title: How can I use MongoDB as a cache for Postgresql?
body: <p>I have an application that can not afford to lose data, so Postgresql is my choice for database (ACID) </p>
  
  <p>However, speed and query advantages of MongoDB are very attractive, but based on what I've read so far, MongoDB can report a successful write which may not have gone to disk, so I can't make it my mission critical db (I'll also need transactions) </p>
  
  <p>I've seen references to people using mysql and MongoDB together, one for the transactions and the other for queries. Please not that I'm not talking about keeping some data in one DB and the rest in another. I want to use Postgresql as a gateway to data entry, and MongoDB for reads. </p>
  
  <p>Are there any resources that offer an architecture/guide for Postgresql + MongoDB usage in this way? I can remember seeing this topic in Postgresql conference agenda, but I could not find the link.</p>