Businesses around the world need databases that can help them manage data. To help these and many other businesses, two databases named PostgreSQL and MySQL were released in June 1989 and May 1995, respectively. Now, both of these databases are relational database management systems meaning they have data stored in row-based table structures. But there are many differences between both.

The first point is that MySQL is used mostly for read-only commands. It's not used when there's a need for concurrency. PostgreSQL, on the other hand, is used in read-write operations. It's also used in big data sets and complex queries. ACID compliance is fully supported in PostgreSQL, whereas in MySQL, some engines don't support ACID. MySQL is cross-platform, whereas PostgreSQL is best used for UNIX-based systems.

Foreign keys are also supported in PostgreSQL but not fully supported in MySQL. Stored procedures, triggers, and even views are fully supported in MySQL, whereas PostgreSQL has materialized views. The triggers in PostgreSQL are also flexible. There's multi-language support in PostgreSQL. SQL data types used in PostgreSQL are diverse and include arrays, hstore.

Now, when is it preferable to use PostgreSQL? Well, businesses that need applications where there's a requirement for write operations and complex queries. However, since the infrastructure of PostgreSQL is complex, newcomers may face difficulty working with it. But the best thing about PostgreSQL is that it has a large community. It also has better performance for write operations with high frequency. But again, since it has fewer tools, it might be challenging for newcomers to get started.

Contrarily, MySQL is best to use when you want to create apps that have few users or apps that don't require frequent data updates and have more read operations. It also works with. Beginners won't have a difficult time building a database using MySQL. This database also performs better in read operations with high frequency.