Thread: dump/restore needed when switching from 32bit to 64bit processor architecture?

dump/restore needed when switching from 32bit to 64bit processor architecture?

From
Dirk Lutzebäck
Date:
Hi,

when have a 8.0.3 database running on a XEON machine. We want to replace
it with an Opteron where postgresql is to be compiled with 64bit. Do we
need a dump/restore or can we just start the db with the new compilation?

Regards,

Dirk


=?ISO-8859-1?Q?Dirk_Lutzeb=E4ck?= <lutzeb@aeccom.com> writes:
> when have a 8.0.3 database running on a XEON machine. We want to replace
> it with an Opteron where postgresql is to be compiled with 64bit. Do we
> need a dump/restore or can we just start the db with the new compilation?

I'd bet you need a dump/restore --- MAXALIGN is most likely different
on the two platforms.  If it isn't, then maybe you could get away with
this, but it's definitely risky.

            regards, tom lane

Re: dump/restore needed when switching from 32bit to 64bit

From
Dirk Lutzebäck
Date:
Thanks Tom,

we now stay with 32bit to allow backward compatibilty with XEON which is needed as a fail-over system.

The question is which gcc cflags are best used with XEON and Opteron to achieve fail-over compatibility. This is what we used for postgresql 8.0.3:

XEON, RHEL 3.0 AS:
    CFLAGS = "-mcpu=pentium4 -march=pentium4"

Opteron 875, RHEL 3.0 AS,  gcc version 3.2.3 20030502 (Red Hat Linux 3.2.3-42):
    CFLAGS = "-Acpu=x86_64 -Amachine=x86_64"

Do we still need a dump/restore with this config?

Regards,

Dirk


Tom Lane wrote:
Dirk Lutzebäck <lutzeb@aeccom.com> writes: 
when have a 8.0.3 database running on a XEON machine. We want to replace 
it with an Opteron where postgresql is to be compiled with 64bit. Do we 
need a dump/restore or can we just start the db with the new compilation?   
I'd bet you need a dump/restore --- MAXALIGN is most likely different
on the two platforms.  If it isn't, then maybe you could get away with
this, but it's definitely risky.
		regards, tom lane 

Re: dump/restore needed when switching from 32bit to 64bit

From
Peter Eisentraut
Date:
Dirk Lutzebäck wrote:
> The question is which gcc cflags are best used with XEON and Opteron
> to achieve fail-over compatibility.

Configure both ways and run a diff over the generated pg_config.h files.
If there are differences, then there's a potential for trouble.  (No
differences don't say there won't be trouble, but it'd be far less
likely.)

--
Peter Eisentraut
http://developer.postgresql.org/~petere/