Re: [eclipselink-users] batch reading with separate fetch size setting

[James Sutherland <jamesssss@xxxxxxxxx>]

Use prepareCall(Session, Record), it is a public API.

i.e.
query.prepareCall(session, null);

The row is normally not important.



Thomas Paradies-2 wrote:
> 
> James,
> 
> your idea to prepare() the query to get the nested batch query via
> getBatchReadMappingQueries() is nice but prepare() in ReadAllQuery is not
> visible due to protected access ... or am I overlooking something?
> 
> 
> 
> ----- Original Message ----
> From: James Sutherland <jamesssss@xxxxxxxxx>
> To: eclipselink-users@xxxxxxxxxxx
> Sent: Monday, October 6, 2008 4:58:57 PM
> Subject: Re: [eclipselink-users] batch reading with separate fetch size
> setting
> 
> 
> There is no query hint to do this, feel free to log an enhancement request
> for this.
> 
> You can configure this using the ReadAllQuery code API.
> 
>> 
>> 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
>>> 
>> 
> 
> 
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-----
---
http://wiki.eclipse.org/User:James.sutherland.oracle.com James Sutherland 
http://www.eclipse.org/eclipselink/
 EclipseLink ,  http://www.oracle.com/technology/products/ias/toplink/
TopLink 
Wiki:  http://wiki.eclipse.org/EclipseLink EclipseLink , 
http://wiki.oracle.com/page/TopLink TopLink 
Forums:  http://forums.oracle.com/forums/forum.jspa?forumID=48 TopLink , 
http://www.nabble.com/EclipseLink-f26430.html EclipseLink 
Book:  http://en.wikibooks.org/wiki/Java_Persistence Java Persistence 
-- 
View this message in context: http://www.nabble.com/batch-reading-with-separate-fetch-size-setting-tp19767497p19899418.html
Sent from the EclipseLink - Users mailing list archive at Nabble.com.