Re: We should add a "git gc --auto" after "git clone" due to commit graph

SZEDER Gábor <szeder.dev@gmail.com> writes:

I won't be actively engaged in this discussion soon, but I must say that "git gc" doing "garbage collection" is merely an implementation detail of optimizing the repository for further use. And from that point of view, what needs to be updated is the synopsis of the git-gc doc. It states "X and Y" above, but it actually is "Y by doing X and other things".

I understand your "by definition there is no garbage immediately after clone" position, and also I would understand if you find it (perhaps philosophically) disturbing that "git clone" may give users a suboptimal repository that immediately needs optimizing [*1*].

But that bridge was crossed long time ago ever since pack transfer was invented. The data source sends only the pack data stream, and the receiving end is responsible for spending cycles to build .idx file. Theoretically, .pack should be all that is needed---you should be able to locate any necessary object by parsing the .pack file every time you open it, and .idx is mere optimization. You can think of the .midx and graph files the same way.

I'd consider it a growing pain that these two recent inventions were and are still built as a totally optional and separate features, requiring completely separate full enumeration of objects in the repository that needs to happen anyway when we build .idx out of the received .pack.

I would not be surprised by a future in which the initial index-pack that is responsible for receiving the incoming pack stream and storing that in .pack file(s) while creating corresponding .idx file(s) becomes also responsible for building .midx and graph files in the same pass, or at least smaller number of passes. Once we gain experience and confidence with these new auxiliary files, that ought to happen naturally. And at that point, we won't be having this discussion---we'd all happily run index-pack to receive the pack data, because that is pretty much the fundamental requirement to make use of the data.

[Footnote]

*1* Even without considering these recent invention of auxiliary
    files, cloning from a sloppily packed server whose primary focus
    is to avoid spending cycles by not computing better deltas will
    give the cloner a suboptimal repository.  If we truly want to
    have an optimized repository ready to be used after cloning, we
    should run an equivalent of "repack -a -d -f" immediately after
    "git clone".