Magnus Hagander <magnus@hagander.net> writes:
> On Tue, Sep 25, 2012 at 4:07 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I'm a bit concerned about backwards compatibility issues. It looks to
>> me like existing versions of pg_restore will flat out reject files that
>> have a spec-compliant "ustar\0" MAGIC field. Is it going to be
>> sufficient if we fix this in minor-version updates, or are we going to
>> need to have a switch that tells pg_dump to emit the incorrect old
>> format? (Ick.)
> Do we officially support using an older pg_restore to reload a newer
> dump? I think not? As long as we don't officially support that, I
> think we'll be ok.
Well, for the -Fc format, we have an explicit version number, and
pg_restore is supposed to be able to read anything with current or prior
version number. We don't bump the version number too often, but we've
definitely done it anytime we added new features at the file-format
level. However, since the whole point of the -Ft format is to be
standard-compliant, people might be surprised if it fell over in a
backwards-compatibility situation.
Having said all that, I don't think we have a lot of choices here.
A "tar format" output option that isn't actually tar format has hardly
any excuse to live at all.
regards, tom lane