Thanks all for the feedback. It was a nice idea and it *almost*
works, but it seems like we just can't drop segmented mode. And the
automatic transition schemes I showed don't make much sense without
that goal.
What I'm hearing is that something simple like this might be more acceptable:
* initdb --rel-segsize (cf --wal-segsize), default unchanged
* pg_upgrade would convert if source and target don't match
I would probably also leave out those Windows file API changes, too.
--rel-segsize would simply refuse larger sizes until someone does the
work on that platform, to keep the initial proposal small.
I would probably leave the experimental copy_on_write() ideas out too,
for separate discussion in a separate proposal.