Re: git-fetching from a big repository is slow

[Nicolas Pitre <nico@cam.org>]

On Fri, 15 Dec 2006, Johannes Schindelin wrote:

> Hi,
> 
> On Thu, 14 Dec 2006, Shawn Pearce wrote:
> 
> > Geert Bosch <bosch@adacore.com> wrote:
> > > Such special magic based on filenames is always a bad idea. Tomorrow  
> > > somebody
> > > comes with .zip files (oh, and of course .ZIP), then it's .jpg's other
> > > compressed content. In the end git will be doing lots of magic and  
> > > still perform
> > > badly on unknown compressed content.
> > > 
> > > There is a very simple way of detecting compressed files: just look  
> > > at the
> > > size of the compressed blob and compare against the size of the  
> > > expanded blob.
> > > If the compressed blob has a non-trivial size which is close to the  
> > > expanded
> > > size, assume the file is not interesting as source or target for deltas.
> > > 
> > > Example:
> > >    if (compressed_size > expanded_size / 4 * 3 + 1024) {
> > >      /* don't try to deltify if blob doesn't compress well */
> > >      return ...;
> > >    }
> > 
> > And yet I get good delta compression on a number of ZIP formatted files 
> > which don't get good additional zlib compression (<3%). Doing the above 
> > would cause those packfiles to explode to about 10x their current size.
> 
> A pity. Geert's proposition sounded good to me.
> 
> However, there's got to be a way to cut short the search for a delta 
> base/deltification when a certain (maybe even configurable) amount of time 
> has been spent on it.

Yes! Run git-repack -a -d on the remote repository.