Does anyone know of a useful set of classes to help manage upgrading a particular database schema as you need to push new versions to users? I don't mean the version of the DBMS software, but the actual DB schema that an app accesses.

For example, if v2.0 of MyHibApp adds some columns to one table and changes the type of a column in another, and then v3.0 adds 2 whole new tables, I need a straightforward way to move users from v1.x to v2.0 and then to v3.0. This would involve adding/changing the columns and probably populating existing records with some default values or with values derived from information in the DB already.

I have rolled my own solutions before in C++, but was wondering if anyone had used a good java toolkit that setup a nice structure for you already.

Thanks,

e

In Hibernate 2.x, you can use the generateSchemaUpdateScript method on net.sf.hibernate.tool.hbm2ddl.DatabaseMetadata to determine the deltas (with some degree of accuracy) between your current Hibernate mapping-implied schema and the one your JDBC connection is pointing at. Would this help?

Not a whole lot since I use Hib 3 and I'd like something that didn't require the mapping files (just to be more general) but it's useful to know it's there, thanks. I have a feeling I'll have to pull in little pieces of useful code from a lot of places and roll my own toolkit.

the same is available in Hibernate 3 where we also have a SchemaValidator task that does better reporting.

It is more or less impossible to do automatic conversion of data - something is always "special". The best we can do is to provide tools that reports the differences and a script that needs modificaiton to make work.