Re: PL/pgSQL graph enumeration function hangs

"Charles F. Munat" <chas@munat.com> writes:
> Using pseudocode from Celko's "SQL for Smarties" book, I wrote the
> following function that builds a path enumeration table. I hope to
> trigger this function on the rare occasions that the organizations table
> is updated. But when I run this function, it hangs.

I think there might be something wrong with this query:

>        INSERT INTO organizations_path_enum
>            SELECT o1.parent_id, r1.child_id, (o1.depth + 1)
>            FROM organizations_path_enum o1, relationships r1
>                -- advance existing paths by one level
>            WHERE EXISTS (SELECT * FROM organizations_path_enum AS o2
> WHERE r1.parent_id = o2.child_id)
>                -- insert only new rows into the table
>            AND NOT EXISTS (SELECT * FROM organizations_path_enum AS o3
> WHERE o1.parent_id = o3.parent_id AND r1.child_id = o3.child_id);

I'm not totally clear on what this is supposed to accomplish, but
it seems like there should be some join clause between o1 and r1.

            regards, tom lane