Laurenz Albe wrote:
> Two concurrent sessions perform statements against one database. The
> sessions are named s1 and s2 in this example.
>
> s1=> CREATE TABLE x(i integer);
>
> s2=> BEGIN;
> s2=> CREATE UNIQUE INDEX x_pkey ON x(i);
>
> s1=> DROP TABLE x;
> (Session hangs)
>
> s2=> COMMIT;
>
> Now Session s1 will unblock and succeed in dropping the table. The index,
> however, remains in pg_class, pg_depend, and pg_index.
Hmm. So this is the bug that Tom mentioned on race conditions on
pg_depend. Interesting. I think the solution is to add more strict
locking when registering stuff in pg_depend, like the pg_shdepend code
does.
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.