[Sugar-devel] Hypothetical sugar-0.90 material, draft 1.

[Benjamin M. Schwartz]

On 06/12/2010 10:49 AM, Bernie Innocenti wrote:
> Besides, the assumption that VCS-style deltas will work well with the
> binary files stored by most Sugar activities is... wishful at best.

It is one thing to say that we need a new datastore, and another to say
what the new datastore should look like.  I believe we have consensus on
the first part, and I'm fairly sure we don't have consensus on the second.

For the record, I am pushing a proposal in which no deltas are computed.
Files are stored as whole files.  Instead, I want each datastore object
version to consist of an entire directory.  To save space, files that are
identical inside multiple objects would only be stored once on disk.  This
allows us to store and launch Activity Bundles directly from the journal.
 It also allows slight modifications to objects (including activities) to
be stored efficiently if the object consists of multiple files and not all
of them are changed.

This is the de-duplication approach that was favored over three years ago [1].

I think Martin has listed some important use cases, and we should consider
them carefully.  One way to do that might be to try to reach a consensus
on design.  I believe the last attempt at this was over two years ago [2]
... and produced many good ideas but ultimately not much code.

--Ben

[1] http://lists.sugarlabs.org/archive/sugar-devel/2007-April/002344.html
[2]
http://lists.laptop.org/pipermail/community-news/2008-January/000095.html
, section 10.

--Ben

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