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Difference between revisions of "EclipseLink/UserGuide/JPA/Basic JPA Development/Mapping/Basic Mappings/Lazy Basics"
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If you are developing your application in a Java EE environment, you only have to set fetch to <tt>javax.persistence.FetchType.LAZY</tt>, and EclipseLink persistence provider will supply all the necessary functionality. | If you are developing your application in a Java EE environment, you only have to set fetch to <tt>javax.persistence.FetchType.LAZY</tt>, and EclipseLink persistence provider will supply all the necessary functionality. | ||
− | When using a @OneToOne or | + | When using a @OneToOne or @ManyToOne mapping in a Java SE environment, to configure EclipseLink JPA to perform lazy loading when the <tt>fetch</tt> attribute is set to <tt>FetchType.LAZY</tt>, 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 <tt>-javaagent</tt> on the JVM command line, to configure EclipseLink JPA to perform lazy loading when annotation attribute <tt>fetch</tt> is set to <tt>javax.persistence.FetchType.LAZY</tt>, you can use static weaving. | When using a @OneToOne or @ManyToOne mapping in a Java SE environment that does not permit the use of <tt>-javaagent</tt> on the JVM command line, to configure EclipseLink JPA to perform lazy loading when annotation attribute <tt>fetch</tt> is set to <tt>javax.persistence.FetchType.LAZY</tt>, you can use static weaving. | ||
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The [[#Table 19-33|EclipseLink JPA Support for Lazy Loading by Mapping Type]] table, below, lists EclipseLink JPA support for lazy loading by mapping type. | The [[#Table 19-33|EclipseLink JPA Support for Lazy Loading by Mapping Type]] table, below, lists EclipseLink JPA support for lazy loading by mapping type. | ||
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For more information, see the following: | For more information, see the following: | ||
* [[#How to Configure Dynamic Weaving for JPA Entities Using the EclipseLink Agent|How to Configure Dynamic Weaving for JPA Entities Using the EclipseLink Agent]] | * [[#How to Configure Dynamic Weaving for JPA Entities Using the EclipseLink Agent|How to Configure Dynamic Weaving for JPA Entities Using the EclipseLink Agent]] | ||
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* [[#How to Disable Weaving Using EclipseLink Persistence Unit Properties|How to Disable Weaving Using EclipseLink Persistence Unit Properties]] | * [[#How to Disable Weaving Using EclipseLink Persistence Unit Properties|How to Disable Weaving Using EclipseLink Persistence Unit Properties]] | ||
* [[#What You May Need to Know About Weaving JPA Entities|What You May Need to Know About Weaving JPA Entities]] | * [[#What You May Need to Know About Weaving JPA Entities|What You May Need to Know About Weaving JPA Entities]] | ||
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<span id="Table 19-33"></span> | <span id="Table 19-33"></span> |
Revision as of 11:14, 3 May 2011
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Key API
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.
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. |
@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. |
@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. |