Jun 2, 2018 - This post shows you how to perform the INSERT and UPDATE batch operations in Java using the Hibernate ORM framework. Hibernate stores. 178931 16:16:16 66 Query SELECT 1 566 Query SET autocommit=0 566 Query select @@session.tx_read_only 566 Query insert into emp (id, name, dep) values ('1', 'clark', 'IT'),('2', 'robin', 'Market'),('3', 'jeff', 'IT'),('4', 'emily', 'HR') 566 Query insert into emp (id, name, dep) values ('5', 'john', 'Sales') How does spring data internally work? Before discussing how to enable this behavior from an EJB 3 application using Hibernate, the example data model above needs further explanation. The primary key of the EJB3.OrderLine table is the OrderId, and the LineNumber. Originally, the entity Order and OrderLine had a MySQL auto increment column as the OrderId, and the primary key of Order, and the first half of the primary key of the OrderLine entity. The SQL syntax for normal inserts is unaffected by this, as Hibernate does not need to know the primary key value ahead of time. In fact, the order in which those SQL statements are sent to the database does not matter. With batch inserts, since we want to send them all over as one set, and eventually as one SQL statement, Hibernate needs to know the primary key ahead of time. This is for the simple reason that Hibernate pushes each 'persist' request from an EJB 3 application into an action queue, and there may be inserts to various tables interleaved in a single transaction. Hibernate has to sort the inserts by primary key in order to batch them at all. An auto increment column value is only known after the insert, so this will fail. Therefore the model has to use a primary key that can be known prior to being inserted into the database. A generated value can be used as the primary key, but the generation strategy used must allow it to be retrieved via JDBC before the inserts are flushed to the database. IDENTITY cannot be used as a primary key generation strategy, but TABLE, SEQUENCE and UUID can be used. It's important to know that when Hibernate performs sorting to get the insert statements batched together it uses the hash code value of the entity so it's imperative that the hash code method is properly defined. The method is annotated with a TransactionTimeout annotation that specifies a longer transaction timeout value, because the default of 300 seconds is too short in this instance. The method takes a single parameter called batchSize which allows tuning of the batch insert size. This is good practice because it allows different batch insert sizes to be tested to optimize the results. After creating the inventory entity, persist is called on the entity manager. The code that follows is significant in demonstrating the batch processing method. After calling persist a check is made to confirm that the number of entities or rows persisted is equal to the batchSize parameter. If so, the entity manager's flush method is called. Since this is a single large transaction, the normal Hibernate behavior is to flush everything on the transaction commit, or when the JDBC batch size has been reached. Download wallpaper bergerak anime android. To flush a specific number of rows, instead of letting Hibernate decide, an explicit call to flush is made. Note that Hibernate will flush at two intervals: at the commit of the transaction and when it gets to the JDBC batch size parameter. So there's no need to explicitly call flush at all, instead set the JDBC batch size parameter and avoid the batch size parameter altogether. In this case the batch size parameter was explicitly set to the maximum once, then different batch sizes less than or equal to the JDBC batch size parameter were tested. This could be simpler, but the alternative would be to change the Hibernate configuration and redeploy the application in between tests. The Hibernate JDBC batch size parameter (hibernate.jdbc.batch_size) is specified in the properties values of persistence.xml for the persistence unit of the application entities. Below is an extract from the configuration file with both these parameters set: org.hibernate.ejb.HibernatePersistence java:/MySqlDS. Note there is no call to the entity manager's flush method. Everything is accomplished through the persistence unit's Hibernate configuration, which is as follows: org.hibernate.ejb.HibernatePersistence java:/MySqlDS. The same two configuration parameters for Hibernate are used, where the inserts are ordered, and the JDBC batch size is set.
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