James,
There is no query hint to do this, feel free to log an enhancement request
for this.
done
You can configure this using the ReadAllQuery code API.
I'll give it a try, thank you
Kate Lain wrote:
>
> James,
>
> I have three related entities say A, B, C with an OneToMany mapping both
> between A - B and A - C . There is a need to read all the objects in a
> single query. Therefore i've defined a named query in A as
follows:
>
> @NamedQuery(
> name = "A.findAll",
> query = "SELECT a FROM A a ,
> hints = {
> @QueryHint(name = QueryHints.BATCH, value =
"a.bs"),
> @QueryHint(name = QueryHints.BATCH, value =
"a.cs"),
> @QueryHint(name = QueryHints.JDBC_FETCH_SIZE, value =
"500")
> }
> )
>
> As result I got about 500 objects for A, 5000 objects for B and 50000
> objects for C from the three queries (the one named and the two batch
> queries). Regarding the tuning of the jdbc fetch size I can only define a
> single value as query hint as far as I can gather. I take it that it will
> only taking effect for the A-query wouldn't it? How may I effect then
the
> fetch
size for the batch queries. Or, I'm totally wrong here?
>
> --- On Thu, 10/2/08, James Sutherland <jamesssss@xxxxxxxxx> wrote:
> From: James Sutherland <jamesssss@xxxxxxxxx>
> Subject: Re: [eclipselink-users] batch reading with separate fetch size
> setting
> To: eclipselink-users@xxxxxxxxxxx
> Date: Thursday, October 2, 2008, 6:57 AM
>
> I'm not exactly sure I understand what you mean perhaps give an
example.
>
> Assuming you want to set the fetch size of the nested batch queries, there
> is no easy way to do this. However you could prepare() your query, then
> access the getBatchReadMappingQueries() that are generated to customize
> any
> of the nested batch queries.
>
>
>
> Kate Lain wrote:
>>
>> Hi,
>>
>>
>>
>> for performance reasons I've optimized my
queries using batch
reading
>> and fetch size tuning - but is there a way to set the fetch size
separate
>> per
>> batch query?
>>
>> Thomas
>>
>
-----
---
http://wiki.eclipse.org/User:James.sutherland.oracle.com James Sutherland
http://www.eclipse.org/eclipselink/
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