How to Bulk update in HIbernate - mysql

Question

I need to update multiple rows in my MySQL database using Hibernate. I have done this using JDBC where we have the support of batched Query. I want something like this in hibernate.
Does hibernate support batched Query?
Batched Query Example in jdbc:
// Create statement object
Statement stmt = conn.createStatement();
String SQL = "INSERT INTO Employees (id, first, last, age) " +
"VALUES(200,'Zia', 'Ali', 30)";
// Add above SQL statement in the batch.
stmt.addBatch(SQL);
// Create one more SQL statement
String SQL = "INSERT INTO Employees (id, first, last, age) " +
"VALUES(201,'Raj', 'Kumar', 35)";
// Add above SQL statement in the batch.
stmt.addBatch(SQL);
int[] count = stmt.executeBatch();
Now when we issue stmt.executeBatch call Both Sql Query will be executed in a single jdbc round trip.

Answer 1

You may check the Hibernate documentation. Hibernate has some configuration properties that control (or disable) the use of JDBC batching.
If you issue the same INSERT multiple times and your entity does not use an identity generator, Hibernate will use JDBC batching transparently.
The configuration must enable the use of JDBC batching. Batching is disabled by default.
Configuring the Hibernate
The hibernate.jdbc.batch_size property defines the number of statements that Hibernate will batch before asking the driver to execute the batch. Zero or a negative number will disable the batching.
You can define a global configuration, e.g. in the persistence.xml, or define a session-specific configuration. To configure the session, you can use code like the following
entityManager
.unwrap( Session.class )
.setJdbcBatchSize( 10 );
Using the JDBC batching
As mentioned before, Hibernate call the JDBC batching transparently. If you wanna control the batching, you can use the flush() and clear() methods in the session.
The following is an example from the Documentation. It calls flush() and clear() when the number of insertions reach a batchSize value. It works efficiently if batchSize is lesser or equal than the configured hibernate.jdbc.batch_size.
EntityManager entityManager = null;
EntityTransaction txn = null;
try {
entityManager = entityManagerFactory().createEntityManager();
txn = entityManager.getTransaction();
txn.begin();
// define a batch size lesser or equal than the JDBC batching size
int batchSize = 25;
for ( int i = 0; i < entityCount; ++i ) {
Person Person = new Person( String.format( "Person %d", i ) );
entityManager.persist( Person );
if ( i > 0 && i % batchSize == 0 ) {
//flush a batch of inserts and release memory
entityManager.flush();
entityManager.clear();
}
}
txn.commit();
} catch (RuntimeException e) {
if ( txn != null && txn.isActive()) txn.rollback();
throw e;
} finally {
if (entityManager != null) {
entityManager.close();
}
}