MongoDB is a free and open-source cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with schemas. MongoDB is developed by MongoDB Inc., and is published under a combination of the GNU Affero General Public License and the Apache License. Main features Ad hoc queries MongoDB supports field, range queries, regular expression searches.[8] Queries can return specific fields of documents and also include user-defined JavaScript functions. Queries can also be configured to return a random sample of results of a given size. Indexing Fields in a MongoDB document can be indexed with primary and secondary indices. Replication MongoDB provides high availability with replica sets.[9] A replica set consists of two or more copies of the data. Each replica set member may act in the role of primary or secondary replica at any time. All writes and reads are done on the primary replica by default. Secondary replic...
The MEAN stack is MongoDB, Express.js, AngularJS (or Angular), and Node.js. MEAN applications can be written in one language for both server-side and client-side execution environments.