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Re: Question about your git habits

From
Charles Bailey <charles@hashpling.org>
Date
Feb 23, 2008, 19:28 UTC
Message-ID
<20080223192858.GA10655@hashpling.org>
In-Reply-To
<998d0e4a0802231047t1338439cj1a1c98f046e6ebaf@mail.gmail.com>
On Sat, Feb 23, 2008 at 07:47:13PM +0100, J.C. Pizarro wrote:
Show 19 quoted lines
> On 2008/2/23, Charles Bailey <charles@hashpling.org> wrote:
> > You're confusing two things together here. Conceptually, the git
> >  database is a database of immutable objects. How it is stored is a
> >  lower level implementation detail (albeit a very important one in
> >  practice). The delta chains in the pack files are nothing to do with
> >  git objects.
> 
> In Documentation/git-repack.txt says:
> 
> git-repack is used to combine all objects that do not currently
> reside in a "pack", into a pack. It can also be used to re-organize
> existing packs into a single, more efficient pack.
> 
> A pack is a collection of objects, individually compressed, with
> delta compression applied, stored in a single file, with an
> associated index file.
> 
> ### Can you explain me that delta chains in the pack files are
>  nothing to do with git objects? ###

It's an abstraction thing. Perhaps I should have said that git objects have nothing to do with pack files to indicate the direction of the dependency.

> Is not it redundant to place git objects and pack files in the same repo?
> 1. Or erase the unnecesary pack files because there are git objects.
> 2. Or erase some git objects because there are delta chains in pack files
>      that can generate the same git objects erased previously.
Only if they overlap, but usually they don't.
Show 9 quoted lines
> > What is the weekly user? Why would the 'binary delta' be better than
> >  an incremental pack in this case?
> 
> Because the user wants to clone weekly 240 MiB in 1st week, 220 MiB in
> 2nd week, 205 MiB in 3rd week, .... 100 MiB repo! in Nth week instead of
> 240+1+1+1+1 MiB of incremental packs.
> 
> What is better for the user in the Nth week, 100 MiB repo or 244 MiB repo?
>

That depends, doesn't it. If the everyday workflow is quicker and easier a 244 MiB clone could well be acceptable, but if it's not there is always the option of a repack. I don't buy the premise that people want to be continually repacking to find the ultimate pack file, I don't think that the gain over a one-shot repack is ever going to be worth it.

Previous: J.C. PizarroNext: J.C. Pizarro
Message 27 of 29 in “Question about your git habits”
  1. Chase VentersFeb 23, 2008
  2. Tommy ThornFeb 23, 2008
  3. Steven WalterFeb 23, 2008
  4. Jan EngelhardtFeb 23, 2008
  5. Al ViroFeb 23, 2008
  6. Junio C HamanoFeb 23, 2008
  7. Al ViroFeb 23, 2008
  8. Junio C HamanoFeb 23, 2008
  9. Samuel TardieuFeb 23, 2008
  10. Daniel BarkalowFeb 23, 2008
  11. Jeff GarzikFeb 23, 2008
  12. Mike HommeyFeb 23, 2008
  13. Rene HermanFeb 23, 2008
  14. Willy TarreauFeb 23, 2008
  15. Sam RavnborgFeb 23, 2008
  16. Jakub NarebskiFeb 23, 2008
  17. J.C. PizarroFeb 23, 2008
  18. J.C. PizarroFeb 23, 2008
  19. Charles BaileyFeb 23, 2008
  20. J.C. PizarroFeb 23, 2008
  21. Charles BaileyFeb 23, 2008
  22. J.C. PizarroFeb 23, 2008
  23. Charles BaileyFeb 23, 2008
  24. J.C. PizarroFeb 23, 2008
  25. Charles BaileyFeb 23, 2008
  26. J.C. PizarroFeb 23, 2008
  27. Charles BaileyFeb 23, 2008
  28. J.C. PizarroFeb 23, 2008
  29. Mike HommeyFeb 23, 2008

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