[ZODB-Dev] Heavy size increasing of database after adding an object

[Tim Peters]

[Manuel Markwort]
> I adding my own ZClass Objects in the data.fs. After adding a new
> instance of those objects the database size increases heavily in
> opposition of the real object size. Before I add the instance to the
> database it's size is 26.6MB, after commiting the transaction the size is
> about 26.9MB. After packing the database the size is 26.6MB again. What
> happened in the background? It is possible to avoid this high increasing
> of the database without packing after adding the object?

Sorry, there's really not enough info here to say much.  Start here:

    http://zope.org/Wikis/ZODB/FileStorageBackup

to learn about the structure of a FileStorage file.  It's pretty simple,
essentially some layers of admin info around a sequence of object pickles.
If your .fs grew by 0.3MB because of a transaction, then it's surely the
case that you modified objects the sum of whose pickles adds up to about
0.3MB.  That could be because you have non-persistent objects as attributes
of your persistent objects, so that they have to be pickled in full too --
but, again, there's not enough info here to guess anything.

The link above will tell you how to use fsdump.py.  Use that to learn
exactly which objects were modified by the transaction.