Hibernate database specific columnDefinition values

the problem is as follows: We're using hibernate with 开发者_JS百科annotations as O/R Mapper.

Some @Column annotations look like:

@Column(columnDefinition = "longblob", name = "binaryData", nullable = true)

or

@Column(columnDefinition = "mediumtext", name = "remark", nullable = true)

with the columnDefinition attributes being mysql specific

on postgres for example, the columnDefinition values should be "bytea" and "varchar(999999)"

and on oracle probably something else.

Problems arise currently at the time of Schema Export, e.g. when creating the DDL statements.

Possible workarounds that I can think of are - Hack some JDBC driver that does a text replace (e.g. longblob->bytea) for the DDL statements. That's ugly but will work somehow - Use hibernate xml configuration instead of annotations. That will probably work but I prefer annotations

Does anybody know any alternatives? Hibernate specific workarounds are ok, e.g. if the columnDefinition attribute can contain dialect specific values like

@Column(columnDefinition = "mysql->mediumtext, postgres->varchar(999999)", name = "remark", nullable = true)

Thanks Holger

Why don't you use the database-agnostic annotations like:

• @Lob (on a byte[] or a String property)
• @Column(length=90000) (on a String property)

and see what columns will be generated in the database. They will most likely be of the types you want them to be.

Some ideas:

• Use annotation in general, but overload them from Xml in the case where they are specific to your database. Then you can have one configuration file specific to your database.
• Use java Constants in your annotations (they have to be compile-time constants, so you are limited). You can have several sets of Java constants, and point toward the one you want to export to. (Beware, when you point toward another constant, you have to recompile everything.)
• I have also used the dialect to switch some code in my Configuration class. The configuration class receives all data (from annotations or xml), and can then postprocess it.

  For example, I have changed the concatenation symbol from '||' on Oracle to '+' on SqlServer.
  This is conveniently done at runtime :-)