title: Single-file, persistent, sorted key-value store for Java (alternative to Berkeley DB)
body: <p>Berkeley DB (JE) licensing may be a deal killer.  I have a Java application going to a small set of customers but as it is a desktop application, my price cannot support individual instance licensing.</p>
  
  <p><strong>Is there a recommended Java alternative to Berkeley DB?</strong>  Commercial or otherwise (good key-value store implementations can get non-trivial, I prefer to defer maintenance elsewhere).  I need more than just a hash store as I'll need to iterate through subsequent key subsets and basic hash stores would O(m*n) that search and I expect the store to be ~50-60GiB on a desktop machine.  Added benefit anyone that you can recommend that keeps its backing store in a <em>single file</em>?</p>