auto-growing data size

[mark diener <rpzrpzrpz@gmail.com>]

Anybody have any idea on how to have the database file
grow until you get to the mapsize instead of pre-allocating the entire
mapsize (4GB) upon initialization?

mdb_env_set_mapsize() ;

I don't mind having an upper limit on the map size, but I think it
would be helpful
to have it grow to the upper limit, not preallocate the space on storage.

There are various areas in the documentation where it talks about
having the database not grow without bounds.

Comments?


Marco