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:
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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.
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Do the selection criteria retrieve
only those logical records needed for subsequent analysis? If not,
specify different conditions so that the selected data is restricted
for the program being used.
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Is the data going to be used by
more than one procedure in a single SAS session? If so, consider
extracting the data and placing it in a SAS data file for SAS procedures
to use, instead of letting the data to be accessed directly by each
procedure. See
Performance Considerations for circumstances when extracting data is the more efficient
method.
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Does 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.
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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.