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Re: Branching(copying) over merge and commit

From: Joshua Varner <jlvarner_at_gmail.com>
Date: 2005-11-04 23:14:17 CET

On 11/4/05, Duncan Murdoch <subversion@murdoch-sutherland.com> wrote:
[snip]
>
> The second part of Berlin's question, "Is there a lot wasted by doing
> constant copying", would seem to depend on how Subversion stores the
> deltas internally. I've read about that before (how FSFS is different
> than using BDB), but I don't remember the details well enough, and can't
> find the reference.
>
> Can anyone point it out to me? I.e. a document describing what is
> stored in the deltas.
>
My understanding is that BDB stores a full text copy of the most current
revision and reverse deltas of all older ones. FSFS stores deltas from the
first version exclusively.

Copies share storage of their history prior to the point of the copy, then
they diverge, so a long standing branch can have double the space of a
file only on trunk, i.e. The delta is stored once when initially made, then
again when it is merged, but I doubt this is a severe bottle neck, I haven't
heard anyone complaining about it.

Possibly this will be made more efficient when better merge tracking is
present, but I don't know what the thoertical limit of this compression is.

Josh

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Received on Fri Nov 4 23:16:02 2005

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