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EclipseLink/Examples/JPA/Indexes
< EclipseLink | Examples | JPA
Revision as of 12:24, 24 January 2011 by James.sutherland.oracle.com (Talk | contribs) (New page: Indexes EclipseLink (as of 2.2) provides a way to have a database INDEX generated when EclipseLink is used to generate the database. An [http://en.wik...)
EclipseLink (as of 2.2) provides a way to have a database INDEX generated when EclipseLink is used to generate the database.
An index is used in a database to optimize queries that use that column to provide optimal look-up and avoid table scans.
Different databases have different levels of index support, EclipseLink supports the creation of basic indexes on databases that support them.
EclipseLink supports index creation using its @Index
annotation or <index>
xml element.
The @Index
has a name and a set of columns.
Example Index
The firstName and lastName are indexed.
@Entity @Index(name="EMP_NAME_INDEX", columns={@Column(name="F_NAME"),@Column(name="L_NAME")}) public class Employee{ @Id private long id; @Index @Column(name="F_NAME") private String firstName; @Index @Column(name="L_NAME") private String lastName; ... }
This produces the SQL,
CREATE INDEX </sql>