CockroachDB vs MongoDB: What are the differences?

Introduction

Here, we will discuss the key differences between CockroachDB and MongoDB, two popular databases used in modern web development.

1. Data Model: CockroachDB follows a relational data model, similar to traditional SQL databases. It provides ACID (Atomicity, Consistency, Isolation, and Durability) transactions and supports structured data with tables, rows, and columns. On the other hand, MongoDB follows a document data model, which can store and retrieve complex, hierarchical, and unstructured data in the form of JSON-like documents. It is a NoSQL database.

2. Scalability and Distribution: CockroachDB is designed to be highly scalable and distributed. It uses a distributed architecture that enables automatic data replication and sharding, allowing it to handle large workloads and provide high availability and fault tolerance. MongoDB also supports high scalability, but it is achieved through sharding, which requires manual configuration and management.

3. Consistency Model: CockroachDB provides strong consistency by default, meaning that once a transaction is committed, all subsequent queries will see the updated data. MongoDB, on the other hand, provides eventual consistency by default, where the updates may propagate to different replicas at different times.

4. Query Language: CockroachDB supports SQL as its query language, which is widely known and used by developers. It allows complex queries, joins, and aggregations using familiar SQL syntax. MongoDB uses its own query language called the MongoDB Query Language (MQL), which is designed to work with its document data model. It supports queries with advanced features like geospatial queries and text search.

5. Schema Enforcement: CockroachDB enforces strict schemas for the data it stores, just like traditional SQL databases. All data in a table must conform to the defined schema, ensuring data integrity and consistency. MongoDB is schema-less, allowing flexible and dynamic data structures without strict schema enforcement. It provides greater flexibility for evolving data models but may require additional validation and consistency checks in the application layer.

6. Concurrency Control: CockroachDB uses a distributed concurrency control protocol called Serializability. It ensures that transactions execute in a serial order, preserving consistency. MongoDB, however, uses optimistic concurrency control by default, where conflicts are resolved during updates. It allows multiple concurrent operations but may require additional handling of conflicts in case of simultaneous updates.

In summary, CockroachDB follows a relational data model, provides strong consistency, supports SQL query language, enforces strict schemas, and uses a distributed concurrency control protocol. MongoDB, on the other hand, follows a document data model, provides eventual consistency, uses its own query language (MQL), allows flexible schemas, and uses optimistic concurrency control.