Datamart and Refresh on demand

[SamAsher]

Can I create complex queries to develop reports even though I am interested in not having a data mart (at least in the beginning), but access the database directly?, On the other hand, If the client will insist in having a data mart, can they still get the concurrent data in their report that reflects the latest changes in the database?

Thanks

 

[blom0344]

First question:

Yes and no. You can still create complex queries, but you may run into performance issues with an OLTP source (to many joins, outer joins , wrong indexation , missing consolidation levels etc)

Second question:

This is (near) real-time datawarehousing. This is more an ETL issue than a reporting one. If your client insists on the latest data available, then the ETL processing should be designed as such. Since datamarts are usually build for strategic purposes (reporting on a fixed monthly,weekly,daily or hourly basis) then running reports on the OLTP system for individual transactions may be a good enough alternative..

Ties Blom

 

[SamAsher]

Is there a middle layer to store the metadata,if yes,is that layer can retrieve up to the minute data from the database?
Right now we run complex queires through Access, and users do ask for up to the minute data as well as static reports that we run once-twice a week. Now, the compnay has purchase Cognos and I am just confused with its ability and capability to develop and replcate reports I have done in Access


Thanks

 

[almeids]

Metadata is information about the data, it doesn't "do" anything and is, in relative terms, static. Framework Manager is the application used to develop and maintain metadata in the Cognos environment and to package that metadata for its reporting applications.
When a Cognos report runs it reads from your database, period. Whether that database is operational, an ODS, a datamart, or your data warehouse is entirely dependent on the reporting requirements and design of your environment and therefore so is the "currency" of what the Cognos report reads.
As in any reporting environment you can run reports interactively or you can pregenerate and save or distribute them in batch.
If your users truly require up-to-the-minute data, then they will need to be running reports interactively against an up-to-the-minute database.