title: Is there a better database than Git (with serializable, immutable, versioned trees)?
body: <p>Imagine the data structure behind Git. It's like a <a href="http://en.wikipedia.org/wiki/Persistent_data_structure" rel="noreferrer">confluently persistent data structure</a>, except using hash references instead of traditional pointers.</p>
  <p>I need Git's data structure, except without any of the working tree and index stuff. And there would be millions of branches, each tracking a handful of other local branches. Commits and merges would occur several thousand times per minute on different threads. Pulls would occur every second.</p>
  <p>Between <a href="http://libgit2.github.com/" rel="noreferrer">libgit2</a> and <a href="http://www.jgit.org/" rel="noreferrer">jgit</a> I can use Git's data storage subsystem.</p>
  <p>But am I using the right tool for the job? Is there a DB that has git's features, but is faster/more concurrent/scalable/less impedance mismatch? Memory-cached writes would be extremely helpful.</p>
  <h3>The task:</h3>
  <p>A <a href="http://weaverengine.com" rel="noreferrer">collaboratively-edited game</a>. Every player has their own branch, and every change they make to the game world is only applied to their version. Changes are merged back into the 'master' branch by trusted users. Data and source code are often tied together, needing the same branching and merging functionality.</p>