| SAS/ACCESS Interface to ADABAS Software |
Among the factors that affect ADABAS performance are the size of the
file being accessed, the number of data fields being accessed, and the number of logical records qualified by the selection criteria. For files that have many data fields and many logical records, you
should evaluate all SAS programs
that need to access the data directly. In your evaluation, consider the following questions:
- Do the selection criteria allow
ADABAS to use ADABAS descriptor data fields efficiently? See
Creating and Using View Descriptors Efficiently for some guidelines on specifying efficient selection criteria.
- Does the program need all
the ADABAS data fields? If not, create and use an appropriate view descriptor that includes only the data fields to be
used.
- Do the selection criteria retrieve only those logical records needed for subsequent analysis? If not, specify different conditions so that the selected
data are restricted for the program being used.
- Are the data going to be used by more than one procedure in a single SAS session? If so, consider extracting
the data and placing them in a SAS data file for SAS procedures to use, instead of allowing the data to be accessed directly by each procedure. See
Performance Considerations for circumstances when extracting data is the more efficient method.
- Do the data need to be
in a particular order? If so, include a SORT clause in the appropriate view descriptor or a SAS BY statement in the SAS program.
- What kind of locking
mechanism will ADABAS need to use? See Controlling Data Locks.
- Are
you using a view SORT clause, a SAS BY statement, or a SAS ORDER BY clause without either a view WHERE clause or a SAS WHERE clause? Without a WHERE clause, the engine qualifies
all
ADABAS data to be sorted, which can use a considerable amount of resources.
Copyright 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
