Blend Unit

Determining which dimension should be defined as the Blend Unit is a key decision which will affect the performance of the BI Blend process and the reporting results.

The Blend Unit acts to define the dimension which is used to break down the data into effective pages for processing, or partitions. Blend Unit’s page are used to process the aggregations defined in the BI Blend settings, such as Account or UD aggregations.

Each Blend Unit member’s aggregations are executed as part of a multi-threading process. The selection of a dimension as the Blend Unit can impact the performance of the application. The larger the number of Blend Unit pages, the more opportunity there is for multi-threading tasks to be initiated.

Examples

Diagram showing Entity hierarchy (Houston with South Houston and Houston Heights) and UD3 hierarchy (CostCenter with Admin and IT, each 100 base members)

  • An entity structure with three members requires all aggregation to happen within only three members.

  • Assigning the larger Dimension as the Blend Unit, such as UD3 (200 members) as the Blend Unit, would allow multi-threading to process more aggregations on smaller datasets.

  • Larger Blend Unit members enhance performance through a more even distribution of records.

  • When a Blend Unit page completes the aggregation process, the engine loops over the rows on the page and summarizes any duplicate rows, but not with duplicates created in another page. 

  • Derivative rules run on each page, for a single row, in an exclusive manner for that page and do not cross pages.

  • Many members in the Blend Unit means smaller pages which leads to better memory management, faster aggregation performance, and more parallel processing.

Performance Settings

BI Blend processing is a CPU and memory intensive process. The number of table records is heavily impacted by the Attribute details in the records and level of aggregations defined for cube dimensions. In each BI Blend configuration setting, the performance can be tailored to the environment with the Performance Controls properties. See Performance Controls Settings.

Blend Unit Partitioning

The concept of partitioning a Blend Unit is a performance solution for large data sets aggregating within a Blend Unit. This permits multi-threading of the aggregations within the Blend Unit. 

Blend Unit partitioning is accomplished by assigning the Data Source's Source ID property to a record field. The members within this field will be used as the key to partition aggregations within the Blend Unit page. The resulting records will be not be summarized across the Source ID/Blend Unit partition. 

IMPORTANT: BI Blend Derivative Rules cannot reference data in other partitions. If calculations are required to cross partitions, then these will need to be performed in the source data set or in the reporting layer.

The Source ID is outlined

BI Blend's assignment of a Blend Unit and aggregation generates pages, which are visible in the Log File. Each Blend Unit Page cannot exceed 2gb. If the 2gb size is exceeded, the aggregation will fail and the following error message will display: Error Array Dimensions Exceeded Supported Range. If a solution is impacted by size constraints, it is to increase the size of the Blend Unit dimension being used or reduce the number of dimensions used in BI Blend.