title: What choices for a relational Document-store (NoSql?) database engine?
body: <p>What choices are there for document-store databases that allow for relational data to be retrieved? To give a real example, say you have a database to store blog posts. I'd like to have the data look something like:<br>
  <code>{id: 12345,<br>
   title: "My post",<br>
   body: "The body of my post",<br>
   author: {<br>
        id: 123,<br>
        name: "Joe Bloggs",<br>
        email: "joe.bloggs@example.com"<br>
   }<br>
  }</code></p>
  
  <p>Now, you will likely have a number of these records that all share the author details. What I'd really like is to have the author itself stored as a different record in the database, so that if you update this one record every post record that links to it gets the updates as well. To date the only way I've seen mentioned to do this is to have the post record instead store an ID of the author record, so that the calling code will have to make two queries of the data store - one for the post and another for the author ID that is linked to the post. </p>
  
  <p>Are there any document store databases that will allow me to make a single query and return a structured document containing the linked records? And preferably allow me to edit an internal part of the document, persist the document as a whole and have the correct thing happen [I.e. in the above, if I retrieved the entire document, changed the value of email and persisted the entire document then the email address of the author record is changed, and reflected in all posts that have that author...]</p>