title: General-purpose databases that never delete or update data in-place
body: <p>I'm very much inspired by the approach to data management <a href="http://www.infoq.com/author/Rich-Hickey" rel="noreferrer">advocated by Rich Hickey</a>, and implemented in <a href="http://www.datomic.com/" rel="noreferrer">Datomic</a>, where the data is never mutated in-place, all the versions are <em>always</em> preserved and query-able, and the time is a first-class concept.</p>
  
  <p>Of course, there are specialized databases matching that description, like Git, or any other source control system. The question is if there are any (more or less) general-purpose DBMS-es of relational, graph, hierarchical, document or any other flavor that can be effectively used in, say, an eCommerce Web application. Or is Datomic the only choice then?</p>