Re: Teach pg_upgrade to deal with invalid databases

Here is what I have staged for commit, which I'm planning to do soon.

Thinking ahead to the automatic deletion project, I wonder if we should
make DROP DATABASE work more like CHECKPOINT. That is, it would mark the
database for deletion, but another process would do the actual work. That
way, dropping a database follows the same path every time, regardless of
whether the DROP command was interrupted. This would also open the door
for a DROP DATABASE option to initiate the drop without waiting for it to
complete, although I'm admittedly not sure that has many use-cases.

--
nathan