Re: pg_basebackup vs. Windows and tablespaces

On Sun, Nov 16, 2014 at 6:15 AM, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
wrote:
> Amit Kapila wrote:
> > On Sat, Nov 15, 2014 at 12:03 AM, Alvaro Herrera <
alvherre(at)2ndquadrant(dot)com>
> > wrote:
> > >
> > > Amit Kapila wrote:
>
> > > I think symlink_label isn't a very good name. This file is not a
label
> > > in the sense that backup_label is; it seems more a "catalog" to me.
And
> > > it's not, in essence, about symlinks either, but rather about
> > > tablespaces. I would name it following the term "tablespace catalog"
or
> > > some variation thereof.
> >
> > This file is going to provide the symlink path for each tablespace, so
> > it not be bad to have that in file name. I agree with you that it's
more
> > about tablespaces. So how about:
> >
> > tablespace_symlink
> > symlink_tablespace
> > tablespace_info
>
> I think the fact that we use symlinks is an implementation detail;
> aren't them actually junction points, not symlinks, in some Windows
> cases?

Right, but they provide same functionality as symlinks and now we
are even planing to provide this feature for both linux and windows as
both Tom and Robert seems to feel, it's better that way. Anyhow,
I think naming any entity generally differs based on individual's
perspective, so we can go with the name which appeals to more people.
In case, nobody else has any preference, I will change it to what both
of us can agree upon (either 'tablespace catalog', 'tablespace_info' ...).

> > > One use case mentioned upthread is having the clone be created in the
> > > same machine as the source server. Does your proposal help with it?
> >
> > Sorry, but I am not getting which proposal exactly you are referring
here,
> > Could you explain in more detail?
>
> In the first message of this thread[1], Noah said:
>
> : A "pg_basebackup -Fp" running on the same system as the target cluster
will
> : fail in the presence of tablespaces; it would backup each tablespace to
its
> : original path, and those paths are in use locally for the very
originals we're
> : copying.
>

That use case got addressed with -T option with which user can relocate
tablespace directory (Commit: fb05f3c; pg_basebackup: Add support for
relocating tablespaces)

> > In general, if user took the backup (in tar format) using pg_basebackup,
> > this
> > patch will be able to restore such a backup even on the same server.
>
> I must be misunderstanding either you or Noah.
>

Does the above information addressed your question?

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