Tinker wrote:

Hi!

Is there any mechanism in LMDB to give back disk space after some particular amount of row deletion, how does this work, if not are there any plans for it now?

No. LMDB keeps all space and reuses it for future write operations.

If there's not, as a user I need 2x disk space and some mechanism to be able to migrate, so automatic shrinking would be a great thing.

There's nothing automatic but you can use mdb_env_copy() to implement your own strategy.