Migrax vs Flyway: generated vs hand-written migrations

Flyway and Migrax are both tools that handle database migrations by keeping a series of numbered SQL files. The key difference lies in how they generate those migrations. With Flyway, you manually write every migration, carefully renaming columns and adding new ones. Migrax, on the other hand, watches your JPA entities and automatically generates migrations based on those entity changes, which you then review.

To run a migration, Flyway simply applies the SQL file you've written. However, it doesn't handle any undo or rollback actions automatically - you'd need to write separate undo scripts if you ever need to revert changes. Migrax, by contrast, takes care of writing both the forward migration and a rollback script for you. It also checks for any destructive changes and prevents you from deleting columns without a default value.

Both tools run regular SQL migrations, but Migrax also supports changes to Java entities that can't be expressed through SQL alone. They both maintain a history table for tracking schema changes, and refuse to apply migrations if the checksum of a migration file has changed.

Flyway is a better choice if you're not using JPA entities, don't need database support beyond the 12 relational databases it covers, and prefer a tool with a strong community backing from Redgate. Migrax shines when you're working with JPA entities, need database support for warehouses or document databases like Snowflake and MongoDB, and want an automated rollback feature that handles destructive changes for you.