CLONE TABLE DATA TO <new_table>

Hello,

I wonder if it would be possible to have a fast table clone function
(data only) while copying the corresponding data files
instead of using the "CREATE TABLE AS" way.

pg_upgrade seems to have such a mechanisms, though it requires to first
stop the server...
This would of course require to lock the complete table and ensure that
all latest changes are flushed to the plates.
I don't know how are the plan about switching from UNLOGGED to LOGGED
tables, but I guess this might be required to start logging the table
only after the copy.

Background: I have daily tables with hourly imports which may contain >
100 Mio rows and require 7 indices on them.
In order to improve import performances, I first do a copy of the active
table, import new data and rebuild the indexes.

Thanks for your great job,

Marc Mamin