Aggregates

Definition

An aggregate is a materialized, aggregated view of the data in an InfoCube. In an aggregate, the dataset of an InfoCube is saved redundantly and persistently in a consolidated form into the database.

Use

Aggregates make it possible to access InfoCube data quickly in Reporting. Aggregates serve, in a similar way to database indexes, to improve performance.

We recommend that you create aggregates, especially in the following cases:

·        The execution and navigation of query data leads to delays with a group of queries.

·        You want to speed up the execution and navigation of a specific query.

·        You often use attributes in queries.

·        You want to speed up reporting with characteristic hierarchies by aggregating specific hierarchy levels.

Aggregate Screen Information

An aggregate is made up of characteristics and navigation attributes belonging to an InfoCube. You can group the data according to different Aggregation Levels. In doing so, you can also store values for hierarchy levels belonging to an external hierarchy. Both time-dependent attributes and time-dependent hierarchies can be used in aggregates. Characteristics that are not used in the aggregate are brought together.

If you have created aggregates for an InfoCube and entered data for them, the OLAP processor automatically accesses these aggregates. When navigating, the different results are consistent. The aggregate is transparent for the end user.

New data is loaded at a defined time using logical data packages (requests) in an aggregate. After this transaction, the new data is available for rolling up in reporting. 

Prerequisites

The InfoCube for which you want to create an aggregate has been saved and is active.

 Editing Aggregates

Procedure

How to create or change an aggregate for an InfoCube is described below.

...

       1.      You are in the Modeling function area of the Administrator Workbench.In the navigation window, choose InfoProvider.

       2.      In the InfoProvider tree, navigate to the InfoCube whose queries you want to optimize.

       3.      In the context menu for the InfoCube, choose Maintain Aggregate.This will bring you to the Maintain Aggregates screen.

If an aggregate was already created for the selected InfoCube, you can also go to the maintenance screen by double-clicking on .

If you create the first aggregate for an InfoCube, you will first go to the Proposals for Aggregates dialog box. You can define whether the system should propose aggregates or whether you want to create them manually.

For more information, see Creating the First Aggregate for an InfoCube.

       4.      The left side of the screen shows the dimensions, characteristics and navigation attributes of the selected InfoCube in a tree structure as Selection Options for Aggregates.

Select one or more objects to be copied to the aggregate.

 

Define the granularity you need for the data in the aggregate. Add all the characteristics derived from these characteristics.

For example if you define an aggregate for the month, you should also include the quarter and year in the aggregate.

This enhancement does not increase the data set, but permits

·         a year aggregate to be built from this aggregate,

·         those who need the annual values can also use queries of this aggregate.

 

You can only include a characteristic and one of its attributes in an aggregate in expert mode (Extras  ®  Switch expert mode on/off). Such an aggregate has the same granularity and size as an aggregate that was only built with the characteristic, but is affected by the hierarchy/attribute change run. Compared with the aggregate for the characteristic in which the attribute information is defined by a join with the master data table, the aggregate for the characteristic and the attribute only saves the database join.

We therefore recommend that you either build an aggregate using with the characteristic or you build a much smaller aggregate using the attribute.

       5.      You have different options for creating an aggregate:

·         Transfer the selected object(s) to the Aggregates column on the right side of the screen using Drag&Drop.

·         Select  Create New Aggregate.

The Enter Description for Aggregate dialog box appears.

       6.      Enter:

Short Description

Long Description

 

To change the text at a later time, select Change Description Text from the context menu of the aggregate.

       7.      Choose  Continue. You get to the Maintain Aggregates screen.

The system displays the aggregate at the upper right of the screen. The log is displayed in the lower part of the screen. 

For more information see Displaying an Aggregate and its Components.

       8.      If an aggregate contains a time-dependent component, you must assign a key date to the aggregate.

When you fill the aggregate, the key date behaves like the key date of a query: The time-dependent attributes and hierarchies are evaluated on this key date. For this reason aggregates with a time-dependent component can only be used in a query if the key date of the query is the same as the key date of the aggregate.

In the Select Variable or Fixed Date dialog box select the following as key date:

·         a variable that is also used in queries for the key date and can be automatically calculated in the SAP Exit or Customer Exit processing types (see Using Variables),

0CWD Current workday

0DAT Current calendar day

0P_KEYDT Key date of due date

0P_KEYD2 Key date of posting (from key date of due date)

0P_KEYD3 Key date of clearing (from key date of due date)

0P_KEYD4 Key date of posting (posting date)

0P_KEYD5 Key date of clearing (from key date of posting)

Aggregates with a variable key date must be updated regularly. This process must be included in a Process Chain (Further BW processes -> Adjust Time-Dependent Aggregates).

·         A certain calendar day

To enter a calendar day, select object CALENDAR in the Select Variable or Fixed Date dialog box (<Calendar>). Choose  Transfer selection. This takes you to the Calendar dialog box. You can copy this date to the aggregate definition by double-clicking.

The system displays the technical name of the variable you chose or of the fixed calendar date in the aggregate tree under  Properties for node  Variables for Key Date.

Once the aggregate has been activated and filled, the system copies the key date computed from the variable when the aggregate should be filled into the line  Key Date.

       9.      You can change the structure of the aggregate by adding further components or deleting existing ones. You can also change the key date.

Inserting components into the aggregate

i.         Select one or more objects in Selection Options for Aggregates.

ii.       Transfer them to the aggregate to be changed at the right of the screen with Drag&Drop.

iii.      As needed, change the Aggregation Level with the associated entry in the context menu:

All Characteristic Values

Hierarchy Level

Fixed Value

 

Aggregates containing fewer than 14 components are stored on the database in optimized form (see Efficiently Loading Data into Aggregates).

Note that the characteristics that are defined in the InfoCube are also included in the aggregate and thus increase the number of components even though they are not visible on the surface.

Deleting components from the aggregate

i.         In the aggregate tree navigate to the characteristic(s) or navigation attributes you want to delete.

ii.       Select these components.

iii.      To delete the components from the aggregate you can:

-         Choose Remove Components in the context menu.

-         Copy the components to the left part of the screen with Drag&Drop.

To delete a dimension from an aggregate, you have to delete all the characteristics and navigation attributes of this dimension.

Changing the key date

i.         In the aggregate tree under  Properties, select node  Variable for Key Date and choose Change from the context menu. You get to dialog box Select Variable or Fixed Date.

ii.       Select and transfer the required variable or calendar date.

 

The key date computed from a changed variable is only copied to line  Key Date when the Adjust Time-Dependent Aggregates process has been executed.

   10.      To check the aggregate definition for inconsistencies choose  Check Definition.

   11.      Save the new or changed aggregate.

Result

You can activate the new or changed aggregate and fill it with data. It is then available for reporting.