COGNOiSe.com - The IBM Cognos Community

IBM Cognos 8 Platform => COGNOS 8 => Report Studio => Topic started by: dsds on 27 Jul 2012 05:45:52 PM

Title: Master Detail performance
Post by: dsds on 27 Jul 2012 05:45:52 PM
Are Master detail reports known to create performance issues?
Title: Re: Master Detail performance
Post by: blom0344 on 30 Jul 2012 06:51:06 AM
Yes, in general they are slower then 'flat' reports.  We had really major issues with M/D reports with many datacontainers as detail coupled to a master.  THere is a best practice article somewhere on improving performance by using query references I believe..
Title: Re: Master Detail performance
Post by: CognosPaul on 30 Jul 2012 08:00:13 AM
The Cognos 10 DQM is also smart enough to (occasionally) throw one query for most master detail scenarios.
Title: Re: Master Detail performance
Post by: barrysaab on 31 Jul 2012 12:34:16 AM
Thanks,Paul,but isn't it the intrinsic requirement for master detail report is whe two data container like list and chart use different queries to fetch different related information.How it is possible to allocate one query for these two.Could you please explain.
Title: Re: Master Detail performance
Post by: blom0344 on 01 Aug 2012 03:01:44 AM
Different datasets require multiple queries. You will not get around that one. However, it would be wrong to assume that each and every master-detail report would perform badly. Build a test report and gradually feed more data to the report..
Title: Re: Master Detail performance
Post by: CognosPaul on 02 Aug 2012 01:58:31 AM
It is true that generally master detail will throw separate queries for each query. However consider the following scenario:

chart showing years (x), product line (y), revenue (measure), sectioned by country.  The DQM will throw only one query for that and separate the data locally for the charts.