KB6833: How is a service segmented in MicroStrategy Narrowcast Server

During service execution in Strategy Narrowcast Server 8.x, the Distribution Manager passes the subscription identifier and the service segment size to the Subscription Book Module (SBM). The SBM, then, divides the Subscription Set into segments and the SBM passes the segments and the number of recipients back to the Distribution Manager.
 
The segments are, then, inserted into the segment execution queue.

NOTE: The service segment size by default is 100.
 
To distribute the load as equally as possible among Execution Engines, the Primary Distribution Manager (PDM) creates an instance of the SBM and ask it to segment the Subscription Set in a number of segments, depending on the segment size for that particular service.
 
EXAMPLE:
Consider a service with segment size = 10 that is to be executed to Subscription Set 1, that contains 32 users. The communication between the PDM and the SBM is similar to the following:

• PDM asks SBM to Segment (Subscription Set 1, segment size=10)
• After running a query against the Subscription Book repository (for static subscription sets) or running a Strategy 8.x report (for dynamic subscription sets), the SBM returns a list of segments to the PDM

seg1= (recipients 1 to 10)
seg2= (recipients 11 to 20)
seg3= (recipients 21 to 30)
seg4= (recipients 31 to 32)
It is important to note that the PDM does not know how to interpret the segments returned by the SBM. The PDM only knows that there are four of them and that the SBM will deal with them later, during each segment execution.
In some instances, SBM requires running a report to segment the service (as with dynamic subscription sets). When this is the case, the SBM requests an instance of the Information Source that will run the report, it uses it to run the segmentation report (Segment Information Object), then it returns the segments to the PDM, the same as in the previous example.
 
NOTE:
If the Subscription Set segmentation fails, the service is also failed. This can occur if the SBM cannot connect to the Subscription Book Repository database (e.g., network difficulties, database is down, incorrect ODBC settings, etc.).
 
A common situation, that is not considered an error, is when the SBM returns 0 recipient. In this case the service execution is terminated successfully.
 
For a full explanation of the Strategy Narrowcast Server execution flow please see the Product Manual, 'Narrowcast Server System Administration Guide', Appendix F: 'Service Execution Flow in Narrowcast Server'.
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