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The term Convex Hull is used when the Analytical Engine simplifies the read request which has to be processed by the database(or a virtual provider).  This in general means that a superset of the required data set is returned by the database which then has to be filtered by the Alalytical(OLAP) Engine. This might be necessary in case an SQL statement is extremely complex due to many local query restrictions or when local restrictions are not supported by the interface.

Simple Examples
  • BWonHana
  • BW on AnyDB
    • When SQL is used, the feature convex hull can help to improve the query runtime by avoiding extremely complex(big) SQL statements. See Example III.
SAP Notes
  • 2306646 Customer-specific convex hull for HDB/TREX queries (SAP_BW 7.50)
  • 2145007 Customer-specific convex hull for HDB/TREX queries (SAP_BW 7.30, 7.31, 7.40)
  • 2141172 Limit values for convex hull can be configured database-specifically
  • 2636951 Long database runtimes for queries with structures and pushdown to HANA
  • 2633035 BW with Near-Line Storage and HANA Smart Data Access: Enhancements for Pruning
  • 1814452 Large SID restriction on virtual BW InfoCube
  • NCUM
    • 2410052 BIA/HDB performance problems for non-cumulative queries with many (time) selections → RSADMIN parameter NCUM_CONV_HULL (BW75)
    • 2723998 NCUM: Memory problem during execution of a non-cumulative key figure → new RSADMIN parameter NCUM_CONV_HULL_THRES (BW/4Hana)

Virtual Cube based on Function: Query contains a characteristic with a large number of restrictions

Relevant ABAP Function

RSDRC_SELDR_CONVEX_HULL

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