How to use existing Oracle sequence to generate id in hibernate?

user_193702 0
Viewed 101755

I have legacy Oracle db with a sequence named PRODUCT_ID_SEQ.

Here is the mapping of Product class for which I need generate correct ids:

public class Product {
   @GeneratedValue(strategy = GenerationType.SEQUENCE, 
                       generator = "retailerRaw_seq")
   @SequenceGenerator(name = "retailerRaw_seq", 
                      sequenceName = "PRODUCT_ID_SEQ")
   private Long id;

   ...
}

But looks like ids are generated with an interval of 50, like 1000, 1050, 1100 etc. This corresponds to the default value of allocationSize property = 50. So that means that Hibernate doesn't actually use the sequence which is already defined in the db.

How do I make Hibernate use the sequence?

sequence oracle hibernate
10 Answers

I'm not used to use annotations, this is what I have in my *.hbm.xml:

<id name="id" type="java.lang.Integer">
    <column name="ID_PRODUCT" />
    <generator class="sequence-identity" >
        <param name="sequence">PRODUCT_ID_SEQ</param>
    </generator>
</id>

You can easily map this to annotations. The generator sequence-identity uses auto increment with sequences.

user_1519180


By default Hibernate uses sequence HiLo generator which ,unless you have special needs, it is good (performance wise). You can read more of that in my blog here

Eyal

user_1255550

First : you should create in your database the sequence like: 

CREATE SEQUENCE  "PRODUCT_ID_SEQ"  MINVALUE 0 MAXVALUE 1000000000 INCREMENT BY 1 START WITH 1 CACHE 500 NOORDER  NOCYCLE ;

and in your file Product.hbm.xml configuration make : 

 <class name="ProductPersistant" table="Product">

    <id  name="id"  type="java.lang.Long" column="productID" >
          <generator class="sequence"> 
               <param name="sequence">PRODUCT_ID_SEQ</param>   
          </generator>
    </id>
user_84955330
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