On Mar 31, 2006, at 2:54 PM, Jesus Cea wrote:

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> I'm using DURUS and my BerkeleyDB backend as a GIS repository. I store
> tiled maps in the storage. I have about 50000 maps, of 500Kbytes each.
> It works great. But since the images are stored compressed (PNG), I
> would like to avoid the zlib inherent compression in Durus, for
> performance reasons.
>
> The issue are not the "permanent" maps but the temporal ones, like "on
> the fly" maps with tracks layered over them, and things like that. I
> would rather prefer to not compress an already compressed PNG
> generated
> file.
>
> Any "documented" option?.
>
> I would like to be able to configure that, object by object. I'm aware
> of "WRITE_COMPRESSED_STATE_PICKLES" attribute in "serialize.py", but I
> would like to have a garantee of forward compatibility with future
> Durus
> releases.

Here's what I would do.
Set WRITE_COMPRESSED_STATE_PICKLES to False.
Add __getstate__() and __setstate__() methods to your persistent
classes that provide the customized compression behavior.
If you want compressed pickles for a certain class, make
the __getstate__() return a compressed pickle of self.__dict__
instead of the dict itself.  The __setstate__() must
have the corresponding inverse behavior.