Re: [RFC PATCH 00/18] Multi-pack index (MIDX)

On Mon, Jan 08, 2018 at 02:43:00PM +0100, Johannes Schindelin wrote:

Take the interactive rebase for example. It generates todo lists with
abbreviated commit names, for readability (and it is *really* important to
keep this readable). As we expect new objects to be introduced by the
interactive rebase, we convert that todo list to unabbreviated commit
names before executing the interactive rebase.

Your idea (to not care about unambiguous abbreviations) would break that.

I think that could be easily worked around for rebase by asking git to
check ambiguity during the conversion. Speed is much less of a problem
there, because we're doing a relatively small number of abbreviations
(compared to "git log --oneline --raw", which is abbreviating almost
every object in the repository).

But I agree it's a potential problem for other scripts that we might not
have control over. I hadn't really intended this to be the default
behavior (my patch was just trying to show the direction). But it does
make for a pretty awful interface if callers have to opt into it
manually ("git log --oneline --no-really-go-fast").

I am a bit curious if there's a bounded probability that people would
find acceptable for Git to give an ambiguous abbreviation. We already
accept 1 in 2^160, of course. But would, e.g., one in a million be OK?

-Peff