So from a DBA POV, what is mongo then? To begin with, there is no SQL interface and no “query language” per se, rather to the user, MongoDB looks a lot like a Java Script environment with a lot of space for variables, sort of. MongoDB has databases, and in databases there are collections, which are sort of like tables in an RDBMS. A collection is a key-value store, you can define a key for the collection, or MongoDB will generate one for you. MongoDB is schemaless, which means that a collection doesn’t not have any predefined columns or anything. Instead, if an object that you store has an attribute foo then you assign a value to it in your object and insert the object. That’s it. And you can have an index on foo if you want to. And index in this case is a traditional B-Tree index, nothing more exciting than that.
What I didn’t find in these posts is some references to the not so obvious differences between MySQL and MongoDB (e.g. indexing, disk access, etc.).
Original title and link: MongoDB for MySQL People ( ©myNoSQL)