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Re: [Subclipse-dev] Revision graph and cache implementation

From: <Stefan.Fuhrmann_at_etas.com>
Date: Thu, 31 Jul 2008 17:49:53 +0200

"Alberto Gimeno" <gimenete_at_gmail.com> wrote on 07/23/2008 11:46:53 PM:

> In your conclusions you say that the current implementation is not
> scalable ("Large histories will take days or even weeks to get
> cached"). I agree that this is because of the 'exploding' issue.

Only as a side note: If I remember correctly, it took me ~30 hours
to fetch the log from apache.org. So, waiting days for the initial
cache fill is already the case for certain large, public repository
servers.

> About the second approach you say that "is likely to deliver a worse
> "perceived" performance". I think you say that because this approach
> needs to do more things when the user wants to see a graph. With the
> current implementation all graphs are calculated at the same time.
> With the 'alternative' approach this is different: the user needs to
> wait more for each single graph.

Agreed. My point with the "perceived" performance was as follows.
The best user experience you will get when things are fast enough
to be interactive. So, just loading the results should be considerably
faster than creating them. On the other hand, this advantage will
soon be offset by time necessary to update an "exploded" cache.

Another side note. There is a way to combine both approaches.
It would calculate file ids, organize changes by file id but only
add a smallish, constant factor to the data size. I made some
sketches a few months ago and hope to get the design done by
the end of this year. If all goes well, it will provide interactive
performance while effectively evaluating all copy and merge graphs
at once.

> However, what implementation do you think is the best? I think the
> second one. Because it is scalable.

Agreed. With your "incremental graph update" proposal it should
scale well for all common uses.

Regards,
Stefan^2.

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Received on 2008-07-31 17:50:05 CEST

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