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.
If the value is CREATE then the hibernate first drops the existing tables data and structure, then creates new tables and executes the operations on the newly created tables.
You can set spring. jpa. hibernate. ddl-auto explicitly and the standard Hibernate property values are none , validate , update , create-drop .
The spring. jpa. hibernate. ddl-auto takes one of none, validate, update, create, and create-drop. By explicitly specifying one of these options, you are instructing Spring Boot on how to initialize the schema.
From the community documentation:
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
So the list of possible options are,
These options seem intended to be developers tools and not to facilitate any production level databases, you may want to have a look at the following question; Hibernate: hbm2ddl.auto=update in production?
There's also the undocumented value of "none" to disable it entirely.
The configuration property is called hibernate.hbm2ddl.auto
In our development environment we set hibernate.hbm2ddl.auto=create-drop
to drop and create a clean database each time we deploy, so that our database is in a known state.
In theory, you can set hibernate.hbm2ddl.auto=update
to update your database with changes to your model, but I would not trust that on a production database. An earlier version of the documentation said that this was experimental, at least; I do not know the current status.
Therefore, for our production database, do not set hibernate.hbm2ddl.auto
- the default is to make no database changes. Instead, we manually create an SQL DDL update script that applies changes from one version to the next.
First, the possible values for the hbm2ddl
configuration property are the following ones:
none
- No action is performed. The schema will not be generated.create-only
- The database schema will be generated.drop
- The database schema will be dropped.create
- The database schema will be dropped and created afterward.create-drop
- The database schema will be dropped and created afterward. Upon closing the SessionFactory
, the database schema will be dropped.validate
- The database schema will be validated using the entity mappings.update
- The database schema will be updated by comparing the existing database schema with the entity mappings.The hibernate.hbm2ddl.auto="update"
is convenient but less flexible if you plan on adding functions or executing some custom scripts.
So, The most flexible approach is to use Flyway.
However, even if you use Flyway, you can still generate the initial migration script using hbm2ddl.
I would use liquibase for updating your db. hibernate's schema update feature is really only o.k. for a developer while they are developing new features. In a production situation, the db upgrade needs to be handled more carefully.
Although it is quite an old post but as i did some research on the topic so thought of sharing it.
hibernate.hbm2ddl.auto
As per the documentation it can have four valid values:
create | update | validate | create-drop
Following is the explanation of the behaviour shown by these value:
Following are the important points worth noting:
Table not found:<table name>
In case if i give any value to this property(say abc, instead of above four values discussed above) or it is just left blank. It shows following behaviour:
-If schema is not present in the DB:- It creates the schema
-If schema is present in the DB:- update the schema.
hibernate.hbm2ddl.auto
automatically validates and exports DDL to the schema when the sessionFactory is created.
By default, it does not perform any creation or modification automatically on DB. If the user sets one of the below values then it is doing DDL schema changes automatically.
create - doing creating a schema
<entry key="hibernate.hbm2ddl.auto" value="create">
update - updating existing schema
<entry key="hibernate.hbm2ddl.auto" value="update">
validate - validate existing schema
<entry key="hibernate.hbm2ddl.auto" value="validate">
create-drop - create and drop the schema automatically when a session is starts and ends
<entry key="hibernate.hbm2ddl.auto" value="create-drop">
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