Should you always copy over the data before reporting agaisnt it?

[TheDrunkenMaster]

Are there times when it is better to report directly against the database? I'm think in cases when you need "real-time" and "on-demand" reporting.

I would appreciate comments on advantages and disadvantages for reporting directly against the database versus copying it over first before reporting against it.

 

[TheDrunkenMaster]

Come on guys, I want to hear you opinion on this subject. Or does anyone know a good article where this has been discussed?

Thanks

 

[griffindm]

DM,

I know of no such article. That doesn't mean it does not exist.

The issues include:

1) Whether of not the users require real time information. This is of particular importance to shipping and receiving, travel reservations, hospital systems, etc.

2) The impact of reporting against the users of the transaction system application. Is there an appreciable increase in system delays due to the database server impact of the reporting queries?

3) The degree of normalization of the transactional data. Some systems are so completely normalized that reporting directly involves many outer-joins and a huge number of tables involved in what would normally be simple queries. In this case, the complexity of the data, and not the impact of the reporting users, steer you toward a data mart solution on a separate database server.

This is not an exhaustive list. If anyone else has additional thoughts please add them.

Regards,

Dave Griffin


The Decision Support Group
Reporting Consulting with Cognos BI Tools
Magic with Data
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