An introduction and justification of why we're moving away from SVN and towards mercurial.

1. Getting in touch with your Mercurial side:
How you’ll be happier, more productive,
and less ragey.
Adam Pah
With contributions from:
Dan McClary
Irmak Sirer
Monday, January 28, 13 1

2. So what is Mercurial?
• Mercurial is a Distributed Version Control System (DVCS)
• Mercurial (along with Git and Bazaar) is a part of the next generation version
control systems
• These systems have been designed to address problems, annoyances, and
failings in SVN
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3. So why are we switching?
• SVN is frustrating when you try to use it in a more advanced fashion or in a
large collaboration.
• Sometimes it’s just frustrating when it’s only you.
• SVN is slow once repositories get large.
• This leads to using it less or only once a stopping point in the work is
reached, defeating the purpose of version control.
• SVN is not smart.
• SVN could not merge it’s way out of a paper bag, let alone keep track of
constantly changing files.
• Did I mention that SVN is frustrating?
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4. Differences between SVN and Mercurial: Paradigm
SVN
Source: http://www.hginit.com
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5. Differences between SVN and Mercurial: Paradigm
Mercurial
Source: http://www.hginit.com
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6. Differences: Nitty Gritty
• SVN keeps revisions of each commit
• Mercurial keeps changesets at each commit
• So what is the difference?
• If you and I were both working on the same repository, we both makes lots
of changes and go our own way.
• When we inevitably have to put everything back together SVN looks at the
both of our last revisions and tries to mash them together.
• This typically does not work.
• Mercurial keeps track of every change in each file.
• When we merge back together it just sums all the changes in the
changesets on its own and applies them the best it can.
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7. Differences: Nitty Gritty
• But wait a minute!!!!
Merging is the devil!
SVN taught me that over and over again.
• Mercurial is different, it accepts merging and does it intelligently.
• This is for two main reasons:
• Keeping track of changesets is one integral reason, it has more of an idea
what has changed
• Separating commits from pushing to others forces it to have a more robust
tool set to merge.
Branching and merging are the common tools of a Mercurial workflow.
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8. Mercurial Workflows
All alone
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9. Mercurial Workflows
Anarchy
Irmak Adam Dan
Monday, January 28, 13 9

10. Mercurial Workflows
Centralized Store
Text
Irmak Dan
Adam
Monday, January 28, 13 10

11. A config all to myself
• Just like vi or emacs, mercurial has a configuration file in your home directory
• You can edit this file at ~/.hgrc
• You will need to set your username and e-mail in it
(Mercurial won’t work without it)
• You can also enable new extensions in this file, such as hg fetch or hg
convert
Monday, January 28, 13 11