[news.eclipse.rt.eclipselink] Re: How to upgrade database schema built w

[Enrico <enrico.balatti@xxxxxxxxx>]

Hi MArkus,

I am not sure what do you mean with upgrade...d you mean update your 
schema?If so, what about to use:

<property name="eclipselink.ddl-generation" value="create-tables" />
<property name="eclipselink.ddl-generation.output-mode" value="database"/>


in your persitence.xml file.

This will generate schema when you run your application, basing on 
properties of your entities (if table). As options you can have:

*  none â EclipseLink does not generate DDL; no schema is generated.
* create-tables â EclipseLink will attempt to execute a CREATE TABLE 
SQL for each table. If the table already exists, EclipseLink will follow 
the default behavior of your specific database and JDBC driver 
combination (when a CREATE TABLE SQL is issued for an already existing 
table). In most cases an exception is thrown and the table is not 
created. EclipseLink will then continue with the next statement. (See 
also eclipselink.create-ddl-jdbc-file-name.)
* drop-and-create-tables â EclipseLink will attempt to DROP all tables, 
then CREATE all tables. If any issues are encountered, EclipseLink will 
follow the default behavior of your specific database and JDBC driver 
combination, then continue with the next statement. (See also 
eclipselink.create-ddl-jdbc-file-name and 
eclipselink.drop-ddl-jdbc-file-name.)

BR,
Enrico



Markus Zander ha scritto:
> Hi,
>
> I'm looking for a general solution for upgrading database schema built 
> with EclipseLink. How do you do it in your projects?
>
> The first solution that comes to my mind is to create my own mechanism 
> for upgrading databases, with SQL scripts doing all the work. But in 
> this case I'll have to remember about creating new scripts every time 
> the object mappings are updated. And I'll still have to deal with 
> low-level SQL queries, instead of just defining mappings and allowing 
> the ORM tools to do all the job...
>
> So the question is how to do it properly. Maybe some tools allow for 
> simplifying this task (for example, I heard that Rails have such 
> mechanism built-in).
>
> Thanks for any suggestions.
>
> Markus