Re: pg_upgrade: delete_old_cluster.sh issues

On Mon, Nov 18, 2013 at 10:13:19PM -0500, Bruce Momjian wrote:
> On Tue, Nov 12, 2013 at 10:35:58AM +0000, Marc Mamin wrote:
> > Hello,
> >
> > IMHO, there is a serious issue in the script to clean the old data directory
> > when running pg_upgrade in link mode.
> >
> > in short: When working with symbolic links, the first step in
> > delete_old_cluster.sh
> > is to delete the old $PGDATA folder that may contain tablespaces used by the
> > new instance.
> >
> > in long, our use case:
>
> Rather than removing files/directories individually, which would be
> difficult to maintain, we decided in pg_upgrade 9.3 to detect
> tablespaces in the old data directory and report that and not create a
> delete script.  Here is the commit:
>
>        http://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=4765dd79219b9697d84f5c2c70f3fe00455609a1
>
> The problem with your setup is that while you didn't pass symbolic links
> to pg_upgrade, you did use symbolic links when defining the tablespaces,
> so pg_upgrade couldn't recognize that the symbolic links were inside the
> old data directory.
>
> We could use readlink() to go walk over all symbolic links, but that
> seems quite complex.  We could use stat() and make sure there are no
> matching inodes in the old data directory, or that they are in a
> different file system.  We could look for a directory named after the PG
> catversion in the old data directory.  We could update the docs.
>
> I am not sure what to do.  We never expected people would put
> tablespaces in the data directory.

I went with a doc patch, attached.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + Everyone has their own god. +