Difference Between Group By And Calculated Item

                                                        Group by and Calculated Items

It is important to understand the differences between two types of selection steps: groups and calculated items.

Performance considerations - 

• Calculated items are computed on presentation server. They are executed on the (normally small) result set retrieved from BI Server. Usually they do not have any impact on performance.

• Groups are computed on the database. They generate additional logical and physical queries. They have a significant impact on resources required on the database, and therefore on global Performance.

Functionality perspective - 

• Calculated items formula are exactly applied on result set as they are. Aggregation rules used to compute the metrics on BI Server are not considered.
• Groups generate a query with a filter based on members selected. Aggregation rules are applied on BI Server as usual.

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