Re: [HACKERS] WAL logging problem in 9.4.3?

Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> Interesting.  I wonder if it's possible that a relcache invalidation
> would cause these values to get lost for some reason, because that would
> be dangerous.

> I suppose the rationale is that this shouldn't happen because any
> operation that does things this way must hold an exclusive lock on the
> relation.  But that doesn't guarantee that the relcache entry is
> completely stable,

It ABSOLUTELY is not safe.  Relcache flushes can happen regardless of
how strong a lock you hold.
        regards, tom lane