Re: Page Checksums + Double Writes

On Tue, Dec 27, 2011 at 10:43 PM, Merlin Moncure <mmoncure@gmail.com> wrote:
>  I bet if you kept a judicious number of
> clog pages in each local process with some smart invalidation you
> could cover enough cases that scribbling the bits down would become
> unnecessary.

I don't understand how any cache can completely remove the need for
hint bits. Without hint bits the xids in the tuples will be "in-doubt"
forever. No matter how large your cache you'll always come across
tuples that are arbitrarily old and are from an unbounded size set of
xids.

We could replace the xids with a frozen xid sooner but that just
amounts to nearly the same thing as the hint bits only with page
locking and wal records.


-- 
greg