PostgreSQL vs MySQL: 10 Critical Differences You Should Know

Irshad Khan / 2 weeks
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9 min read

10 Differences
JSON
MySQL
PostgreSQL
RDBMS

When it comes to selecting a relational database management system (RDBMS) for your application, two of the most popular options are PostgreSQL and MySQL. Both are open-source and widely used in the development community, but they come with distinct features, performance characteristics, and use cases. Understanding the key differences between them can help you make an informed decision for your project.

PostgreSQL and MySQL are both widely used open-source relational database management systems (RDBMS), but they have key differences in features, performance, and use cases.

PostgreSQL is known for its advanced features and SQL compliance. It is often favored for complex applications that require data integrity, transactions, and support for custom data types. It is fully ACID-compliant and offers rich features like JSONB, full-text search, and window functions. PostgreSQL is highly extensible, allowing developers to create custom functions, types, and indexes, making it ideal for data-heavy applications, data warehousing, and geospatial systems.

1. Database Features and SQL Compliance

PostgreSQL: Known for its advanced SQL compliance, PostgreSQL supports many advanced features such as full ACID compliance, transactions, complex queries, and user-defined types. It is highly extensible and supports custom functions, triggers, and stored procedures. PostgreSQL follows the SQL standard more closely and includes sophisticated data types like JSONB, HSTORE, and arrays.

MySQL: While MySQL also supports ACID compliance with the InnoDB engine, it is often seen as less strict in terms of SQL compliance. MySQL supports fewer advanced features compared to PostgreSQL, and while it’s great for simple queries and high-speed read-heavy workloads, it can fall short in more complex database needs.

2. Performance Optimization

PostgreSQL: Optimized for complex queries, concurrent processing, and transaction-intensive workloads. It supports parallel query execution and has intelligent query planning with better indexing for complex operations.
MySQL: Known for faster performance in read-heavy operations and simple queries. Optimized for fast reads, replication, and sharding, making it ideal for web-based apps with high throughput.

3. ACID Compliance & Transactions

PostgreSQL: Fully ACID-compliant with support for MVCC (Multiversion Concurrency Control), offering high isolation without locking the database.
MySQL: The InnoDB engine supports ACID compliance but lacks some advanced concurrency mechanisms, leading to lower isolation in some setups.

4. Data Integrity and Constraints

PostgreSQL: Strong focus on data integrity with support for foreign keys, check constraints, partial indexes, and domain types for custom validations.
MySQL: Basic support for foreign keys and constraints, but lacks extensive check constraints and flexibility in defining custom validations.

5. Support for JSON Data

PostgreSQL: Offers robust JSON support with JSONB and JSON types. JSONB supports indexed storage and fast querying of JSON data.
MySQL: Introduced JSON support in version 5.7. However, its capabilities are limited, treating JSON as a string and offering basic manipulation functions.

6. Replication and Clustering

PostgreSQL: Supports synchronous, asynchronous, and logical replication. Clustering is available via extensions like Patroni, Citus, or third-party tools.
MySQL: Built-in support for master-slave, master-master, Group Replication, and MySQL Cluster. Easier to set up and manage for large-scale replication needs.

7. Licensing and Open-Source Model

PostgreSQL: Released under the PostgreSQL License, offering full freedom for commercial use, distribution, and modification.
MySQL: Uses the GPL license, which may require open-sourcing derivative works. Commercial version available via Oracle with additional features.

8. Community and Ecosystem

PostgreSQL: Large, active community with strong documentation, a wide range of tools, and continuous development through open contribution.
MySQL: Supported by Oracle with a vast user base. Some concerns about Oracle’s control affecting the pace of open-source development.

9. Scalability

PostgreSQL: Highly scalable with partitioning and replication. Requires extensions like Citus for horizontal scaling at large scale.
MySQL: More scalable out-of-the-box for web apps using read replicas, sharding, and multi-master setups. Favored by startups and fast-growing apps.

10. Syntax Comparison

String Concatenation:
PostgreSQL: SELECT 'Hello' || ' ' || 'World';
MySQL: SELECT CONCAT('Hello', ' ', 'World');
Auto-Increment:
PostgreSQL: CREATE TABLE users (id SERIAL PRIMARY KEY);
MySQL: CREATE TABLE users (id INT AUTO_INCREMENT PRIMARY KEY);
Boolean Data Type:
PostgreSQL: CREATE TABLE users (active BOOLEAN);
MySQL: CREATE TABLE users (active TINYINT(1));

✅ Conclusion

Choosing between PostgreSQL and MySQL depends on your project’s complexity, scalability needs, and performance requirements. PostgreSQL is ideal for complex queries, large datasets, and high-concurrency workloads. MySQL is better suited for simpler, read-heavy applications.

Consider aspects such as data structure, licensing, ecosystem, and developer experience. Understanding these 10 key differences will help you make the best choice for your specific application needs.

Both frameworks are excellent choices—select the one that aligns best with your goals and development workflow.

📚 FREQUENTLY ASKED QUESTIONS (FAQs)

1️⃣ What is the main difference between PostgreSQL and MySQL?

PostgreSQL is an advanced, object-relational database system with support for complex queries, custom data types, and full ACID compliance. MySQL is known for its speed and simplicity, making it suitable for read-heavy web applications. PostgreSQL is feature-rich, while MySQL prioritizes performance.

2️⃣ Which is better for performance: PostgreSQL or MySQL?

For read-heavy workloads, MySQL tends to perform better, especially in simple query scenarios. PostgreSQL excels in complex queries, transactions, and write-heavy applications, where advanced indexing and optimization techniques come into play.

3️⃣ Do both support ACID transactions?

Yes, both PostgreSQL and MySQL support ACID transactions. PostgreSQL provides robust support for complex transactions, while MySQL’s InnoDB engine offers ACID compliance, although PostgreSQL has more advanced transaction management features.

4️⃣ Which is better for scalability?

MySQL is often preferred for its ability to scale horizontally with replication and sharding techniques, making it suitable for web applications that need high availability and distribution. PostgreSQL can scale but often requires third-party tools for better horizontal scaling.

5️⃣ What are the licensing differences between PostgreSQL and MySQL?

PostgreSQL uses a permissive open-source license (PostgreSQL License), allowing free modification and commercial use. MySQL is licensed under GPL (General Public License), which may require you to release source code for derivative works if distributed, although a commercial license is available through Oracle.

6️⃣ Can I use PostgreSQL for web applications like MySQL?

Yes, PostgreSQL can be used for web applications, especially those requiring complex data types, advanced queries, and high levels of consistency. MySQL is more commonly used in content management systems and e-commerce websites due to its simplicity and speed in handling basic operations.

7️⃣ Which database is better for handling large amounts of data?

PostgreSQL is better suited for large, complex datasets due to its support for advanced indexing, full-text search, and geospatial data types. It is ideal for big data and analytical workloads. MySQL can also handle large datasets but may face performance issues in complex query environments.

8️⃣ How do they differ in handling JSON data?

PostgreSQL has strong support for JSON with the JSONB type, enabling fast queries and indexing of JSON data. MySQL also supports JSON, but its functionality is more limited compared to PostgreSQL, with fewer advanced indexing and querying capabilities.

9️⃣ Are there differences in SQL syntax between PostgreSQL and MySQL?

Yes, while both are SQL-based, there are syntax differences, such as string concatenation (|| in PostgreSQL vs CONCAT() in MySQL), auto-increment fields (SERIAL in PostgreSQL vs AUTO_INCREMENT in MySQL), and how limits and offsets are used in queries.

🔟 Which is easier to learn, PostgreSQL or MySQL?

MySQL is generally considered easier to learn for beginners due to its simplicity, widely available tutorials, and user-friendly setup. PostgreSQL, with its advanced features and complexity, may have a steeper learning curve but offers more power for complex applications once mastered.

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