Re: Guidance Needed for PostgreSQL Upgrade from 12 to 15

> On Nov 18, 2024, at 12:10 PM, Achilleas Mantzios <a.mantzios@cloud.gatewaynet.com> wrote:
>
>
> I'd like to add if someone can tolerate some seconds of downtime, with logical replication it is possible to swap the
rolesof publisher / subscriber so that one can keep the old database as a means of extra safety. If his/her app breaks
beyondrepair and there is no time for fixing, one can simply go back to the old DB with some minor adjustments (such as
sequences).

In the same vein, if one's file system offers atomic snapshots:

1) shut down PG
2) run pg_upgrade with the hard links option
3) take snapshot
4) start up new PG

Now, if there's a failure, you can go back to the snapshot and either start up the old PG, or do some troubleshooting
andtry upgrading again.