Re: [HACKERS] Incrementally Updated Backup

[Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>]

"Jim C. Nasby" <jim(at)nasby(dot)net> writes:
> My thought is that in many envoronments it would take much beefier
> hardware to support N postmasters running simultaneously than to cycle
> through them periodically bringing the backups up-to-date.

How you figure that?  The cycling approach will require more total I/O
due to extra page re-reads ... particularly if it's built on a patch
like this one that abandons work-in-progress at arbitrary points.

A postmaster running WAL replay does not require all that much in the
way of CPU resources.  It is going to need I/O comparable to the gross
I/O load of its master, but cycling isn't going to reduce that at all.

			regards, tom lane