Re: Protecting against unexpected zero-pages: proposal

On Tue, Nov 9, 2010 at 5:06 PM, Aidan Van Dyk <aidan@highrise.ca> wrote:
> So, for getting checksums, we have to offer up a few things:
> 1) zero-copy writes, we need to buffer the write to get a consistent
> checksum (or lock the buffer tight)
> 2) saving hint-bits on an otherwise unchanged page.  We either need to
> just not write that page, and loose the work the hint-bits did, or do
> a full-page WAL of it, so the torn-page checksum is fixed

Actually the consensus the last go-around on this topic was to
segregate the hint bits into a single area of the page and skip them
in the checksum. That way we don't have to do any of the above. It's
just that that's a lot of work.

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greg