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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 @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 one-to-one or many-to-one 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 one-to-one or many-to-one 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.
  
 
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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| id="r2c1-t52" headers="r1c1-t52" align="left" |
 
| id="r2c1-t52" headers="r1c1-t52" align="left" |
@ManyToMany
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Many-to_many
 
| headers="r2c1-t52 r1c2-t52" align="left" |
 
| headers="r2c1-t52 r1c2-t52" align="left" |
 
EclipseLink JPA performs lazy loading when the <tt>fetch</tt> attribute is set to <tt>javax.persistence.FetchType.LAZY</tt> (default).
 
EclipseLink JPA performs lazy loading when the <tt>fetch</tt> attribute is set to <tt>javax.persistence.FetchType.LAZY</tt> (default).
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|- align="left" valign="top"
 
|- align="left" valign="top"
 
| id="r3c1-t52" headers="r1c1-t52" align="left" |
 
| id="r3c1-t52" headers="r1c1-t52" align="left" |
@OneToMany
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One-to-many
 
| headers="r3c1-t52 r1c2-t52" align="left" |
 
| headers="r3c1-t52 r1c2-t52" align="left" |
 
EclipseLink JPA performs lazy loading when the <tt>fetch</tt> attribute is set to <tt>javax.persistence.FetchType.LAZY</tt> (default).
 
EclipseLink JPA performs lazy loading when the <tt>fetch</tt> attribute is set to <tt>javax.persistence.FetchType.LAZY</tt> (default).
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|- align="left" valign="top"
 
|- align="left" valign="top"
 
| id="r4c1-t52" headers="r1c1-t52" align="left" |
 
| id="r4c1-t52" headers="r1c1-t52" align="left" |
@OneToOne
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One-to-one
 
| headers="r4c1-t52 r1c2-t52" align="left" |
 
| headers="r4c1-t52 r1c2-t52" align="left" |
 
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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|- align="left" valign="top"
 
| id="r5c1-t52" headers="r1c1-t52" align="left" |
 
| id="r5c1-t52" headers="r1c1-t52" align="left" |
@ManyToOne
+
Many-to-one
 
| headers="r5c1-t52 r1c2-t52" align="left" |
 
| headers="r5c1-t52 r1c2-t52" align="left" |
 
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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|- align="left" valign="top"
 
|- align="left" valign="top"
 
| id="r6c1-t52" headers="r1c1-t52" align="left" |
 
| id="r6c1-t52" headers="r1c1-t52" align="left" |
@Basic
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Basic
 
| headers="r6c1-t52 r1c2-t52" align="left" |
 
| headers="r6c1-t52 r1c2-t52" align="left" |
 
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>.

Revision as of 09:40, 4 May 2011

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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 one-to-one or many-to-one 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 one-to-one or many-to-one 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

Many-to_many

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).

One-to-many

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).

One-to-one

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.

Many-to-one

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.

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