Re: Database file compatability

On Mon, Sep 26, 2005 at 07:05:28PM -0400, Tom Lane wrote:
> "Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu> writes:
> > ""Jim C. Nasby"" <jnasby(at)pervasive(dot)com> wrote
> >> If a database is created with a 64 bit version of initdb, would a 32bit
> >> backend be able to talk to it? Likewise, would a backend compiled by a
> >> different compiler be able to?
>
> > The key problem I believe is the serials of ALIGNOF macros. Especially for
> > MAX_ALIGNOF. Different Hardware/OS/compiler will have different
> > understanding of it.
>
> Yeah. It might be worth adding MAX_ALIGNOF to the set of configuration
> data stored in pg_control, just to be sure you couldn't shoot yourself
> in the foot that way.

PLEASE. :)

ISTM that 64 bit is becomming much more common, so I think the odds of
someone going from a 32 to 64 bit (or vice-versa) version of PostgreSQL
on the same machine is much larger now than it has been in the past. I
think we really need to protect this as much as possible. This isn't so
much a foot-gun as a foot-nuclear-weapon.

Would I be correct in assuming that doing this for 8.1 would require
another initdb? :/ For something as minor as this, would it be
reasonable to ship a utility to avoid the initdb? I'd very much like to
see this in 8.1...
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461