zfs retroactive compress and dedup command

[ChristophSchmidpeter]

As compression and and deduplication are not retroactive, wouldn't it make sense to have a command doing this?
So you could write something like
zfs retrocompress {on|off} {dataset}
and
zfs retrodedup {on|off} {dataset}

[ChristophSchmidpeter]

PS: how to write greater-than/less-than signs in github?

[rlaager]

This would be nice, but it's not really practical. You end up in "block-pointer rewrite" territory.

[rlaager]

Alternatively, see also #3013.