What is the difference between update and saveOrUpdate in hibernate?

The important difference between the org. hibernate. Session class methods, save & saveOrUpdate is, save generates a new identifier and results in an INSERT query, whereas saveOrUpdate does an INSERT or an UPDATE. Save method stores an object into the database.

What is difference between update and merge in hibernate?

Hibernate handles persisting any changes to objects in the session when the session is flushed. update can fail if an instance of the object is already in the session. Merge should be used in that case. It merges the changes of the detached object with an object in the session, if it exists.

What does saveOrUpdate return in hibernate?

It returns the id of the entity created. SaveOrUpdate() calls either save() or update() on the basis of identifier exists or not. e.g if identifier does not exist, save() will be called or else update() will be called.

What is the difference between save and update?

The main difference between save and saveOrUpdate method is that save() generates a new identifier and INSERT record into the database while saveOrUpdate can either INSERT or UPDATE based upon the existence of a record.

Is merge faster than insert update?

The basic set-up data is as follows. We’ve purposely set up our source table so that the INSERTs it will do when merged with the target are interleaved with existing records for the first 500,000 rows. These indicate that MERGE took about 28% more CPU and 29% more elapsed time than the equivalent INSERT/UPDATE.

What is detaching Hibernate?

Hibernate will detect any changes made to an object in persistent state and synchronize the state with the database when the unit of work completes. Detached – A detached instance is an object that has been persistent, but its Session has been closed.

How does second level cache works in Hibernate?

Hibernate second level cache uses a common cache for all the session object of a session factory. It is useful if you have multiple session objects from a session factory. SessionFactory holds the second level cache data. It is global for all the session objects and not enabled by default.

Is second level caching is mandatory in Hibernate?

It is a mandatory cache which all entities have to pass. The second-level cache is used to cache object across sessions. For second-level caching, there are some third-party solutions which can be used with Hibernate.

What is the difference between save and saveorupdate in hibernate?

The important difference between the org.hibernate.Session class methods, save & saveOrUpdate is, savegenerates a new identifier and results in an INSERT query, whereas saveOrUpdate does an INSERT or an UPDATE. save Save method stores an object into the database.

What’s the difference between save and session.saveorupdate?

The main difference between Session.save () and Session.saveOrUpdate () method is that save () generates a new identifier and INSERT record into a database while Session.saveOrUpdate () can either INSERT or UPDATE based upon existence of a record.

What’s the difference between save and update in NHibernate?

Save () takes a new object without an identifier and attaches it to the session. The object will be INSERT ‘d. Update () takes an existing object that has an identifier but is not in the session and attaches it to the session. The object will be UPDATE ‘d. SaveOrUpdate () looks at the identifier and decides what is necessary in the above.

When to call save ( ) and saveorupdate ( )?

It returns the id of the entity created. SaveOrUpdate () calls either save () or update () on the basis of identifier exists or not. e.g if identifier does not exist, save () will be called or else update () will be called.