Why Your Spring @Transactional Isn’t Rolling Back – MySQL Engine Gotchas

After publishing the "Introduction to Transaction Management" article, a reader reported that adding the @Transactional annotation did not roll back the transaction. After investigation, the cause was identified and is documented here for future reference.

Problem Cause

The missing detail in the earlier example was a crucial configuration property that was not mentioned:

spring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect

The spring.jpa.database-platform setting tells Hibernate which dialect to use. By specifying MySQL5InnoDBDialect, we ensure that when Spring Data JPA creates tables, it uses the InnoDB storage engine. Without this, MySQL defaults to the MyISAM engine, which does not support transactions.

Therefore, if your transaction is not taking effect, check whether the created tables are using the MyISAM engine; if they are, that is the reason.

Besides this, there are many other reasons why a transaction might not work, such as calling a transactional method from within the same class. Those cases are not detailed here, and readers are encouraged to share their own experiences.