PostgreSQL vs MySQL: 10 Critical Differences You Should Know

MySQL and PostgreSQL are two of the most popular open-source relational database management systems (RDBMS). Both are highly capable and used by many of the world’s largest organizations to handle large volumes of data. However, they cater to different needs and scenarios. Understanding their differences can help you choose the right system for your specific needs.

What is MySQL & PostgreSQL?

MySQL is a popular open-source relational database management system (RDBMS) that uses Structured Query Language (SQL) to access, add, and manage database content. It is widely used for web applications and acts as the database component of the LAMP, WAMP, MAMP, and XAMPP web development stacks, which also include a web server, a programming language, and an operating system. MySQL is maintained by Oracle Corporation, which continues to release updates and improvements regularly.

PostgreSQL, often simply called Postgres, is a powerful, open-source object-relational database system known for its strong reputation for reliability, feature robustness, and performance. It has been actively developed since 1986, originally as part of the POSTGRES project at the University of California, Berkeley. PostgreSQL's advanced features and its ability to handle large volumes of data make it a suitable choice for many types of applications, from small mobile applications to large-scale enterprise systems. It is frequently used in industries that require robust data integrity and regulatory compliance, such as finance and telecommunications.

What is the Difference Between MySQL and PostgreSQL?

MySQL and PostgreSQL are both powerful, open-source relational database management systems, but they have different strengths and characteristics that can make one more suitable than the other for specific applications. Here’s a detailed comparison of the two:

1. Core Architecture and Design

• MySQL: MySQL is known for its flexible storage engine architecture, which allows users to choose from several storage engines (such as InnoDB, MyISAM) depending on their needs—InnoDB for ACID compliance and transaction support, and MyISAM for high read speeds. It provides various replication configurations, including master-slave replication and master-master replication, which are essential for load balancing and high availability.
• PostgreSQL: PostgreSQL is an object-relational database management system (ORDBMS), that allows users to define and create their own custom data types and supports database inheritance, making it more suitable for complex applications. It includes features like table inheritance, function overloading, and foreign keys which ensure data integrity and complex querying capabilities.

2. MySQL vs PostgreSQL Performance

• MySQL: Known for its high performance with read-heavy workloads, MySQL is often chosen for web applications that require speed and efficiency at handling a large number of simple queries.
• PostgreSQL: Excels in handling complex queries and offers better support for concurrent transactions due to its advanced multiversion concurrency control (MVCC). It is often preferred in environments where complex data handling and large-scale database operations are required.

3. Data Types

• MySQL: Supports a broad range of standard SQL numeric, string, and date/time data types. Additionally, it includes some types like ENUM and SET, which are not part of the SQL standard.
• PostgreSQL: Offers a wider array of advanced data types, including geometric/GIS data types, arrays, JSON and JSONB (binary JSON with indexing support), hstore (key-value pair type), and range types. It also allows for creating custom data types.

4. SQL Compliance

• MySQL: Has improved its SQL standard compliance over the years but still lags behind PostgreSQL. Some SQL standard features, like full outer joins or window functions, were added later and might have limitations.
• PostgreSQL: Highly SQL-compliant, it includes support for advanced SQL functionalities like window functions, common table expressions, and full outer joins right out of the box.

5. Replication and High Availability

• MySQL: Offers various types of replication configurations (e.g., master-slave replication, master-master replication) which are relatively easy to set up and manage.
• PostgreSQL: Also supports multiple forms of replication (including logical and streaming replication) and is considered to have more flexible and robust replication features. Its approach to replication and data integrity is more sophisticated, suitable for enterprise-grade solutions.

6. Extensibility and Customization

• MySQL: Allows custom storage engines, plugins, and other extensions. Users can choose between different engines for each table, depending on the need (e.g., InnoDB for transaction support and ACID compliance, MyISAM for high-speed storage without transactions).
• PostgreSQL: Highly extensible, it supports the creation of user-defined functions and data types, custom operators, and even allows code to be written in various programming languages directly within the database (e.g., PL/Python, PL/Java).

7. Community and Support

• MySQL: Since being acquired by Oracle, there have been concerns about its open-source nature. However, it still retains a large community and broad industry support. Variants like MariaDB continue the original open-source spirit of MySQL.
• PostgreSQL: Has a very strong and active community, which is purely open-source and often praised for its innovation and independent development path.

8. Licensing

• MySQL: Uses the GPL (General Public License), which can be restrictive for commercial software developers who do not want to open their source code. Commercial licenses need to be purchased for proprietary use.
• PostgreSQL: Uses the PostgreSQL License, a liberal open-source license, similar to the MIT or BSD licenses, which imposes very few restrictions on how and where it can be used.

9. Popularity in Different Sectors

• MySQL: Widely used in web applications and is part of the popular LAMP (Linux, Apache, MySQL, PHP/Python/Perl) stack. It’s favored by companies needing a reliable, high-performance database without the complexity of more robust systems.
• PostgreSQL: Often preferred in academic, research, and large systems requiring robust data handling capabilities and compliance with traditional database standards. It's favored in industries where data integrity and standards compliance are crucial.

PostgreSQL vs MySQL Syntax

1. String Concatenation

MySQL: Uses the CONCAT() function:

SELECT CONCAT('Hello', ', ', 'World!');

PostgreSQL: Uses the || operator:

SELECT 'Hello' || ', ' || 'World!';

2. Case Sensitivity and Quoting

MySQL: SQL keywords are case-insensitive. Identifiers like column and table names are case-insensitive on Windows, and case-sensitive on most Unix platforms by default. Backticks are used to escape identifiers:

SELECT `column` FROM `table`;

PostgreSQL: SQL keywords are also case-insensitive. However, identifiers are case-sensitive unless double quotes are used:

SELECT "column" FROM "table";

3. Auto-incrementing Primary Keys

• MySQL: Uses the AUTO_INCREMENT keyword:

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(255));

PostgreSQL: Uses the SERIAL pseudo-type or BIGSERIAL for larger ranges:

CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    username VARCHAR(255));

Functions and Operators

Date and Time Functions: There are significant differences in how dates and times are manipulated.

• MySQL:

SELECT DATE_ADD('2023-01-01', INTERVAL 1 DAY);

• PostgreSQL:

SELECT '2023-01-01'::date + INTERVAL '1 day';

• Regular Expressions: MySQL uses REGEXP or RLIKE, while PostgreSQL uses , *, !, and !* for regex operations.

Check out our free SQL tutorial for beginners and experiment with our online SQL Editor to enhance your skills!

MySQL vs PostgreSQL Difference in Tabular Format

Read our latest blog “Difference Between SQL and MySQL”

Conclusion

The choice between MySQL and PostgreSQL depends heavily on specific project requirements. If you need a database that is easy to set up and use, with great performance under read-heavy loads, MySQL might be the way to go. However, if you are looking for advanced features, complex data handling, and strong compliance with SQL standards, PostgreSQL could be a better fit.

Both databases are powerful tools with strong communities, and your decision should be based on the specific needs of your application. By understanding their differences and evaluating your needs, you can select the most suitable database management system for your project.