Backing up objects in db file

[Chris Stiles]

Hi --

I have a program that stores all its data as pickled objects inside a
(berkeley) db file.

Having been bitten a couple of times when the format changed across linux
distribution upgrades, I'd like to write a simple program that dumps the
objects to some kind of text format, which can then be reconstituted into
objects later. It can't just dump out the pickle format, because that could
change between python versions.

There seem to be a few solutions in this space that nearly work - two
incomplete YAML implementations, and a similiar maturity XML thing. Does
anyone know of a solution that will both work, and is actively maintained ?

--
regards, chris

[Skip Montanaro]

Chris> I have a program that stores all its data as pickled objects
Chris> inside a (berkeley) db file.

Chris> Having been bitten a couple of times when the format changed
Chris> across linux distribution upgrades, I'd like to write a simple
Chris> program that dumps the objects to some kind of text format, which
Chris> can then be reconstituted into objects later. It can't just dump
Chris> out the pickle format, because that could change between python
Chris> versions.

Take a look at db2pickle.py and pickle2db.py in the Tools/scripts directory
of the source distribution. I have no idea if they are included in the
Windows installer. Here's the doc string from db2pickle.py:

Synopsis: db2pickle.py [-h|-g|-b|-r|-a] dbfile [ picklefile ]

Convert the database file given on the command line to a pickle
representation. The optional flags indicate the type of the database
(hash, btree, recno). The default is hash. If a pickle file is named it
is opened for write access (deleting any existing data). If no pickle
file is named, the pickle output is written to standard output.

Looking at that I can see I need to update the doc string. The flags mean:

-h - open as bsddb hash file
-g - open as gdbm file
-b - open as bsddb btree file
-r - open as bsddb recno file
-a - open using anydbm

Skip