Hibernate hbm2ddl.auto update does not drop columns with mysql

Question

Its adds new ones, but as far as I can see it does not drop the old ones?

When I say old ones, I mean properties of entity objects that are now completely removed,where previously they were present and annotated with @column

Are my only options to drop the col manually or change the config value to create ? Neither of which are particularly charming.

Or something else?

Answer 1

For what it's worth, never EVER use hbm2ddl.auto on any live/production database.

Yes, it is "working as intended" that "update" doesn't drop any columns that are not referenced (probably to allow you to use "legacy" databases that have columns that are not used by your hibernate app, but may be used by external applications). However, in certain circumstances, hibernate can drop and recreate columns if, for instance, you change the datatype in your entity. That is one of the reasons you should never use it for any production system.

Personally, I would never trust an automated "black box" framework to handle changes to the datamodel in anything but strictly local/dev environments. I have always set it up so in the local dev environments, you may do create-drop. Once it's time to start promoting your app to central test/stage and then prod, all database changes are done by DBA:s with good old fashioned DDL scripts. Data is far too valuable to risk on a potential bug or unexpected behavior in hibernate (or any other ORM/automated framework). I even make sure that the database user configured in my applications doesn't even have create/drop/alter privileges in the database, just to prevent disasters happening due to bad configuration in hibernate.

So, to answer your question - if you want hibernate to always maintain your database reflecting your entities exactly, "create-drop" is your only option. Just don't ever use it on anything but local dev databases.

Answer 2

I'd have a look into liquibase for keeping your database in sync with your enitities. Maybe a bit of an overkill but well worth it.