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

From
Johannes Schindelin <johannes.schindelin@gmx.de>
Date
Aug 17, 2006, 17:05 UTC
Message-ID
<Pine.LNX.4.63.0608171900130.28360@wbgn013.biozentrum.uni-wuerzburg.de>
In-Reply-To
<Pine.LNX.4.64.0608171220260.11359@localhost.localdomain>
Hi,
On Thu, 17 Aug 2006, Nicolas Pitre wrote:
Show 18 quoted lines
> On Thu, 17 Aug 2006, Johannes Schindelin wrote:
> 
> > On Thu, 17 Aug 2006, Jon Smirl wrote:
> > 
> > > On 8/17/06, Johannes Schindelin <Johannes.Schindelin@gmx.de> 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

Previous: Nicolas PitreNext: Jon Smirl
Message 8 of 36 in “Huge win, compressing a window of delta runs as a unit”
  1. Jon SmirlAug 16, 2006
  2. Shawn PearceAug 17, 2006
  3. Johannes SchindelinAug 17, 2006
  4. Johannes SchindelinAug 17, 2006
  5. Jon SmirlAug 17, 2006
  6. Johannes SchindelinAug 17, 2006
  7. Nicolas PitreAug 17, 2006
  8. Johannes SchindelinAug 17, 2006
  9. Jon SmirlAug 17, 2006
  10. Nicolas PitreAug 17, 2006
  11. Jon SmirlAug 17, 2006
  12. Nicolas PitreAug 17, 2006
  13. Jon SmirlAug 17, 2006
  14. Nicolas PitreAug 17, 2006
  15. Jon SmirlAug 17, 2006
  16. Nicolas PitreAug 17, 2006
  17. Nicolas PitreAug 18, 2006
  18. Jon SmirlAug 18, 2006
  19. Nicolas PitreAug 18, 2006
  20. Jon SmirlAug 18, 2006
  21. Nicolas PitreAug 21, 2006
  22. Shawn PearceAug 21, 2006
  23. Jakub NarebskiAug 21, 2006
  24. Jon SmirlAug 21, 2006
  25. Jon SmirlAug 18, 2006
  26. Johannes SchindelinAug 18, 2006
  27. Jon SmirlAug 18, 2006
  28. Linus TorvaldsAug 19, 2006
  29. Nicolas PitreAug 18, 2006
  30. Shawn PearceAug 21, 2006
  31. Jon SmirlAug 21, 2006
  32. Nicolas PitreAug 21, 2006
  33. Jon SmirlAug 21, 2006
  34. Nicolas PitreAug 21, 2006
  35. Nicolas PitreAug 21, 2006
  36. Nicolas PitreAug 21, 2006

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