Phil Endecott <spam_from_postgresql_general@chezphil.org> writes:
> I would understand this if I were doing an "ALTER TABLE", for example.
> But does adding or removing a trigger really count as "schema-altering"?
[ shrug... ] Hard to say. Probably depends a lot on what the trigger
does. I suppose we could at least reduce the lock from AccessExclusive
to Exclusive, which would allow concurrent readers (since SELECT by
definition doesn't fire any triggers).
No one's really gone through and taken a hard look at whether every
single DDL operation needs the maximum lock ...
regards, tom lane