What is the Difference Between Mercurial and Git?

Question

I've been using git for some time now on Windows (with msysGit) and I like the idea of distributed source control. Just recently I've been looking at Mercurial (hg) and it looks interesting. However, I can't wrap my head around the differences between hg and git.

Has anyone made a side-by-side comparison between git and hg? I'm interested to know what differs hg and git without having to jump into a fanboy discussion.

Answer 1

One thing to notice between mercurial of bitbucket.org and git of github is, mercurial can have as many private repositories as you want, but github you have to upgrade to a paid account. So, that's why I go for bitbucket which uses mercurial.

Answer 2

I'm currently in the process of migrating from SVN to a DVCS (while blogging about my findings, my first real blogging effort...), and I've done a bit of research (=googling). As far as I can see you can do most of the things with both packages. It seems like git has a few more or better implemented advanced features, I do feel that the integration with windows is a bit better for mercurial, with TortoiseHg. I know there's Git Cheetah as well (I tried both), but the mercurial solution just feels more robust.

Seeing how they're both open-source (right?) I don't think either will be lacking important features. If something is important, people will ask for it, people will code it.

I think that for common practices, Git and Mercurial are more than sufficient. They both have big projects that use them (Git -> linux kernel, Mercurial -> Mozilla foundation projects, both among others of course), so I don't think either are really lacking something.

That being said, I am interested in what other people say about this, as it would make a great source for my blogging efforts ;-)

Answer 3

Yet another interesting comparison of mercurial and git: Mercurial vs Git. Main focus is on internals and their influence on branching process.

Answer 4

Nothing. They both do the same, both perform about equally. The only reason you should choose one over the other is if you help out with a project that already uses one..

The other possible reason for choosing one is an application or service which only supports one of the system.. For example, I pretty much chose to learn git because of github..

Answer 5

I work on Mercurial, but fundamentally I believe both systems are equivalent. They both work with the same abstractions: a series of snapshots (changesets) which make up the history. Each changeset knows where it came from (the parent changeset) and can have many child changesets. The recent hg-git extension provides a two-way bridge between Mercurial and Git and sort of shows this point.

Git has a strong focus on mutating this history graph (with all the consequences that entails) whereas Mercurial does not encourage history rewriting, but it's easy to do anyway and the consequences of doing so are exactly what you should expect them to be (that is, if I modify a changeset you already have, your client will see it as new if you pull from me). So Mercurial has a bias towards non-destructive commands.

As for light-weight branches, then Mercurial has supported repositories with multiple branches since..., always I think. Git repositories with multiple branches are exactly that: multiple diverged strands of development in a single repository. Git then adds names to these strands and allow you to query these names remotely. The Bookmarks extension for Mercurial adds local names, and with Mercurial 1.6, you can move these bookmarks around when you push/pull..

I use Linux, but apparently TortoiseHg is faster and better than the Git equivalent on Windows (due to better usage of the poor Windows filesystem). Both http://github.com and http://bitbucket.org provide online hosting, the service at Bitbucket is great and responsive (I haven't tried github).

I chose Mercurial since it feels clean and elegant -- I was put off by the shell/Perl/Ruby scripts I got with Git. Try taking a peek at the git-instaweb.sh file if you want to know what I mean: it is a shell script which generates a Ruby script, which I think runs a webserver. The shell script generates another shell script to launch the first Ruby script. There is also a bit of Perl, for good measure.

I like the blog post that compares Mercurial and Git with James Bond and MacGyver -- Mercurial is somehow more low-key than Git. It seems to me, that people using Mercurial are not so easily impressed. This is reflected in how each system do what Linus described as "the coolest merge EVER!". In Git you can merge with an unrelated repository by doing:

git fetch <project-to-union-merge>
GIT_INDEX_FILE=.git/tmp-index git-read-tree FETCH_HEAD
GIT_INDEX_FILE=.git/tmp-index git-checkout-cache -a -u
git-update-cache --add -- (GIT_INDEX_FILE=.git/tmp-index git-ls-files)
cp .git/FETCH_HEAD .git/MERGE_HEAD
git commit

Those commands look quite arcane to my eye. In Mercurial we do:

hg pull --force <project-to-union-merge>
hg merge
hg commit

Notice how the Mercurial commands are plain and not special at all -- the only unusual thing is the --force flag to hg pull, which is needed since Mercurial will abort otherwise when you pull from an unrelated repository. It is differences like this that makes Mercurial seem more elegant to me.

Answer 6

I realize this isn't a part of the answer, but on that note, I also think the availability of stable plugins for platforms like NetBeans and Eclipse play a part in which tool is a better fit for the task, or rather, which tool is the best fit for "you". That is, unless you really want to do it the CLI-way.

Both Eclipse (and everything based on it) and NetBeans sometimes have issues with remote file systems (such as SSH) and external updates of files; which is yet another reason why you want whatever you choose to work "seamlessly".

I'm trying to answer this question for myself right now too .. and I've boiled down the candidates to Git or Mercurial .. thank you all for providing useful inputs on this topic without going religious.