On Mon, Feb 21, 2022 at 10:10:15PM +0100, Christian Couder wrote: > > > Also, to have more protection we can either > > > > > > 1. add a config value that needs to be set to true for repack to remove > > > objects (repack.allowDestroyFilter). > > I don't think it's of much value. We don't have such config values for > other possibly destructive operations. > > > > 2. --filter is dry-run by default and prints out objects that would have been removed, > > > and it has to be combined with another flag --destroy in order for it to actually remove > > > objects from the odb. > > I am not sure it's of much value either compared to naming it > --filter-destroy. It's likely to just make things more difficult for > users to understand. On this and the above, I agree with Christian. > > I share the same concern as Robert and Stolee do. But I think this issue > > goes deeper than just naming. > > > > Even if we called this `git repack --delete-filter` and only ran it with > > `--i-know-what-im-doing` flag, we would still be leaving repository > > corruption on the table, just making it marginally more difficult to > > achieve. > > My opinion on this is that the promisor object mechanism assumes by > design that some objects are outside a repo, and that this repo > shouldn't care much about these objects possibly being corrupted. For what it's worth, I am fine having a mode of repack which allows us to remove objects that we know are stored by a promisor remote. But this series doesn't do that, so users could easily run `git repack -d --filter=...` and find that they have irrecoverably corrupted their repository. I think that there are some other reasonable directions, though. One which Robert and I discussed was making it possible to split a repository into two packs, one which holds objects that match some `--filter` criteria, and one which holds the objects that don't match that filter. Another option would be to prune the repository according to objects that are already made available by a promisor remote. An appealing quality about the above two directions is that the first doesn't actually remove any objects, just makes it easier to push a whole pack of unwanted objects off to a promsior remote. The second prunes the repository according to objects that are already made available by the promisor remote. (Yes, there is a TOCTOU race there, too, but it's the same prune-while-pushing race that Git already has today). > I am not against a name and some docs that strongly state that users > should be very careful when using such a command, but otherwise I > think such a command is perfectly ok. We have other commands that by > design could lead to some objects or data being lost. I can think of a handful of ways to remove objects which are unreachable from a repository, but I am not sure we have any ways to remove objects which are reachable. > > But as it stands right now, I worry that this feature is too easily > > misused and could result in unintended repository corruption. > > Are you worrying about the UI or about what it does? > > I am ok with improving the UI, but I think what it does is reasonable. I am more worried about the proposal's functionality than its UI, hopefully my concerns there are summarized above. Thanks, Taylor
