CODEWITHSUNDEEP
hibernateormjpajpa-2.0
user339108
user339108

Reputation: 13131

Is there an annotation to define a multi column index in jpa2

Hibernate provides a mechanism to define multi column indexes via the Table. Is there a way to specify this is an ORM agnostic fashion via JPA or JPA2 (e.g. using the javax.persistence.* APIs)

Upvotes: 7

Views: 11714

Answers (4)

Nayan
Nayan

Reputation: 1605

It's possible to declare multi-column index in JPA 2.1 Here is a sample Entity class that demonstrates multi-column indexing.

@Entity
@Table(uniqueConstraints=@UniqueConstraint(columnNames={"product_id","store_id"}))
class MyEntity {
    @Column(name="product_id")
    private String productId;

    @Column(name="store_id")
    private Long storeId;
}

Please note that columnNames must be the name of the columns in DB, not the attribute name.

Upvotes: 4

khituras
khituras

Reputation: 1091

Just came about the very same issue using Hibernate 4.3.8 with JPA 2.1 integration. It seems, mjaggard's answer is correct. However, the given example of usage looks like this:

@Index(name="EMP_NAME_INDEX", columnList={"F_NAME", "L_NAME"})

I don't know if this ever worked. I do know that in my case with JPA 2.1 the value of columnList is not an array but a String. So for me, the desired two-column index can be defined in the following way:

@Index(name="EMP_NAME_INDEX", columnList="F_NAME,L_NAME")

That is, just use a comma to separate the column names in a single string. This worked for me using a Postgres DBMS. I checked back and the index was successfully created over both columns.

Upvotes: 10

mjaggard
mjaggard

Reputation: 2485

Yes, it is possible using JPA 2.1 as seen in the specification here:

http://download.oracle.com/otndocs/jcp/persistence-2_1-pfd-spec/index.html

on page 445 it states that

The Index annotation is used in schema generation

columnList (Required) The names of the columns to be included in the index.

An example of usage can be seen here:

http://java-persistence-performance.blogspot.co.uk/2013/03/but-what-if-im-not-querying-by-id.html

Upvotes: 2

Pascal Thivent
Pascal Thivent

Reputation: 570635

No, as hinted in my answer to your previous question, there is no standardized way, you have to use provider extensions for that (when they exist).

Upvotes: 2

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