Hibernate hbm2ddl.auto, possible values, and what they do
HibernateOrmPropertiesHbm2ddlHibernate Problem Overview
I am looking at the Hibernate hbm2ddl.auto
configuration property and its possible values:
validate
update
create
create-drop
What do all these values do?
The [Hibernate Reference Documentation][1] only talks briefly about create-drop
, but doesn't say anything about the other values:
> hibernate.hbm2ddl.auto
>
> Automatically validates or exports schema DDL to the database when the SessionFactory
is created. With create-drop
, the database schema will be dropped when the SessionFactory
is closed explicitly.
>
> e.g. validate
| update
| create
| create-drop
I found very useful explanations in these Stack Overflow questions:
- [Hibernate hbm2ddl.auto possible values and what they do?][2]
- [Schema is not dropped on hbmddl.auto = create.drop][3]
But still nothing in the official documentation.
[1]: http://docs.jboss.org/hibernate/stable/orm/manual/en-US/html/ch03.html#configuration-misc-properties "Table 3.7. Miscellaneous Properties" [2]: https://stackoverflow.com/a/1689769/238421 [3]: https://stackoverflow.com/a/6752698/238421
Hibernate Solutions
Solution 1 - Hibernate
For hbm2ddl.auto
property the list of possible options is:
- validate: validate that the schema matches, make no changes to the schema of the database, you probably want this for production.
- update: update the schema to reflect the entities being persisted
- create: creates the schema necessary for your entities, destroying any previous data.
- create-drop: create the schema as in create above, but also drop the schema at the end of the session. This is great in early development or for testing.
Solution 2 - Hibernate
The link you provided is already the official documentation. So, there's nothing more official and comprehensive as-of today.
So I guess the answer to your question is two-fold:
- either file an enhancement request in the Hibernate issue tracker (better with a proposal)
- or read the corresponding code
I know this isn't the perfect answer you dreamt about, but this is actually all you have today.
But the good news is that the project is open-source, so you have all you need to help improve it :-).
Solution 3 - Hibernate
The documentation has been updated to include this information. Here is a link to the official, current documentation for this feature.
> hibernate.hbm2ddl.auto (e.g. none (default value), create-only, drop, > create, create-drop, validate, and update) > > Setting to perform SchemaManagementTool actions automatically as part of the SessionFactory lifecycle. Valid options are defined by the > externalHbm2ddlName value of the Action enum: > > none > No action will be performed. > > create-only > Database creation will be generated. > > drop > Database dropping will be generated. > > create > Database dropping will be generated followed by database creation. > > create-drop > Drop the schema and recreate it on SessionFactory startup. Additionally, drop the schema on SessionFactory shutdown. > > validate > Validate the database schema > > update > Update the database schema