backward diffs in knits?

[John Arbash Meinel]

Robert Collins wrote:
...

>> I don't think backwards deltas should be generated "on-the-fly",
>> because
>> of the potential for a new corruption to lose old data.
> 
> I'm not sure what you mean here, in particular you can always perform a
> check of all data after the pull, if and only if we have altered
> representation.

I was thinking more at "per-commit" time, not so much at 'pull' time.
Simply because commit really only works with one revision at a time, and
it doesn't seem like you want to do a full integrity check, etc.

But pull will usually be operating on more (and also transmitting them
over the wire).

> 
>> However, it could make sense for an "archive" command. Where you
>> packaged up a bunch of older revisions to make them more dense, and
>> sort
>> of put them off to the side. They should still be accessible, but
>> maybe
>> they wouldn't be in the default search every time.
> 
> I see this as a variation on 'pack' - is that what you were thinking of?
> 

Same thing. Perhaps more of an obvious 'put it to the side', as in you
would not do it on recent revisions... But it is just an idea, not
something I thought through thoroughly.

John
=:->