Optimization With Null-suppression for CALLTYPE=RL

In the ADABAS Interface, optimization refers to using an index to retrieve the answer set. To ensure data integrity and complete answer sets, the ADABAS Interface will perform optimization when:

All non-referenced component fields of a superdescriptor are not null-suppressed (NU=NO in the Access File).

All component fields of a superdescriptor that contain null-suppressed fields (NU=YES in the Access File) are used in the selection criteria.

If a field is null-suppressed in ADABAS (NU=YES in the Access File), any superdescriptor that uses this field has no entry on the inverted list when this field is blank (alphanumeric) or zero (numeric).

GROUP=SUPERG  ,ALIAS=S1 ,USAGE=A9 ,ACTUAL=A9 ,INDEX=I ,$
   FIELD=FLD1 ,ALIAS=AA ,USAGE=A3 ,ACTUAL=A3 ,$
   FIELD=FLD2 ,ALIAS=AB ,USAGE=A3 ,ACTUAL=A3 ,$
   FIELD=FLD3 ,ALIAS=AC ,USAGE=A3 ,ACTUAL=A3 ,$

Figure 6-1. Master File With a Three-field Superdescriptor

FIELD= SUPERG    ,TYPE=SPR,$
    FIELD= FLD1    ,TYPE=   ,NU=YES ,$
    FIELD= FLD2    ,TYPE=   ,NU=NO  ,$
    FIELD= FLD3    ,TYPE=   ,NU=YES ,$

Figure 6-2. Access File With a Three-field Superdescriptor

In order to optimize a selection test against a superdescriptor with null-suppression, you must explicitly reference the null-suppressed field in the superdescriptor. If you do not reference the null-suppressed field and the field has no data, there is no record in the index and optimization would return no records. To ensure correct results, FOCUS will not optimize the selection test if the null-suppressed field is not referenced.

See your Software AG documentation for more information about null-suppression and how it affects data retrieval.

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