serial' column type and tried to do this:
> alter table people_roles alter column  people_roles_code type serial;
> To my surprise, it fails:
> ERROR:  type "serial" does not exist

Serial isn't quite a true type, and so it doesn't work in every context
that you might think.  It'd probably make sense for "alter column type"
to accept it, but for now what you gotta do is create a sequence
and set the column default manually.
        regards, tom lane