Re: [HACKERS] obsolete code in pg_upgrade

On Tue, Aug 22, 2017 at 8:28 PM, Peter Eisentraut
<peter.eisentraut@2ndquadrant.com> wrote:
> It seems to me that this code in pg_upgrade/check.c has been useless
> since at least version 9.1:
>
>     /* Is it 9.0 but without tablespace directories? */
>     if (GET_MAJOR_VERSION(new_cluster.major_version) == 900 &&
>         new_cluster.controldata.cat_ver < TABLE_SPACE_SUBDIRS_CAT_VER)
>         pg_fatal("This utility can only upgrade to PostgreSQL version
> 9.0 after 2010-01-11\n"
>                  "because of backend API changes made during
> development.\n");

I think I agree.  It seems to me that the version of pg_upgrade
shipped with release N only needs to support upgrades to release N,
not older releases.  There's probably room for debate about whether a
pg_upgrade needs to support direct upgrades FROM very old releases,
but we need not decide anything about that right now.

I think you could go ahead and rip out this code, but as it seems like
a non-critical change, -1 for back-patching it.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company