I have a project which requires connecting to different RDMS which will have similar Tables/Rows/Datatype but not identical. Has anyone any experience of this? wondering the best way to map entities when the Table name/Column name and Type may differ? Should I use separate config file for each database or will that require twice the maintenance?

There are two very important aspects to keep in mind:

1. Always use incremental migration scripts for each particular database. Use Flyway to manage the schema version updates.
2. You can define the common mappings using annotations, and only override the database-specific mappings using orm.xml configuration files. Check out this article for more details for an example of how you can override a default SEQUENCE identifier with an IDENTITY one for MySQL.

Having a core mapping will allow you to minimize duplication, while still allowing you to diverge one DB from the other.

Hi vlad,

How should we setup transaction management when we need transaction across multiples databases?

Thanks Vlad am trying this out.