Cassandra vs MongoDB - A quick NoSQL DB comparison

In this post, we are going to address some major differences between MongoDB and Apache’s Cassandra, two of the most popular open-source NoSQL database with many powerful features.

1. Quick introduction

Cassandra was built at Facebook then released as open source in 2008. It’s now being managed by The Apache Software Foundation.
MongoDB was built in 2007 by 10gen, which later renamed to MongoDB, Inc. MongoDB, Inc. provides development of the software and sells their enterprise solution.

Before we come down to the differences, let take a look at some points both Cassandra and MongoDB have in common:

They are both NoSQL database.
No ACID compliance.
Both keep recent data in memory to improve performance.
Both data stores discourage joins and prefer denormalization.

2. Feature comparison between Cassandra and MongoDB

	Cassandra	MongoDB
Primary database model	Wide column store	Document store
Supported operating systems	BSD, Linux, OS X, Windows	Linux, OS X, Solaris, Windows
Support of SQL	SQL-like SELECT, DML and DDL statements (CQL)	Read-only SQL queries via the MongoDB Connector for BI
Stored Procedure support	No	Javascript
Triggers support	Yes	No
Replication methods	Selectable replication factor	Master-slave replication
In-memory capabilities	No	Yes
Written language	Java	C++
Protocol	CQL3	Custom binary (BSON)

3. Advantages

Cassandra:

Free of cost
Peer to peer structural design
Elasticity
Fault tolerance
Great Performer
Column based
Adjustable steadiness

MongoDB:

Scalability
Flexibility
User-friendly
No concept of rows and columns
No re-establishment of indexing

4. Disadvantages

Cassandra:

No support to Data Integration
No streaming of globule values.
No cursor support,
Large outputs must be physically paged

MongoDB:

Memory is not expandable
Joins can be done only through multiple queries
No transactions can be done

5. When to use

MongoDB is best for workloads with:

Lots of highly unstructured data.
Evolving data requirements.
Loosely coupled objectives — the design may change by over time.

Cassandra is the best choice for use cases:

SQL-style data types.
Very fast write speeds.
Steep learning curve when switching from SQL.

In short, if you want a database that’s similar to RDBMS but offers more flexibility at the same time, choose Cassandra. If you need a higher degree of flexibility and are willing to learn something new, pick MongoDB.

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