Re: Page Checksums + Double Writes

David Fetter <david@fetter.org> writes:
> There's a separate issue we'd like to get clear on, which is whether
> it would be OK to make a new PG_PAGE_LAYOUT_VERSION.

If you're not going to provide pg_upgrade support, I think there is no
chance of getting a new page layout accepted.  The people who might want
CRC support are pretty much exactly the same people who would find lack
of pg_upgrade a showstopper.

Now, given the hint bit issues, I rather doubt that you can make this
work without a page format change anyway.  So maybe you ought to just
bite the bullet and start working on the pg_upgrade problem, rather than
imagining you will find an end-run around it.

> The issue is that double writes needs a checksum to work by itself,
> and page checksums more broadly work better when there are double
> writes, obviating the need to have full_page_writes on.

Um.  So how is that going to work if checksums are optional?
        regards, tom lane