How to cleanly handle source code and data in a repository

Question

I'm working on a collaborative scientific project that is made up by a handful of Python scripts (1M max) and a relatively large dataset (1.5 GB). The datasets are tightly linked to the python scripts since the datasets themselves are the science and the scripts are a simple interface to them.

I'm using Mercurial as my source control tool, but I am not clear on a good mechanism to define the repository. Logistically it makes sense to bundle these together so that by cloning the repository you'd get the entire package. On the other hand, I'm concerned about the source control tool dealing with large amounts of data.

Is there a clean mechanism to handle this?

Answer 1

If the data files change rarely and you normally need all of them anyway, then just add them to Mercurial and be done with it. All your clones will be 1.5 GB, but that is just the way it has to be with that amount of data.

if the data is binary data and changed often, then you might try to avoid downloading all the old data. One way to do this is to use a Subversion subrepository. You will have a .hgsub file with

data = [svn]http://svn.some.edu/me/ourdata

which tells Mercurial to make a svn checkout from the right-hand side URL and put the Subversion working copy into your Mercurial clone as data. Mercurial will maintain an additional file for you called .hgsubstate, in which it records the SVN revision number to checkout for any given Mercurial changeset. By using Subversion like this, you only end up with the latest version of the data on your machine, but Mercurial will know how to get older versions of the data when needed. Please see this guide to subrepositories if you go down this route.