Re: LockDatabaseObject vs. LockSharedObject

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> It seems suspicious to me that LockSharedObject() calls
> AcceptInvalidationMessges() and LockDatabaseObject() does not. Since
> the only caller of LockSharedObject() at present is
> AcquireDeletionLock(), I'm not sure there's an observable bug here at
> the moment, but then again, I'm also not sure there isn't.

ITYM the only caller of LockDatabaseObject is AcquireDeletionLock.
Given that the other logic path in AcquireDeletionLock calls
LockRelationOid, which *will* result in an AcceptInvalidationMessages
call, it does seem pretty suspicious. The type of bug that you'd
expect to have from this is that a recent DDL change on a non-relation
object might not be seen by a concurrent drop being done on that object.

I'm not sure that we have any non-relation objects that are both complex
enough and changeable enough for there to be an observable bug here,
but it seems like a risk factor going forward. It seems to me both safe
and reasonable to add an AcceptInvalidationMessages call in HEAD.

regards, tom lane