Andres Freund <andres@anarazel.de> writes:
> On 2015-05-08 22:08:31 -0400, Robert Haas wrote:
>> Of course, even the last one isn't totally bullet-proof. Suppose one
>> backend fails to absorb the new setting for some reason...
> I've a hard time worrying much about that one...
You should. At the very least, whatever recipe we write for changing
fsync safely has to include a clause like "wait for all postmaster
children to have absorbed the new fsync setting". The facts that (a) this
could be a long time and (b) there's no easy way to be entirely certain
about when it's done don't make it something you should ignore.
I wonder whether we should change fsync to be PGC_POSTMASTER and then
document the safe procedure as requiring a postmaster restart.
regards, tom lane