Dynamic insert and Dynamic update in Hibernate

Hibernate Dynamic insert and Dynamic update

1.       Dynamic insert: In hibernate by default dynamic insert attribute is false it means when an object is inserted to the database it will include all columns whose values are null i.e. it will generate an insert statement with all unnecessary columns. For example see below code.

        Stock stockTran = new Stock ();

        //stockTran.setPriceOpen(new Float("1.2"));

        //stockTran.setPriceClose(new Float("1.1"));

        //stockTran.setPriceChange(new Float("10.0"));

        stockTran.setVolume(2000000L);

        stockTran.setDate(new Date());

        stockTran.setStock(stock);

        session.save(stockTran);

make show_sql true in hibernate configuration and you will see following insert statement generated by Hibernate SQL.

INSERT 

    INTO

stock

        (DATE, PRICE_CHANGE, PRICE_CLOSE, PRICE_OPEN, STOCK_ID, VOLUME) 

    VALUES

        (?, ?, ?, ?, ?, ?)

Hibernate will generate the unnecessary columns (PRICE_CHANGE, PRICE_CLOSE, PRICE_OPEN) for the insertion.

Now make dynamic insert attribute true and try to insert the same stock object data and you will see that hibernate insert statement excludes all the null property values.

Now hibernate generates the following insert statement.

    INSERT 

    INTO

        stock

        (DATE, STOCK_ID, VOLUME) 

    VALUES

        (?, ?, ?)

Hibernate will generate only the necessary columns (DATE, STOCK_ID, VOLUME) for the insertion.

The main concern is performance issue

In some situations, such as a very large table with hundreds of columns (legacy design), or a table contains extremely large data volume, insert something not necessary definitely will drop down your system performance. So it is highly recommended to use the Dynamic Insert attribute true.

a.       Dynamic insert configuration using Annotation

@Entity

@Table(name = "stock ")

@org.hibernate.annotations.Entity(

              dynamicInsert = true

)

public class Stock implements java.io.Serializable {}

b.      Dynamic insert configuration using XML

<class ... table="stock " dynamic-insert="true">

        <id name="stockId" type="java.lang.Integer">

            <column name="STOCK_ID" />

        </id>

2.       Dynamic Update: By default hibernate set this attribute false means when we updated an object to the database using hibernate it generate the update SQL for all columns i.e. also for the columns those are not modified due to this update statement we face the system performance issue if we are playing with a table which has many columns or more data.

For example see the below code.

Query q = session.createQuery("from Stock where stockId = : stockId");

   q.setParameter("stockId ", 11);

   Stock stock = (Stock)q.list().get(0);

   stock.setVolume(4000000L);

   session.update(stock);

Hibernate will generate the following update statement

    UPDATE

        stock 

    SET

        DATE=?,

        PRICE_CHANGE=?,

        PRICE_CLOSE=?,

        PRICE_OPEN=?,

        STOCK_ID=?,

        VOLUME=? 

    WHERE

        STOCK_ID=?

That is hibernate will update all the unmodified columns.

But when we make dynamic update attribute true which means all the unmodified columns will be excluded from the updated statement.

For the above written update code hibernate will generate the following sql.

UPDATE

stock 

    SET

        VOLUME=? 

    WHERE

        STOCK_ID=?

That is hibernate will updated the modified columns only.

Performance Concern: 

In a large table with many columns (legacy design) or contains large data volumes, update some unmodified columns are absolutely unnecessary and great impact on the system performance. So we should use the dynamic update attribute true.

a.       Dynamic update configuration using Annotation

@Entity

@Table(name = "stock ")

@org.hibernate.annotations.Entity(

         dynamicUpdate = true

)

public class Stock implements java.io.Serializable {}

b.      Dynamic update configuration using XML

<class ... table="stock " dynamic-update="true">

        <id name="stockId" type="java.lang.Integer">

        <column name="STOCK_ID" />

//add generator

        </id>