Just did an upgrade from postgres 10.x to 11.x on a test machine..
The guide on the Gentoo Wiki is pretty good, but a few things I forgot at first:
First off when initializing the new cluster with "
emerge --config =dev-db/postgresql-11.1" making sure the DB init options are the same as the old cluster. They are stored in
/etc/conf.d/postgresql-XX.Y so just make sure PG_INITDB_OPTS collation ,.. match - if not delete the new cluster and re-run emerge --config ;)
The second thing was
pg_hba.conf: make sure to re-add extra user/db/connection permissions again (in my case I ran diff and then just copied the old config file as the only difference was the extra permissions I had added)
The third thing was
postgresql.conf: here I forgot to make sure
port are the same as in the old config (I did not copy this one as there are a lot more differences here. -- and of course check the rest of the config file too (diff is your friend ;) )
other than that
pg_upgrade worked really well for me and it is now up and running agian.