On Wed, Apr 17, 2013 at 06:33:58PM +0200, Florian Pflug wrote:
> > I was going to ask about the flexibility of pg_upgrade and checksums.
> > Right now you have to match the old and new cluster checksum modes, but
> > it seems it would be possible to allow pg_upgrade use from checksum to
> > no-checksum servers. Does the backend look at the pg_controldata setting,
> > or at the page checksum flag? If the former, it seems pg_upgrade could
> > run a a no-checksum server just fine that had checksum information on
> > its pages. This might give us more flexibility in changing the checksum
> > algorithm in the future, i.e. you only lose checksum ability.
>
> AFAIK, there's currently no per-page checksum flag. Still, being only
> able to go from checksummed to not-checksummed probably is for all
> practical purposes the same as not being able to pg_upgrade at all.
> Otherwise, why would people have enabled checksums in the first place?
Good point, but it is _an_ option, at least.
I would like to know the answer of how an upgrade from checksum to
no-checksum would behave so I can modify pg_upgrade to allow it.
-- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB
http://enterprisedb.com
+ It's impossible for everything to be true. +