MYSQL is not suitable for transaction, POSTGRESQL is

MySQL was built for speed, to the detriment of everything else. SQL standard features like transactions, referential integrity and others have been grafted over only after considerable arm twisting.

However, it is only fast at low concurrency levels, and reports of instability, low robustness and scalability keep coming out.

PostgreSQL was built strictly following the ACID model, with an emphasis on data integrity and SQL standard compliance, speed notwithstanding. It then underwent optimizations and speedups, while at the same time adding new features to its already large set.

Today it is robust, standards compliant and well featured. While still being relatively slow at low concurrency levels, it scales well with increasing load levels