Re: pg_upgrade and extra_float_digits

Andrew Dunstan <andrew@dunslane.net> writes:
> Bruce Momjian wrote:
>> FYI, I test pg_upgrade by loading the old cluster's regression database
>> from a pg_dump output file, then after the upgrade, I dump the
>> regression database of the new cluster and diff the changes.
>> 
>> The problem I just encountered is that pg_dump uses
>> extra_float_digits=-3 for 9.0, while previous releases used '2'.  I had
>> to do hack each server version to get a dump output that would match
>> without rounding errors --- it did eventually work and validated.

> That sounds like a disaster waiting to happen. The server version is 
> going to affect much more than just this behaviour, surely. Wouldn't it 
> be better to provide a pg_dump option to provide the extra_float_digits 
> setting?

What disaster?  That's only for test purposes, it has nothing to do with
actual data transfer.
        regards, tom lane