MongoDB Vs SQL Server - Key Differences

September 30, 2024
20 min read

Choosing the right database for your application is essential for achieving the best performance. As the amount of data continues to grow, finding effective and dependable storage solutions is extremely important. Two popular options that developers and businesses often consider are Microsoft SQL Server, a strong relational database management system, and MongoDB, a prominent non-relational database.

Both databases offer unique features and capabilities that cater to specific use cases. In this article, you'll explore a holistic comparison of MongoDB vs. SQL Server, which enables you to make an informed decision that aligns with your project's goals and requirements.

MongoDB Overview

MongoDB

MongoDB is a versatile NoSQL, document-oriented database that enables you to store data in JSON-like documents. It supports horizontal scaling through sharding, where large datasets are distributed across multiple servers or clusters. Due to its scalable architecture and efficient data storage mechanisms, MongoDB provides high performance, handling large volumes of data and high-throughput operations effectively.

Key Features of MongoDB

Here are some of the key features of MongoDB:

  • GridFS: It is a MongoDB specification that is useful for storing files that are larger than 16 MB. GridFS divides large files into smaller chunks and stores them in a collection for efficient storage and retrieval operations.
  • Indexing: MongoDB supports various primary and secondary fields to improve the speed of queries. It allows indexing on any field in a document, including those nested within arrays, ensuring that database operations are always optimized for performance.
  • Change Streams: Change Streams in MongoDB are real-time streams of database changes that flow from the database to your application. This enables applications to react instantly to data changes across a single collection, a database, or an entire deployment.

SQL Server Overview

SQL Server

MS SQL Server is a versatile relational database management system that caters to various applications, such as transaction processing, business intelligence, and advanced analytics. At its core lies the Database Engine, which manages data storage and security. This engine offers controlled access and fast transaction processing to meet the needs of the data-consuming applications in your enterprise.

Key Features of SQL Server

Here are some of the key features of SQL Server:

  • Data Compression: Reduces the amount of space required to store data, improving performance and storage efficiency by compressing tables and indexes.
  • PolyBase: This is a data virtualization feature that enables you to query data from external sources as if it were local to the SQL Server instance. For example, you can access data from sources such as Oracle, Hadoop clusters, and CosmosDB without moving the data into SQL Server.
  • Temporal Tables: These are system-versioned user tables that automatically record data changes over time. This facilitates time-based querying of data for auditing or historical analysis.

MongoDB Vs SQL Server

With 24.8% of developers using MongoDB and 25.3% relying on SQL Server, both databases remain highly competitive, offering unique capabilities tailored to different use cases. Let's take a closer look at the key differences between MongoDB vs SQL Server.

Schema Model

MongoDB has a flexible schema model where documents in a collection are not required to have the same fields or data types by default. This flexibility lets you easily adapt the data model to changing requirements without restructuring your entire database. However, if you want to enforce consistency at a specific point, you can also apply schema validation rules to your collections.

In contrast, SQL Server enforces a strict schema model, requiring you to define the schema before you insert any data. This approach ensures that all incoming data is checked against the predefined rules, and if something doesn’t fit the schema, SQL Server will show an error. While this helps maintain data consistency, you find it challenging to dynamically classify and store the hierarchical data.

Indexing

Indexes in MongoDB improve query efficiency by limiting the number of documents scanned. If an index matches a query, MongoDB uses it instead of scanning the entire collection. MongoDB provides various index types like single field, compound, multikey, and geospatial. By default, it creates a unique index on the _id field while creating a collection to prevent duplicate values. However, creating too many indexes in MongoDB can slow down write operations, as each write must update all relevant indexes.

On the other hand, in SQL Server, an index contains keys from one or more columns in a table. There are two main index types—clustered, which sorts and stores data by key values, and nonclustered, which holds indexed columns with pointers to rows. Unlike MongoDB, which automatically creates an index on the _id field in every collection, SQL Server sets indexes only when constraints are defined.

For example, when you create a table with a UNIQUE constraint, the Database Engine automatically creates a nonclustered index, whereas a clustered index is created for a PRIMARY KEY.

Query Language

MongoDB Query Language (MQL) is used to query data in MongoDB. It offers an intuitive way to handle complex data workloads for any data type, including geospatial, array, and time series data. MQL has the same syntax as documents, making it easy to use for even advanced querying. You can use operators like $lookup and $unionWith to join multiple collections easily. MQL offers you great flexibility as you can use it from the command line interface (CLI), development drivers, or Visual Studio Code.

Conversely, SQL Server uses Transact-SQL (T-SQL) as its query language, a procedural language that adds proprietary extensions to the standard SQL query language. With T-SQL, you can effectively run complex operations like joining tables, aggregating data, and analytical queries. While T-SQL is powerful for structured data management, it can be less flexible than MongoDB's MQL when dealing with unstructured or semi-structured data.

Replication

Data replication in MongoDB enhances redundancy and data availability through the use of replica sets, which maintain identical copies of data. The primary server handles all write operations, replicating these changes to secondary servers. If the primary server experiences a critical failure, a secondary server can be elected as the new primary. When the former primary returns online, it automatically becomes a secondary server for the new primary node.

On the other hand, SQL Server provides a robust system for data synchronization across databases using three different types of replication. Transactional replication is ideal for high-throughput needs and is used in server-to-server scenarios. Merge replication is designed for mobile and distributed applications where data conflicts may occur. Furthermore, snapshot replication provides an initial data set for transactional and merge replication or can also be used when complete data refreshes are appropriate. 

Security

MongoDB offers a wide range of security features to protect data, including authentication, role-based access controls, and robust encryption. Salted Challenge Response Authentication Mechanism (SCRAM) is MongoDB's default authentication mechanism. When users authenticate themselves, MongoDB uses SCRAM to validate their credentials against the authentication database. Furthermore, it supports TLS/SSL (Transport Layer Security/Secure Sockets Layer) to encrypt the network traffic.

On the flip side, SQL Server incorporates a comprehensive security framework to protect data at various levels. It primarily supports two authentication modes—Windows authentication and SQL Server and Windows Authentication (mixed mode). Additionally, it offers various encryption techniques such as Transparent Data Encryption (TDE) and Always Encrypted. To further enhance security, you can use Row-Level Security (RLS) with Always Encrypted or Dynamic Data Masking (DDM).

MongoDB Vs SQL Server: A Quick Comparison

Below are the key differences between MongoDB and SQL Server at a glance:

Aspect
MongoDB
SQL Server

Database Type

NoSQL, Document-oriented database.

Relational Database Management System (RDBMS).

Schema Model Dynamic (Flexible Schema). Fixed Schema.
Data Storage Format BSON (Binary JSON). Tables (Rows & Columns).
Query Language MongoDB Query Language (MQL). Transact-SQL.
Default Isolation Level Read Uncommitted. Read Committed.
Cloud Ecosystem AWS, Azure, and Google Cloud. Microsoft Azure.
Scalability Horizontal. Vertical.
Performance Optimized for read-heavy workloads with high flexibility. Optimized for complex transactions.
Availability Replica sets for high availability and redundancy. Always On Availability Groups, mirroring, and log shipping for high availability.
Integration Support High integration with Big Data ecosystems (Hadoop, Spark, etc.). Strong integration with Microsoft ecosystem.
Programming Languages

Supports C, C++, C#, Go, Java, Node.js, PHP, Ruby, Python, Rust, Scala, Swift, Kotlin, etc.

Supports C, C++, Java, Python, PHP, R etc.
Learning Curve Easier for developers familiar with JavaScript or JSON. Familiar to those with experience in relational databases and traditional SQL.

Factors to Consider When Choosing MongoDB or SQL Server

Here are a few factors to consider in choosing between Microsoft SQL Server vs MongoDB:

Data Model Flexibility

If your data is highly structured and follows a predefined schema, SQL Server may be a better fit as it is ideal for handling relational data with defined tables and columns. However, if your data is unstructured and schema-less, MongoDB's document-oriented model may be more suitable, as it offers greater flexibility in data storage and schema changes.

Deployment Flexibility

MongoDB is open-source and offers significant deployment flexibility. With the MongoDB Community Edition, you can self-manage and host it locally or in the cloud. On the other hand,  SQL Server, while traditionally associated with on-premise installations, has evolved to offer a variety of deployment options as well. It can run in the cloud via Azure SQL Database. 

Reliability and Availability

Both databases offer features for ensuring high availability, but they differ in their underlying approaches. SQL Server follows the ACID (Atomicity, Consistency, Isolation, Durability) principles, focusing on transaction reliability. MongoDB is built on the CAP (Consistency, Availability, Partition tolerance) theorem, prioritizing data availability over strict consistency.

Performance

If your application handles a high volume of reads and writes in a distributed environment, MongoDB often performs better, especially for large datasets with frequent updates. However, if you need strong consistency and transactional support, SQL Server is more appropriate, as it guarantees data accuracy across transactions.

Query and Analytics

SQL Server provides a powerful, SQL-based query language that is well-suited for complex analytical queries and joins across multiple tables. MongoDB's query language is more limited, particularly when handling complex joins and duplicate field names. Though MongoDB's aggregation pipelines support basic analytics, they are less efficient for intricate queries, making SQL Server a better option for advanced querying needs.

Streamline Data Integration into MongoDB or SQL Server Using Airbyte

Airbyte

By now, you've understood the key aspects to be considered in MongoDB vs SQL Server performance. However, regardless of the database you choose, you need to properly integrate data from all your sources into the chosen database to gain a holistic view of your business operations. As your data is scattered across various platforms like CRMs, social media platforms, etc., you need a data integration platform to consolidate all this data into your destination system.

Airbyte is one such data movement and replication platform. It helps you extract data from various sources and load it into the destination of your choice. Additionally, its easy-to-use interface helps you quickly load data from MongoDB to MS SQL Server or vice versa without extensive coding.

Here are some of the key features of Airbyte:

  • Pre-built Connectors: Airbyte offers an extensive library of over 400+ pre-built connectors, enabling you to connect and synchronize data from multiple sources effortlessly. Furthermore, it offers the flexibility to build your own custom connector using the Connector Development Kit (CDK) in less than 30 minutes.
  • Vector Store Integration: Airbyte empowers you to directly load your unstructured data into popular vector store destinations like Milvus, Pinecone, and Weaviate. This helps you streamline the process of preparing your data for AI and machine learning applications.
  • CDC: With Airbyte's Change Data Capture (CDC) technique, you can capture and synchronize data modifications from source systems. This confirms that the target system is constantly updated with the latest changes.

Wrapping It Up

This article offered a detailed comparison of MongoDB vs SQL Server performance. Both databases come with unique features and capabilities, making them suitable for different scenarios. MongoDB is ideal for applications requiring flexible schema design and high scalability.

On the flip side, MS SQL Server works well for transactional workloads and complex querying, making it a solid choice for enterprise applications with strong data consistency requirements.

Limitless data movement with free Alpha and Beta connectors
Introducing: our Free Connector Program
The data movement infrastructure for the modern data teams.
Try a 14-day free trial