Master Detail performance

[dsds]

Are Master detail reports known to create performance issues?

[blom0344]

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..

[CognosPaul]

The Cognos 10 DQM is also smart enough to (occasionally) throw one query for most master detail scenarios.

[barrysaab]

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.

[blom0344]

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..

[CognosPaul]

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.