&gt; RethinkDB appears to have captured the &quot;MongoDB done right&quot; mindshare<p>Mindshare is irrelevant. MongoDB is killing it in the enterprise right now. They have integration with Oracle, Teradata, Hadoop and countless partnerships with other vendors. You can guarantee MongoDB will still be around in 20 years the way it is positioning itself. Can&#x27;t say the same about RethinkDB (as great as it is).<p>&gt; PostgreSQL has gained JSON and is gaining better replication in order to cover the same niches<p>The PostgreSQL replication story is pretty pathetic given how old&#x2F;mature it is. And I&#x27;ve seen nothing to suggest that anything is really improving in this area. There are a range of addons none of which are supported or built in. Basic replication is confusing, the documentation non existent in parts and good luck getting any support.<p>You compare it to MongoDB (or really any of the newer NoSQL databases) and it&#x27;s like night and day. It takes minutes to setup a replica set and there is plenty of documentation and official support for any issues.