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RE: Deltas?

From: Stefan Boberg <sboberg2_at_team17.com>
Date: 2002-03-10 19:40:43 CET

> Now, all of this writing is happening in the *.db files in the
> repository. If you look at their sizes, they should barely grow at
> all -- just by the size of the one-line delta.

  Yes, I understand that this is how it is supposed to work. But as far
as I can see, this is not what is happening in my very basic tests. I
understand that the log files are used by BDB for transaction
journaling, and I can live with those. The real problem I have is that
when I look at the database directory, the "strings" file - which I
assume is the BDB table which stores the file deltas/data - grows much,
much more than the delta data size.

  My test data is a large Maya 3D scene, "test.ma", saved out in ASCII
format (file size = 49MB). I add the file to the repository, and as
expected the "strings" table data file grows to around 49-50MB. Now, I
move a single object in the scene along one axis and save the scene out
to a file again. I verify that the change is in TWO lines only using the
standard "diff" program. Now I proceed to commit my changes. As
expected, the log data generated is around 50MB, but the "strings" file
also grows by the same amount! (i.e. to around 100MB). Subsequent
modifications, no matter how small, generate exactly the same amount of
data - i.e. a full 49MB's worth of data.

  So as far as I can see, delta storage is not actually used in this
simple test case. Or, in case it is, it does not calculate the deltas
very well.

  As for the log.* files, I think it would be a very good idea to have
SVN delete them automatically... in my case especially, they could quite
easily dwarf the main repository data very quickly :)

Stef! :)

Stefan Boberg - R&D Manager, Team17 Software Ltd.
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Received on Sun Mar 10 19:41:35 2002

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