Re: MERGE/SPLIT PARTITIONS issues/questions

> I'm worried that despite the documentation, users might find this
> surprising -- and by the time they realize it happened, it might be
> too late.

This was one of my reasons for mentioning it. Printing out at least a
WARNING for them would make them more visible (but it still has the
problem that the mistake already happened - what if the user didn't
dump the settings before splitting?), or it could be even an ERROR by
default that would require an extra clause to override. But either of
those requires at least the code to detect these issues.

My other worry is that it could be also confusing if we have silently
different behavior in 19 and 20. Let's say all of these will be
implemented in PG20 and later. And then a dba has to deal with some
merge/split on a PG19 server, and doesn't realize that some settings
are now missing, because it works differently in 20/21/... So maybe
even with support in later versions, it would require something like
INCLUDING ALL?