Re: LMDB and Referential transparency

[Howard Chu <hyc@symas.com>]

Pierre-Étienne Meunier wrote:
> Hi,
>
> I love LMDB, thanks for writing it!

You're welcome.

> I wonder whether it would be possibly to
> add the following feature:

> When I change one of the databases (called for instance A) in my environment,
> I'd like to be able to still keep a copy of A as it was before, and make a new
> copy B, that would share all its memory with A, except the changes.

Not likely to happen. The change you're suggesting would require adding a 
reference counter to every page, among other things. The cost of such a change 
would be quite high, not worth it for a very obscure feature.

--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/