Leo Famulari writes: > On Sun, Feb 21, 2016 at 12:17:19PM +0300, Alex Kost wrote: >> Leo Famulari (2016-02-21 07:35 +0300) wrote: >> >> > On Thu, Jan 21, 2016 at 10:05:36PM +0100, Ludovic Courtès wrote: >> [...] >> >> I prefer 7! This is how Git usually truncates SHA1s, so it can’t be >> >> wrong. >> > >> > I stumbled across this email earlier, which reminded me of this >> > discussion about hash lengths: >> > https://lkml.org/lkml/2010/10/28/287 >> > >> > There are currently 13 7-character hash collisions in Guix's git repo: >> > >> > $ git rev-list --objects --all | cut -c1-7 | sort | uniq -dc >> > 2 0d2b24c >> > 2 11e0632 >> > 2 1f3ab8d >> > 2 229bd6c >> > 2 7c4a7b7 >> > 2 9ff8b63 >> > 2 aa27b56 >> > 2 c10c562 >> > 2 d96cdce >> > 2 dab4329 >> > 2 dc27d1c >> > 2 ea119a2 >> > 2 f56cc27 >> >> Hm, when I tried "git rev-list --objects --all" I got some ridiculous >> number of lines (I pressed C-c C-c after about 78000 lines). Does this >> command really do what you wanted? (I'm sorry I didn't RTFM well enough >> to understand what it does). > > It lists the objects in the repository, so not just commits. I'm not > presenting this as evidence that something is wrong with our repo, just > that 7 characters is not enough to unambiguously refer to things in git > repos of projects our size. For example, with `git show`. > > It's more of an informational link than a call to action. Although I am > updating all of our uses of git-reference to use the method we agreed > upon upthread, before any of those upstream repos grow too large for the > identifiers we are currently using.
Yes, short identifiers probably should not be relied upon. For an entertaining article on the subject, I offer this one, which is similar but in GPG land: http://www.asheesh.org/note/debian/short-key-ids-are-bad-news.html
