Affects: users of databases/postgresql* and other software using PostgreSQL to run

Author: kbowling@FreeBSD.org

Reason: 
  The default version of PostgreSQL has been switched from 13 to 15.
  The upgrade procedure can use up twice the space the databases
  currently needs. If you have a big amount of stored data take a
  closer look at the manpage of pg_upgrade for avoidance and/or
  speedup of the upgrade.

  The upgrade instructions consider a basic usage and do not match
  complex scenarios like replication, sharding, or similar.

  Upgrade instructions:

  First stop your PostgreSQL, create PostgreSQL-binaries and backup your data.
  If you have another Version of PostgreSQL installed, for example 13, your
  files are named according to this.

  # service postgresql stop
  # pkg create postgresql13-server postgresql13-contrib
  # mkdir /tmp/pg-upgrade
  # tar xf postgresql13-server-13.12.pkg -C /tmp/pg-upgrade
  # tar xf postgresql13-contrib-13.12.pkg -C /tmp/pg-upgrade
  # pkg delete -f databases/postgresql13-server databases/postgresql13-contrib databases/postgresql13-client

  Now update PostgreSQL:

    pkg user:
    # pkg install databases/postgresql15-server databases/postgresql15-contrib
    # pkg upgrade

    Portmaster users:
    # portmaster databases/postgresql15-server databases/postgresql15-contrib
    # portmaster -a

    Portupgrade users:
    # portinstall databases/postgresql15-server databases/postgresql15-contrib
    # portupgrade -a

  After installing the new PostgreSQL version you need to convert
  all your databases to new version:

  # su -l postgres -c "/usr/local/bin/initdb --encoding=utf-8 --lc-collate=C -D /var/db/postgres/data15 -U postgres"
  # su -l postgres -c "pg_upgrade -b /tmp/pg-upgrade/usr/local/bin/ -d /var/db/postgres/data13/ -B /usr/local/bin/ -D /var/db/postgres/data15/ -U postgres "

  Now the migration is finished. You can start PostgreSQL again with:

  # service postgresql start

  ATTENTION:
  1) The default user changed from "pgsql" to "postgres" in 11. The migration steps above now assume
     the "postgres" database user and FreeBSD user.
  2) See the updating entry 20190829 if you are updating from a release prior to 11.
  3) If you use non-default initdb options, you have to adjust the initdb-command accordingly