Re: [eclipselink-users] Lazying-loading and Collection.size()

[cowwoc <cowwoc@xxxxxxxxxxxxxxxx>]

In other words, it will retrieve the entire resultset and dump it into
memory? Is there a way to perform the following operations efficiently?

1) get the size of the collection
2) retrieve an element at index X

all of this without retrieving the entire collection from the database and
(ideally) without issuing queries explicitly.

Gili


James Sutherland wrote:
> 
> size() will instantiate lazy collections in EclipseLink and any other JPA
> implementation that I know of.  I'm not sure the JPA spec says anything
> about it.
> 
> 
> 
> cowwoc wrote:
>> 
>> Hi,
>> 
>> What does the JPA standard (and alternatively EclipseLink) say about Lazy
>> Loading and Collection/Set/List.size()? If the collection hasn't been
>> initialized yet, does size() simply invoke a count(*) query or does it
>> retrieve the entire collection including its elements?
>> 
>> I'm thinking of the following use-case:
>> 
>> 1) int size = myList.size();
>> 2) Object randomElement = myList.get((int) (Math.random() * size));
>> 
>> What is guaranteed to happen under the hood according to JPA and
>> according to EclipseLink? Ideally I want to pass a Collection around my
>> API, instead of forcing it to be Query-aware and issue SQL statements
>> explicitly.
>> 
>> Thank you,
>> Gili
>> 
> 
> 

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