Hackers,
Experience and a read through backend/commands/tablecmds.c's
AlterTable() indicate that ALTER TABLE ... DISABLE TRIGGER obtains an
exclusive lock on the table (as does any ALTER TABLE).
Blocking other readers from a table when we've, within the body of a
transaction performing a bulk update operation where we don't want /
need triggers to fire, seems at first glance to be over-kill. I can
see how AlterTable()'s complex logic is made less complex through 'get
and keep a big lock', since most of its operational modes really do
need exclusive access, but is it strictly required for ... DISABLE /
REENABLE TRIGGER?
Could, say, RowExclusiveLock hypothetically provide adequate
protection, allowing concurrent reads, but blocking out any other
writers (for ENABLE / DISABLE TRIGGER) -- such as if driven through a
new statement other than ALTER TABLE -- such as "DISABLE TRIGGER foo
ON tbar" ?
Thanks!
----
James Robinson
Socialserve.com