Aggregation and Grouping are easily confused in the Omniscope Table View - indeed Grouping was known as Aggregation in Omniscope prior to version 2.4! The two are, however, quite different in nature - both purpose and result - and the Aggregation effect can be applied in most views, so is an important concept to understand.

Aggregation allows the Omniscope to work on a reduced data set - so the chosen view (including a Table View) is displaying a different set of data - whereas Grouping is a means of hiding or revealing some of the rows in the data set. It is quite possible to use both techniques together to hide/reveal (Grouping) summarised data rows (Aggregation). The essential difference can be though of as this:

* Aggregation is a data-level summarisation technique which causes data to be summarised before it is presented to the user in one of many views
* Grouping is presentation-level Table View (only) summarisation technique which allows rows to be "rolled up" to a summary level and then expanded by the user to get back to the underlying detail in the Table

When data is aggregated, Omniscope will combine rows based on the options selected - typically this is used to create a summary level of data which can then be manipulated as if it were the base data set in Omniscope. The user selects one or more fields to aggregate by, and Omniscope generates a summarised data set where the values of the selected fields are retained, but all non-selected fields are either ignored (shown as an aggregation value of none) or summarised in some manner (e.g. sum, mean, maximum etc.).The resultant summary data set can be manipulated in Omniscope exactly as if it were the base data held in the Omniscope IOK model. For more information on Aggregation search the FAQ for additional examples.

Grouping allows the user to "roll up" rows within a Table View and then "drill down" into detail within the rows. Grouping is a presentation-level technique and, as such, alters the way in which Table View data is displayed. Once Grouping is active, on one or more fields, Omniscope places an expansion arrow next to each summarised row to allow the user to expand the rolled up row and see the individual data rows beneath (subject to the Grouping > Settings > Expandable tree options being ticked). Grouped data cannot be sorted (the underlying rows are sorted, but not the grouped totals) which can cause confusion - if you need to sort columns of summarised data then use Aggregation.