On Wed, 2013-04-17 at 16:58 +0100, Greg Stark wrote: > On Wed, Apr 17, 2013 at 4:28 PM, Florian Pflug <f...@phlo.org> wrote: > > Is there any way we can change the checksum algorithm in 9.4 > > *without* breaking pg_upgrade? > > Personally I think we're going to need a solution for page format > changes someday eventually.... > > What advantages are we postponing now to avoid it? > > * 32-bit checksums? > * Being able to enable/disable checksums? > > Anything else?
I'm not sure that changing the page format is the most difficult part of enabling/disabling checksums. It's easy enough to have page header bits if the current information is not enough (and those bits were there, but Heikki requested their removal and I couldn't think of a concrete reason to keep them). Eventually, it would be nice to be able to break the page format and have more space for things like checksums (and probably a few other things, maybe some visibility-related optimizations). But that's a few years off and we don't have any real plan for that. What I wanted to accomplish with this patch is the simplest checksum mechanism that we could get that would be fast enough that many people would be able to use it. I expect it to be useful until we do decide to break the page format. Regards, Jeff Davis -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers