Re: Huge win, compressing a window of delta runs as a unit

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Hi,

On Thu, 17 Aug 2006, Nicolas Pitre wrote:

> On Thu, 17 Aug 2006, Johannes Schindelin wrote:
> 
> > On Thu, 17 Aug 2006, Jon Smirl wrote:
> > 
> > > On 8/17/06, Johannes Schindelin <Johannes.Schindelin@xxxxxx> wrote:
> > > > At least, the delta-chains should be limited by size (_not_ by number of
> > > > deltas: you can have huge deltas, and if you have to unpack 5 huge deltas
> > > > before getting to the huge delta you really need, it takes really long).
> > > 
> > > This is not an obvious conclusion.
> > 
> > The big win is bought by having _one_ zlib stream for multiple deltas, 
> > right?
> > 
> > So, everytime you want to access the _last_ delta in the chain, you unpack 
> > _all_ of them.
> 
> This is the case whether deltas are separately deflated or not.

Oh, now I get it! The delta chain is comprised of exactly those deltas 
which are needed to reconstruct a certain object from another object which 
was stored undeltified in the pack.

Now it makes sense to me that they could be bundled before being deflated. 
In the pack-index, the objects of that delta-chain could just point to 
the delta-chain object. Which has a mini-index in its extended header.

Or did I misunderstand again?

Ciao,
Dscho

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