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Difference between revisions of "EclipseLink/UserGuide/JPA/Basic JPA Development/Mapping/Basic Mappings/Lazy Basics"

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EclipseLink JPA performs lazy loading when the <tt>fetch</tt> attribute is set to <tt>javax.persistence.FetchType.LAZY</tt>.
 
EclipseLink JPA performs lazy loading when the <tt>fetch</tt> attribute is set to <tt>javax.persistence.FetchType.LAZY</tt>.
 
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By default, EclipseLink JPA ignores the <tt>fetch</tt> attribute and default javax.persistence.<tt>FetchType.EAGER</tt> applies.
 
By default, EclipseLink JPA ignores the <tt>fetch</tt> attribute and default javax.persistence.<tt>FetchType.EAGER</tt> applies.
  

Revision as of 09:57, 3 May 2011

EclipseLink JPA

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Lazy Basics

JPA specifies that lazy loading is a hint to the persistence provider that data should be fetched lazily when it is first accessed, if possible.

If you are developing your application in a Java EE environment, you only have to set fetch to javax.persistence.FetchType.LAZY, and EclipseLink persistence provider will supply all the necessary functionality.

When using a @OneToOne or #@ManyToOne mapping in a Java SE environment, to configure EclipseLink JPA to perform lazy loading when the fetch attribute is set to FetchType.LAZY, configure either dynamic or static weaving.

When using a @OneToOne or @ManyToOne mapping in a Java SE environment that does not permit the use of -javaagent on the JVM command line, to configure EclipseLink JPA to perform lazy loading when annotation attribute fetch is set to javax.persistence.FetchType.LAZY, you can use static weaving.

The EclipseLink JPA Support for Lazy Loading by Mapping Type table, below, lists EclipseLink JPA support for lazy loading by mapping type.

For more information, see the following:


EclipseLink JPA Support for Lazy Loading by Mapping Type

Mapping Java EE 1 Java SE

@ManyToMany

EclipseLink JPA performs lazy loading when the fetch attribute is set to javax.persistence.FetchType.LAZY (default).

EclipseLink JPA performs lazy loading when the fetch attribute is set to javax.persistence.FetchType.LAZY (default).

@OneToMany

EclipseLink JPA performs lazy loading when the fetch attribute is set to javax.persistence.FetchType.LAZY (default).

EclipseLink JPA performs lazy loading when the fetch attribute is set to javax.persistence.FetchType.LAZY (default).

@OneToOne

EclipseLink JPA performs lazy loading when the fetch attribute is set to javax.persistence.FetchType.LAZY.

By default, EclipseLink JPA ignores the fetch attribute and default javax.persistence.FetchType.EAGER applies.

To configure EclipseLink JPA to perform lazy loading when the fetch attribute set to FetchType.LAZY, consider one of the following:

@ManyToOne

EclipseLink JPA performs lazy loading when the fetch attribute is set to javax.persistence.FetchType.LAZY.

By default, EclipseLink JPA ignores the fetch attribute and default javax.persistence.FetchType.EAGER applies.

To configure EclipseLink JPA to perform lazy loading when the fetch attribute set to FetchType.LAZY, configure one of the following:

@Basic

EclipseLink JPA performs lazy loading when the fetch attribute is set to javax.persistence.FetchType.LAZY.

By default, EclipseLink JPA ignores the fetch attribute and default javax.persistence.FetchType.EAGER applies.

To configure EclipseLink JPA to perform lazy loading when the fetch attribute set to FetchType.LAZY, consider one of the following:

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