> but major version upgrades are much much more of a pain on Postgres than on almost any other system I have ever used.
This is a thread comparing MySQL and Postgres and your claim is that postgres is harder to do major version upgrades than anything you have used??
Context is important here, have you honestly actually upgraded a MySQL node? It’s a lesson in pain and “major” version changes happen on minor versions, like the entire query planner completely trashing performance in 5.6->5.7
Postgres has two forms of updates:
1) in place binary upgrade.
Fast, clean, simple, requires that you have the binaries for the old and the new database.
2) dump/restore.
Serialise the database into text files, load a new database and deserialise those files into it.
Slow, but works flawlessly & consistently with relatively low danger.
MySQL can only do option 2.
You can sort of fake an “update” by abusing the fact that MYSQLs replication offers no guarantees, so you can make a new server a replica; then roll over. But it is impossible to know what data was lost in that transition and MySQL will happily continue without ever telling you.
I have experienced this behaviour in large e-commerce retailers. MySQL was very popular for a very long time and I am intimately aware of operational best practices and how they are merely patching over an insane system.