> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> >> I don't see how that reduces the total amount of disk traffic?
>
> > Well, right now we write the pre-image to WAL, then write the new page
> > over the old one. In my case, you just write the new, and somewhere
> > record that the old page is no longer active.
>
> The devil is in the details of that last little bit. How is "mark a
> page inactive" cheaper than "mark a tuple dead"? More specifically,
> how do you propose to avoid WAL-logging the page you are going to do
> this marking in? Seems you still end up with a WAL page image for
> something.
I was thinking of just throwing the inactive page number into WAL. Much
smaller than the entire page image. You don't touch the page. Does
that help?
-- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610)
853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill,
Pennsylvania19026
