On 2015-05-04 14:23:16 -0400, Robert Haas wrote:
> On Fri, May 1, 2015 at 10:41 AM, Abhijit Menon-Sen <ams@2ndquadrant.com> wrote:
> > As for the non-backpatchable 0002, I agree with Andres that it should be
> > included in 9.5; but I take it you're still not convinced?
>
> No, I'm not convinced. That patch will protect you in one extremely
> specific scenario: you turn off fsync, do some stuff, shut down, turn
> fsync back on again, and start up.
Hm. ISTM it'd not be hard to actually make it safe in nearly all
situations. What about tracking the last checkpoint's fsync setting and
do a fsync_pgdata() in the checkpointer at the end of a checkpointer if
the previous setting was off and the current one is on? Combined with
doing so at startup if the settings changed between runs, that should
give pretty decent protection. And seems fairly simple to implement.
Greetings,
Andres Freund