Re: pg_basebackup vs. Windows and tablespaces

On Sat, Nov 15, 2014 at 12:01 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> On Fri, Nov 14, 2014 at 1:15 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > Generally I'd be in favor of avoiding platform-dependent code where
> > possible, but that doesn't represent a YES vote for this particular
> > patch. It looks pretty messy in a quick look, even granting that the
> > #ifdef WIN32's would all go away.
>
> Hmm, OK. I have not read the patch. Hopefully that's something that
> could be fixed.
>
> > A larger question here is about forward/backward compatibility of the
> > basebackup files. Changing the representation of symlinks like this
> > would break that. Maybe we don't care, not sure (is there already a
> > catversion check for these things?). Changing the file format for only
> > some platforms seems like definitely a bad idea though.
>
> What are the practical consequences of changing the file format? I
> think that an old backup containing symlinks could be made to work on
> a new server that knows how to create them,

So if I understand correctly, by *old backup* you mean backup created
by 9.5 and by *new server*, you mean server > 9.5, if yes the current
design should handle it.

However if the backup is created on version < 9.5 using pg_basebackup
of same version and trying to restore it with server >=9.5 won't work,
because server won't have the information about symlinks.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com