Disclaimer: I used to work for MongoDB, but left more than 2 years ago.
I'm really happy to see the free tier as an option - I was a big fan, user, and advocate of MMS back when that was a free option for monitoring, and accessibility to Atlas has been lacking a "try before you buy" option (though I did pick up free credit from the MongoDB booth in Re:Invent, it makes it hard to recommend to others).
Also great to see an official utility for migrations with MongoMirror too. These things, along with the Jepsen tests now being in CI (and passing in 3.4) seemed so far away when I left MongoDB, really great to see them come to fruition :)
Having had the pleasure to know and work with William, I think he would be chuffed with the existence of the award, though probably a little embarrassed to have it named after him which only makes it more appropriate.
It's a perfect tribute to him and I can't wait to see who wins the first one :)
2.4 introduced text indexes for full text search as a beta, and 2.6 finishes the job of fully integrating them into the product - they are fully supported with the new release (including in the aggregation framework).
In terms of how they compare, I'm not familiar enough with Elasticsearch to comment, but for basic test searching needs, the implementation in MongoDB is pretty decent. More here:
Just to note, the MongoDB journal is basically a write ahead log and has been around since 1.8. It's not simple, you are correct, and involved remapping portions of memory privately, and leads to some inflated numbers on the virtual memory reporting side. There's a great write up here:
It doesn't use mmap for locking though - and in any case one database is already multiple files (2GB max). There are internal data structures used by MongoDB and the database itself takes care of locking, mmap just gets the data into memory.
Just to clarify on positive/negative limits on a cursor: if the limit number is negative, then the database will return that number of results and close the cursor. No further results for that query can be fetched. If the limit is positive you can leave the cursor open to receive further results, hence the option for both. (see http://stackoverflow.com/a/11995057/1148648)
The 2nd Edition of the MongoDB: The Definitive Guide from O'Reilly is one I can recommend (full disclosure: I was a technical reviewer on that edition). http://shop.oreilly.com/product/0636920028031.do
Finally, there are free MongoDB courses available at http://education.mongodb.com in various flavors of programming language, as well as an ops/DBA focused course.
I'm really happy to see the free tier as an option - I was a big fan, user, and advocate of MMS back when that was a free option for monitoring, and accessibility to Atlas has been lacking a "try before you buy" option (though I did pick up free credit from the MongoDB booth in Re:Invent, it makes it hard to recommend to others).
Also great to see an official utility for migrations with MongoMirror too. These things, along with the Jepsen tests now being in CI (and passing in 3.4) seemed so far away when I left MongoDB, really great to see them come to fruition :)