MonoDB is a NoSQL (Not Only SQL) document style database with a query engine to view the stored data.

About MongoDB

• Mongo have a database, which are similar to Oracle schemas
• A database have one or more collections, which are similar to tables in RDBMS
• A Collection can have one or more documents, which are similar to rows in RDBMS
• A document is made up of one or more fields, which are similar to columns in RDBMS
• You can create indexes like RDBMS for fast query performance
• Query results are stored in cursors
• MongoDB have query selector which are similar to where clause in SQL of RDBMS, these selectors are JSON objects
• Update statement takes two argument first selector and then $set value
• No joins can be used like SQL as this database is document style
• Arrays are supported as well as embedded documents
• De-normalization model is most common model

When to use MongoDB

• Schema-less database is required
• Writes: You can send write command and it writes without wait, so if faster write is required
• Journaling: You can control the write behavior
• Durability: Mongo have self healing cluster environment with minimal or no DBA required
• Full Text Search
• Geospatial: Mongo allows you to store x and y co-ordinates with document and then you can use find to find near by or with in circle documents
• Tools and Maturity: this is relatively new database compare to RDBMS however it is widely used and good community support
• Data Processing: Can be done using Map Reduce. It also has some basic aggregation