[Python-Dev] The memo of pickle

Guido van Rossum guido@python.org
Wed, 07 Aug 2002 08:11:03 -0400

> I think that the tuple is not the problem here, it's the
> fact that so many objects are recorded in the memo to
> later rebuild recursive structures.
> Now, I believe that recursive structures in pickles are
> not very common, so the memo is mostly useless in these
> cases.

Use cPickle, it's much more frugal with the memo, and also has some
options to control the memo (read the docs, I forget the details and
am in a hurry).

> Perhaps pickle could grow an option to assume that a
> data structure is non-recursive ?! In that case, no
> data would be written to the memo (or only the id()
> mapped to 1 to double-check).

The memo is also for sharing.  There's no recursion in this example,
but the sharing may be important:

a = [1,2,3]
b = [a,a,a]

--Guido van Rossum (home page: http://www.python.org/~guido/)