On Fri, Mar 12, 2021 at 10:53:11AM -0600, tsuraan wrote: > > He/she wants to run the standby, I guess in read-only mode, while > > pg_upgrade is running, which is why I didn't even bother to mention > > that. I think if downtime is the critical for this person, he/she > > should be using logical replication for the upgrade. pg_upgrade really > > wants full control of the primary/standbys during its operation, and if > > you can't do that, pg_upgrade is not the right tool to use. > > This thread blew up a bit overnight, so I guess I might be getting a > bit repetitive, but it's less about super low downtime and more about > just not having all that much control over everything. The systems are > installed all over the world, and the upgrade process is very solid > and well understood (by my client's devs), but it's pretty reliant on > the main database being running, and also standby systems are fairly > independent, so doing a lot of coordination is somewhere between > complicated and maybe not entirely possible. > > I do just want to clarify the bit about pg_upgrade wanting full > control over standbys. I'm looking over the page again, and it does > list some prereqs to make sure things will run smoothly on the > standby, but if I do just abandon the standby systems and do a new > pg_basebackup on them once the master is running again, that's not > going to cause any issues on the master, right? I haven't had any > explosions in testing, but none of my test systems are anywhere near > as large or busy as the larger customers, so I definitely could be > missing things. Right, just making new standbys is simple. The basic idea is that pg_upgrade will complain about anything that isn't exactly as required, to avoid invisible upgrade failures. When you started asking about exactly how we could stretch pg_upgrade, we started to have to discuss exactly what we could relax with 100% reliability, and we didn't come up with many options. We are happy to continue that discussion but we don't have any good ideas right now. -- Bruce Momjian <bruce@xxxxxxxxxx> https://momjian.us EDB https://enterprisedb.com The usefulness of a cup is in its emptiness, Bruce Lee
