On Sun, Oct 23, 2016 at 8:38 AM, Jeff King <peff@xxxxxxxx> wrote: > On Sun, Oct 23, 2016 at 08:23:01AM +0700, Duy Nguyen wrote: > >> I hit the same problem sometimes, but in my case sometimes I >> accidentally do "git add" after "git add -p" and a configuration in >> "git commit -a" won't help me. I'd prefer we could undo changes in >> index instead. Something like reflog but for index. > > An index write always writes the whole file from scratch, so you really > just need to save a copy of the old file. Perhaps something like: > > rm -f $GIT_DIR/index.old > ln $GIT_DIR/index.old $GIT_DIR/index > ... and then open $GIT_DIR/index.tmp ... > ... and then rename(index.tmp, index) ... > > could do it cheaply. It's a little more complicated if you want to save > a sequence of versions, and eventually would take a lot of space, but > presumably a handful of saved indexes would be sufficient. Yeah. I had something [1] like that but never sorted out the UI for it :( > Another option would be an index format that journals, and you could > potentially walk back the journal to a point. That seems like a much > bigger change (and has weird layering, because deciding when to fold in > the journal is usually a performance thing, but obviously this would > have user-visible impact about how far back you could undo). v2 [2] goes in this direction (but not a full blown COW, the journal does not take part in any core operations of the index) [1] https://public-inbox.org/git/%3C1375597720-13236-1-git-send-email-pclouds@xxxxxxxxx%3E/ [2] https://public-inbox.org/git/1375966270-10968-1-git-send-email-pclouds@xxxxxxxxx/ -- Duy