RE: [birt-dev] Re: [birt-pmc] parallel data retrieval

["Wenfeng Li" <wli@xxxxxxxxxxx>]

Eric,

Following are a couple examples on www.birt-exchange.com

1. Excample of change the query based on report parameter.  Similar
script can be added to change a global JS based on the first data set
and then user that JS global to change the query in the 2nd data set.
http://www.birt-exchange.com/modules/wfdownloads/singlefile.php?cid=2&li
d=176

2.  Subreport example where the query in 2nd data set depends on each
row in the first data set.
http://www.birt-exchange.com/modules/wfdownloads/singlefile.php?cid=2&li
d=77

Wenfeng

-----Original Message-----
From: birt-dev-bounces@xxxxxxxxxxx [mailto:birt-dev-bounces@xxxxxxxxxxx]
On Behalf Of Eric Deshayes
Sent: Friday, November 16, 2007 11:48 PM
To: Birt-dev@xxxxxxxxxxx
Subject: [birt-dev] Re: [birt-pmc] parallel data retrieval


Hi Wenfeng,
thanks for your answer.
I was not aware of such features and I am actually interested in
understanding 
how to achieve that.
ow do you set your query to have the second dataset dependant on the
first 
one? Is that at the report engine or the data engine level?
I am personally using the BIRT data engine in order to generate live
report 
with some realtime update. I am not using the ReportEngine itself but I
have 
spent a lot of time diggin into the BIRT code.
Would there be a place where I could find some design and technical 
documentation (more than the javadoc?
Thanks,
Eric
On Friday 16 November 2007 02:10:45 pm Wenfeng Li wrote:
> Eric
>
> Birt-dev@xxxxxxxxxxx is for this type of design and implementation 
> discussion.
>
> One reason we are not able to do parallel data fetching is that BIRT 
> supports scripting.  Developer can write script such that the 
> visibility of the report item that uses  the 2nd data set depends on 
> the value in the first data set.  Developer can also write script that
changes the
> query in the 2nd dataset based on the value in the first dataset.
All
> this will require BIRT engine to do code analysis before deciding on
an
> execution plan.   It would be an interesting project to optimize the
> execution plan of a report based on static analysis of the report 
> design XML.
>
>
> Wenfeng
>
>
>
>
>
> -----Original Message-----
> From: birt-pmc-bounces@xxxxxxxxxxx 
> [mailto:birt-pmc-bounces@xxxxxxxxxxx]
> On Behalf Of Eric Deshayes
> Sent: Friday, November 16, 2007 12:05 PM
> To: birt-pmc@xxxxxxxxxxx
> Subject: [birt-pmc] parallel data retrieval
>
>
> Hi all,
> I am not sure this is the best mailing list for such a question.. Let 
> me know if there is a better mailing list. At the moment, the data 
> engine makes all the data retrieval sequentially. So, if we are 
> accessing two independant datasources that respond independantly in 
> the same amount of time, we need to wait for both to return some data 
> one after each other. Wouldn't that be a good improvement to do the 
> request in parallel, in two different thread so the time of the data 
> retrieval will be the time of the longest datasource retrieval? I have

> no idea how feasible it is in the current BIRT data engine design. 
> Thanks for your feedbacks/comments. Eric 
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-- 
--
Eric Deshayes
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