Re: 9.4 regression

Stephen Frost <sfrost@snowman.net> writes:
> * Andres Freund (andres@2ndquadrant.com) wrote:
>> I'd vote for adding zeroing *after* the fallocate() first. That's what's
>> suggested by kernel hackers and what several other large applications
>> do. As it looks like it's what we would have to do if we ever get to use
>> fallocate for relation extension where we would have actual benefits
>> from it.

> Does that actually end up doing anything different from what we were
> doing pre-patch here?  At best, it *might* end up using a larger extent,
> but unless we can actually be confident that it does, I'm not convinced
> the additional complexity is worth it and would rather see this simply
> reverted.

> One might ask why the kernel guys aren't doing this themselves or
> figuring out why it's necessary to make it worthwhile.

The larger picture is that that isn't the committed behavior,
but a different one, one which would need performance testing.

At this point, I vote for reverting the patch and allowing it to be
resubmitted for a fresh round of testing with the zeroing added.
And this time we'll need to do the testing more carefully.
        regards, tom lane