Raphael Hertzog wrote: > The version of the software called "git" (we have nothing better to > identify the internal format AFAIK). > > If the internal format changes, I expect that git will upgrade it in place > or something similar. However a source package published in a given > release is a git repository that nobody use and will thus never be > upgraded to a newer format. And after some time, we'll have lost the > ability to extract older source packages. In several ways, that doesn't make much sense. There's also some inaverdant FUD going on here. Here is the actual situation, as I understand it. Neither gzip nor tar files include an embedded version number and yet the tar format has several times been extended without breaking backwards compatability. The family of zip/compress formats is a mess and yet current gzip can extract every zip-like thing ever created. In a sense that's what "file format" means today -- even if the format changes, old versions are still supported. By contrast to old formats like tar, the git pack (and idx) formats _do_ contain a version number. Three versions exist: Version 1 was never broadly used. ("Throw one away".) Version 3 is not generated by current versions of git. Git might start generating it at some point in the future, but has already supported reading it since 2006 -- a positively Debianish update schedule. Version 2 is what everyone uses now. I'm confident that the current git object format will be supported as long as git exists. Changing that format and doing the "upgrade in place" you suggest git might do would change every sha1 in the git repository, breaking all references to the sha1s, including all signed tags, and all cloned repositories. New object file formats might be developed, but existing ones will always have to be supported going forward. Just because the git pack, idx, and object are relatively new file formats to tar or gz is not a reason to fear them changing in incompatible ways. -- see shy jo  Doesn't dpkg even support all the old variants of the deb format?
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