Hibernate is a strong object-relational mapping (ORM) framework for Java developers. It provides a collection of general-purpose, high-level query methods
Select the Model Repository Service in the Domain Navigator.
Select the Processes tab.
In the Repository Performance Properties section, click Edit.
The dialog box Edit Repository Performance Properties displays.
Increase the Cache JVM Options parameter's value.
Click the OK button.
Hibernate Save vs Persist
Key
save()
persist()
Basic
It keeps track of objects in a database.
It also keeps track of objects in a database.
Return type
The save () method's return type is a serializable object.
The persist () method has a void return type.
Transaction Boundaries
It can save objects both within and outside of boundaries.
It can only save objects that are within the transaction's boundaries.
Assigning of identifier value
The save() method enables the quick assignment of an identifier value.
The persist() method does not promptly ensure that an identifier value is assigned to a persistent state.
Detached Object
For detached objects, it will add a new row to the table.
For detached objects, it will throw a persistence exception.
Execution of insert query
The save() method returns an identifier intending to execute an insert query immediately to get the identification. It makes no difference whether the transaction is outside or inside.
If an insert query is placed outside the transaction boundaries, the persist() method fails to perform it.
Supported by
Hibernate is the only framework that supports it.
JPA is also in support of it.
Utility
The save approach is less useful in a long-running conversation that has expanded a Session context.
The persist method is used in long-running discussions that provide an extended Session context since it is called outside transaction boundaries.
getCurrentSession Hibernate Example
Hibernate handles flushing and closing session objects internally, so programmers don't have to.
It is faster than openSession() in a single threaded environment.
Otherwise, an exception will be thrown until you define extra properties in the hibernate.cfg.xml file, such as thread .
Inheritance, Associations, and Collections are all supported by Hibernate.
Lightweight and open source
Independent of the database
Caching in two layers
Because of its internal cache, the Hibernate framework is a high-performance framework.
It's a step up from JBDC.
Hibernate supports One-to-Many, One-to-One, Many-to-Many-to-Many, and Many-to-One interactions.
Quick performance
Property of the Version
Scalability is simple.
It uses XML files to map java classes to database tables, and any changes to the database are solely done to these XML files.
Hibernate supports lazy loading.
Hibernate get vs load
get() method
load() method
It's used to get information from a database for specific identification.
It can also retrieve data from a database for certain identification.
The Session.get() method will return null if the object with the supplied identifier cannot be located.
The Session.load() method will throw an ObjectNotFoundException if the object for the supplied identifier cannot be found.
This technique eager loads the object because it returns a completely initialized object.
Because it always returns a proxy object, this function is used to load the object slowly.
The database is always accessed when the get() method is used.
The load() method does not make a database query.
It's slower than load() since it returns a fully initialized object, which impacts the application's speed.
It is a little quicker.
It provides you with an actual object.
It creates a proxy object for you.
If you're unsure whether or not an object exists, use the get() function.
Use the load() method if you are certain the item exists.
Why use Hibernate over JDBC
Hibernate takes care of this mapping for you using XML files, so you don't have to write any code.
In the case of Hibernate, the developer does not need to be an expert at generating complex queries because HQL streamlines the process. In contrast, in the case of JDBC, it is the developer's responsibility to write and tune queries. HQL is a more object-oriented language that is similar to Java.
In JDBC, mapping Java objects to database tables must be handled. Because Hibernate enables transparent persistence, no mapping of database table tuples to application objects is required during RDBMS interaction.
In the case of Hibernate, there is no need to construct a connection pool. You can use the command c3p0. When using JDBC, you must create your connection pool.
Caching must be manually maintained while using JDBC. The Hibernate cache is configured to use the application workspace.
Hibernate Merge vs SaveOrUpdate
Merge()
saveOrUpdate()
The merge() method triggers a MergeEvent handled by the DefaultMergeEventListener Hibernate event listener.
Merge() method, Copy the state of the given object onto the persistent object with the same identifier.
The merge operation can only be called within a transaction; an exception will be thrown outside of a transaction.
use same as saveOrUpdate(Object) but to avoid the "NonUniqueObjectException" exception, we should use the merge(object) method.
The main purpose of the merge method is to update a persistent entity instance with new field values from a detached entity instance.
This method appears only in the Hibernate API.
its return void, void saveOrUpdate(Object object) throws HibernateException.
Hibernate saveOrUpdate() method adds the entity object to persistent context and tracks any further changes. It saved any further changes at the time of committing a transaction.
We can use saveOrUpdate(Object) to add/update an object into database. If an identifier exists, it will update the record; else, add a new record.
The saveOrUpdate method triggers a SaveOrUpdateEvent, which the DefaultSaveOrUpdateEventListener Hibernate event listener handles.
saveOrUpdate() can be used without transaction also, but mapped objects not getting saved if session is not flushed.
