content/blog/2010/01/the-real-difference-between-mercurial-and-git.markdown @ aa7aebed85bc

(
:title "The Real Difference Between Mercurial and Git"
:snip "It’s not their features."
:date "2010-01-20T21:56:00Z"
:draft nil

)

There are a
[lot](http://nubyonrails.com/articles/five-features-from-mercurial-that-would-make-git-suck-less)
of
[other](http://www.rockstarprogrammer.org/post/2008/apr/06/differences-between-mercurial-and-git/)
[blog](http://importantshock.wordpress.com/2008/08/07/git-vs-mercurial/)
[posts](http://jointheconversation.org/2008/11/24/on-mercurial.html)
and
[web sites](http://www.whygitisbetterthanx.com/)
comparing [Mercurial][] and [git][].

Some of them are just plain outdated or wrong
([whygitisbetterthanx.com](http://whygitisbetterthanx.com/) for example, lists
"cheap local branching" as a git advantage over Mercurial, when Mercurial
actually has [*cheaper* branching][hgbranch] than git!).

Even the ones that aren't factually incorrect often seem to focus on features
and speed. While this may have been relevant in the past, both systems have
borrowed so much from each other that I don't think it's a very big deal
today.

This post is about what I feel are the last, most *important* differences
between git and Mercurial.

[Mercurial]: http://mercurial-scm.org/
[git]: http://git-scm.com/
[hgbranch]: /blog/2009/08/a-guide-to-branching-in-mercurial/#branching-anonymously

<div id="toc"></div>

The Big Difference
------------------

I think there's still one very, very important difference left: **the systems
*feel* very different to use**.

This might sound trivial, but I don't think it is. How a system "feels"
matters. Version control is something you use *constantly*, so it's important
to find a system that fits your way of thinking.

I'm a visual learner, so I find it helpful to make visual analogies when I'm
trying to explain something. Here's how I visualize the difference between
Mercurial and git:

![Swiss Army Knife and Kitchen Utensils](/static/images/blog/2010/01/mercurial-vs-git.jpg "Mercurial vs. Git")

Each git command is like a Swiss Army knife. For example, `git checkout` can
switch the working directory to a new branch, update file contents to that of
a previous revision, and even create a new branch. It's an efficient way to
work once you learn all the arguments and how they interact with each other.

Mercurial is like a well-equipped kitchen — it has a lot of tools that each
do one simple, well-defined thing, and do it well. To switch the working
directory you use `hg update`. To update file contents to what they were at a
previous revision you use `hg revert`. To create a new branch you use `hg
branch`. This means there are more commands to learn, but each command is much
simpler and more specific to a single conceptual task.

I personally find Mercurial's philosophy easier to work with. It's easy for me
to wrap my head around commands when they're more modular and less monolithic.

For example, I find Mercurial's `help` entries easier to understand. This
might just be because git's `help` entries are simply too long to read and
digest when I'm in the middle of coding:

```console
$ git help checkout | wc -l
236

$ (hg help update && hg help branch && hg help revert) | wc -l
100
```

I realize that not everyone feels the same way as I do. If you like git's way
of thinking better, you should certainly use it.

Other Differences
-----------------

Aside from their "feels" I see two other big differences that still remain
between git and Mercurial.

### BitBucket and GitHub

A major difference between the two systems is their most popular hosting
sites: [BitBucket][] and [GitHub][]. GitHub is leaps and bounds above
BitBucket in pretty much any aspect you look at: graphic design, popularity,
speed, and/or features. Every time I've seriously considered moving to git it
was purely because of this disparity.

I don't like using git itself (though it's *far* better than SVN or CVS), but
GitHub is such an awesome site that I've considered switching just to use it.
You can chalk it up to "popularity" (i.e. git has more users, so GitHub is
more profitable and so has more money to spend on development), but the fact
is that GitHub is still far better than BitBucket.

[BitBucket]: http://bitbucket.org/
[GitHub]: http://github.com/

### Git's Index

One of the features that git users talk about often is git's
[index][gitindex]. Mercurial has the [record][] extension, but it's not really
the same thing.

I personally don't like the index. I feel that git encourages people to check
in changesets that contain code which they've never tested (or even built)
because the index is such a prominent part of git's workflow.

Yes, one can argue that you don't actually *push* changes until you've got a
working state. The problem is that when you then try to run `git bisect` later
to find a bug you'll have to waste time skipping over changesets that don't
build. You could use `git rebase --interactive` to fold partial changesets
into one big one, but again, my gut feeling is that few people actually bother
*testing* the results.

With all that said, I've [considered][] creating a Mercurial extension that
adds git's index functionality to Mercurial, because I think it would make the
transition to Mercurial easier for git users. I've had enough experience with
Mercurial's internals to know that such a thing is *possible*, but I simply
don't have the time to do it *all* myself. If you're interested in helping out
please let me know!

[gitindex]: http://book.git-scm.com/1_the_git_index.html
[record]: http://mercurial.selenic.com/wiki/RecordExtension
[considered]: http://twitter.com/stevelosh/status/7106305374