Re: ReadBuffer(P_NEW) versus valid buffers

Tom Lane wrote:

> So ReadBuffer without hesitation zeroes out the page of data we just
> filled, and returns it for re-filling. There went some tuples :-(
>
> Although this is clearly Not Our Bug, it's annoying that ReadBuffer
> falls into the trap so easily instead of complaining. I'm still
> disinclined to try to change the behavior of mdread(), but what I am
> considering doing is adding a check here to error out if not PageIsNew.
> AFAICS, if we do find a buffer for a page supposedly past EOF, it should
> be zero-filled because that's what mdread returns in this case. So this
> change would prevent Dan's silent-overwrite scenario without changing the
> behavior for any legitimate case.
>
> Thoughts, problems, better ideas?
>

The check looks good - are we chasing up the Linux kernel (or Suse) guys
to get the bug investigated?

Cheers

Mark