Hello, I'm developing an application using JBoss 4.2.3 (and hence Hibernate 3). I have to store some XML documents in a database and I have to read, and update them. These documents will be encrypted eventually so I have defined an entity like this:

@Entity
public abstract class Document<T> implements Serializable {

@Id
@GeneratedValue
protected long id;

@Lob
protected byte[] content;

protected String username;

....................
getters and setters
....................
}

I'm using PostgreSQL as my backend.

Hibernate generates a table for this entity with a field of type 'oid' for the row content and it stores the real content in the common table pg_largeobjects. The problem is that, everytime that I update the field content, it generates a new entry in pg_largeobjects and updates the oid field but it does not delete the old object, so in every update to my document, I get a new copy of all the content in the database.

Is this the normal behavior? I'd like to either, use the same record for the update or to generate a new one, but delete the old one, since it's no longer needed.

I'm not an expert, but AFAIK this is "normal". So if you delete a row, which has a BLOB with an OID, the corresponding TOAST structures and data won't be deleted. You have to take care of this yourself AFAIK. Search for lo_manage manage function and triggers on google to get more info on that. Currently I'm trying to define the triggers, but I experience problems during persist:
https://forum.hibernate.org/viewtopic.php?f=1&t=1005584