Re: small downloads and immutable history (Re: clone breaks replace)

[Phillip Susi <psusi@cfl.rr.com>]

On 01/14/2011 03:53 PM, Jonathan Nieder wrote:
> Ah, I forgot the use case.  If you are using this to at long last get
> past the limitations (e.g., inability to push) of "fetch --depth",
> then yes, rewriting existing history is bad.

I'm not really talking about using --depth, but more of the project 
deciding to truncate the history in the central repository.

> So what's left is some way to make the "have" part of transport
> negotiation make sense in this context.  I'll be happy if it happens.

Good point.  Whether local history is short because of --depth or 
replace records, the same problem arises; the negotiation needs to be 
able to exclude older objects that are not present locally, rather than 
assuming that the client has the entire history if it has any at all. 
It seems like this should just require sending the server and end point 
in addition to a start point.  In other words, not just send ID of the 
most recent commit, but also the oldest that it has on hand, so that the 
server can be sure that it does not deltafy against objects prior to 
that commit.