Re: BUG #7573: data loss in corner case using delete_old_cluster.sh (pg_upgrade) - Mailing list pgsql-bugs

From Bruce Momjian
Subject Re: BUG #7573: data loss in corner case using delete_old_cluster.sh (pg_upgrade)
Date
Msg-id 20121004191201.GA11759@momjian.us
Whole thread Raw
In response to Re: BUG #7573: data loss in corner case using delete_old_cluster.sh (pg_upgrade)  (Maxim Boguk <maxim.boguk@gmail.com>)
List pgsql-bugs
On Thu, Oct  4, 2012 at 10:40:19AM +1000, Maxim Boguk wrote:
>
>     > Test database have a bit unusual tablespace layout:
>     > main tablespace partition was mounted inside data directory of the old
>     > cluster...
>     > E.g.:
>     > data directory - /var/lib/postgresql/9.2/main
>     > main tablespace (another partition mount point) -
>     > /var/lib/postgresql/9.2/main/largedb
>
>     Can you show us the data directory path of the old and new clusters?
>
>
> --old-datadir=/var/lib/postgresql/9.0/main
> --new-datadir=/var/lib/postgresql/9.2/main
>
> second partition used as tablespace were mounted as:
> /var/lib/postgresql/9.0/main/largedb
>
>
>
>     pg_upgrade really doesn't know what is inside that old cluster, so it
>     just deletes everything under the data directory.
>
>
> Hmm... may be good idea to try opposite way:
> default directories and files layout in PostgreSQL data directory well
> documented and almost never changes.
> May be instead of rm -rf whole data directory try rm -rf only files and
> directories which sure belong to the PostgreSQL?
>
> Something along with:
> 1)rm -rf base global pg_clog pg_multixact ... and so on
> 2)produce warning if any unusual files left in data directory after that (but
> not delete them).
> 3)delete data directory itself only if that directory completely empty after
> step 1 and 2
>
> PS: I know that solution will be not completely error-prone but it will prevent
> most probably data-loss scenarios. So it's better then nothing.
>
> PS: I also think deleting postgresql.conf and pg_hba.conf from old data
> directory is wrong move too... if admin forget copy pg_hba.conf to the new
> cluster - these settings could be lost forever after delete_old_cluster.sh .

This all seems like a step backwards and adds complexity that will fail.

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

  + It's impossible for everything to be true. +

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