Re: [RFC/WIP] Pluggable reference backends

On Mon, Mar 10, 2014 at 10:46:01AM -0700, Junio C Hamano wrote:

quoted

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No to SQLLite in git-core. Using it from JGit requires building
SQLLite and a JNI wrapper, which makes JGit significantly less
portable. I know SQLLite is pretty amazing, but implementing
compatibility with it from JGit will be a big nightmare for us.

That seems like a poor reason not to implement a pluggable feature for
git-core. If we implement it, then a site using only git-core can take
advantage of it. Sites with JGit cannot, and would use a different
pluggable storage mechanism that's supported by both. But if we don't
implement, it hurts people using only git-core, and it does not help
sites using JGit at all.

We would need to eventually have at least one backend that we know
will play well with different Git implementations that matter
(namely, git-core, Jgit and libgit2) before the feature can be
widely adopted.

I assumed that the current refs/ and logs/ code, massaged into pluggable
backend form, would be the first such. And I wouldn't be surprised to
see some iteration on that once it is easier to move from scheme to
scheme (e.g., to use some encoding of the names on the filesystem to
avoid D/F conflicts, and thus allow reflogs for deleted refs).

The first backend that is used while the plugging-interface is in
development can be anything and does not have to be one that
eventual ubiquitous one, however; as long as it is something that we
do not mind carrying it forever, along with that final reference
backend.  I take the objection from Shawn only as against making the
sqlite that final one.

Sure, I'd agree with that. I'd think something like an sqlite interface
would be mainly of interest to people running busy servers. I don't know
that it would make a good default.

-Peff