Hi Marina,
Currently only OneToOne, OneToMany, ManyToOne, and ManyToMany mappings
are treated specially when they are annotated as LAZY. Other mappings
are always loaded eagerly. I believe there are plans to add support for
LAZY Blobs and other mapipngs in the future.
-Tom
Marina Vatkina wrote:
>Tom,
>
>What happens if any other field or property (e.g. LOB) is marked as LAZY?
>Are they treated the same way as the ToOne relationship?
>
>thanks,
>-marina
>
>Tom Ware wrote:
>
>
>>Hi,
>>
>> Here's some additional information.
>>
>> TopLink Essentials uses some fundamental TopLink features to implement
>>indirection.
>>1. For OneToMany and ManyToOne, TopLink weaves your classes to include
>>implementations of TopLink's ValueHolderInterface
>>2. For OneToMany and ManyToMany, TopLink uses a feature called
>>transparent indirection
>>
>> Here is a pointer to the documentation for those features for the
>>non-JPA TopLink product.
>>
>>http://www.oracle.com/technology/products/ias/toplink/doc/10131/main/_html/mapun002.htm#CHDJAHDC
>>
>>
>>-Tom
>>
>>Peter Krogh wrote:
>>
>>
>>
>>>ToOnes (One to ones and Many to Ones) and ToManys (one to manys and
>>>many to manys) relationships work differently with respect to lazy
>>>loading.
>>>
>>>
>>>
>>>
>>>>- in a One to Many mapping would company.getLocations() load the many
>>>>side (Location) or is it expected to get loaded only on doing something
>>>>with it eg: company.getLocations().iterator()?
>>>>
>>>>
>>>>
>>>in this example 'locations' would get loaded when you call something
>>>on the collection. This is because TopLink Essentials has its own
>>>Collection implementation that lazily loads relationships. In order
>>>for the relationship to be loaded, an action must be performed on
>>>TopLink Essentials Collection class.
>>>
>>>
>>>
>>>
>>>
>>>>- Same question for Many To One, when will the relationship be loaded,
>>>>on execution of employee.getDepartment() or
>>>>employee.getDepartment().getName()?
>>>>
>>>>
>>>>
>>>Department would get loaded when you call getDepartment(). This is
>>>because TopLink Essentials weaves in a proxy class (ValueHolder) for
>>>one to one (and many to one) relationships. The method access is
>>>woven to trigger the proxy.
>>>
>>>Peter
>>>
>>>-----Original Message-----
>>>From: Varun.Rupela_at_Sun.COM [mailto:Varun.Rupela_at_Sun.COM]On Behalf Of
>>>Varun Rupela
>>>Sent: Monday, December 11, 2006 11:47 PM
>>>To: persistence_at_glassfish.dev.java.net
>>>Subject: Need Doc help on Lazy Loading
>>>
>>>
>>>Hi:
>>>
>>>Kindly help with the below question. Pointers to docs that describe
>>>toplink's lazy loading feature will be greatly appreciated.
>>>
>>>When is a relationship loaded if the fetch attribute is set to LAZY- on
>>>use of the getter or when doing an operation on the relationship entity
>>>after using the getter. Example:
>>>- in a One to Many mapping would company.getLocations() load the many
>>>side (Location) or is it expected to get loaded only on doing something
>>>with it eg: company.getLocations().iterator()?
>>>- Same question for Many To One, when will the relationship be loaded,
>>>on execution of employee.getDepartment() or
>>>employee.getDepartment().getName()?
>>>
>>>I found
>>>http://www.oracle.com/technology/products/ias/toplink/jpa/resources/toplink-jpa-extensions.html#LazyLoading
>>>
>>>but it does not help with the above question.
>>>
>>>thanks.
>>>
>>>varun.
>>>
>>>
>>>
>>>