[RFC] Cheap re-pack?

[Robert Collins]

On Thu, 2007-09-06 at 19:09 -0400, Aaron Bentley wrote:
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> Robert Collins wrote:
> >>  AIUI, that's an expensive operation, because it requires
> >> generating deltas for 10 commits at re-pack time.
> > 
> > autopack preserves the existing deltas
> 
> Which existing deltas?  I thought every time you committed it would
> create a fulltext, since the plan was to have the last-committed
> revision be a fulltext.

That is a possibility which we can follow to make incremental commits
extremely fast (by doing no delta operations at all)

> > Autopack is intended to be cheap as possible, its only reason for
> > existence is to cap the latency generated by having multiple pack files
> > and their associated indices.
> 
> This would probably make sense if I understood why there are existing
> deltas.  As I understood it, there would be no existing deltas.

As John says, pack repos are currently a collection of logical knits
remapped to be temporally associated together (as opposed to identity
associated as knit repo's are). A growing number of operations operate
directly on the pack level without the knit intermediary reducing
overhead, but the stored data is still structured and encoded within the
pack as knit records, gzipped, same headers etc.

-Rob

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