Re: Whither delta combiner (Re: SVN_STREAM_CHUNK_SIZE way too low?)

Greg Hudson <ghudson@MIT.EDU> writes:
> Do we understand why everything goes to hell when plaintexts spill over
> the window size? Windows are there to restrict memory usage, not make
> things worse.

No, we don't really, I think. The first task in addressing issue

   http://subversion.tigris.org/issues/show_bug.cgi?id=531

is to determine *why* we see the performance we do, and gather a ton
of statistics, imho.

> Another option is to apply the deltas streamily and try to keep the
> number of deltas small, by using some technique like skiplist deltas.
> If we did that, then even if there are 1024 revs of a file, there should
> be no more than about 20 deltas between any two revs, for at most 7.5MB
> of space required. (Which is still kind of big... we could cut it down
> to 2*windowsize by using a specialized chain-delta applicator which
> shares the destination view buffer of one delta and the source view
> buffer of the next. That might be over-optimizing, though.)

Hmmm... Could you describe this in more detail?

-K

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Received on Sat Oct 21 14:37:05 2006