Among the factors that affect the interface performance
are the size of the table being accessed, the number of fields being
accessed, and the number of data records qualified by the selection
criteria. For tables that have many fields and many data records,
you should evaluate all SAS programs that need to access the table
directly. In your evaluation, consider the following questions:
-
Does the program need all the
CA-Datacom/DB fields? If not, create and use an appropriate
view descriptor that includes only the fields needed.
-
Do the selection criteria retrieve
only those data records needed for subsequent analysis? If not, specify
different conditions so that the selected records are restricted for
the program being used.
-
Is the data going to be used by more than one procedure in one SAS session? If so,
consider extracting the data and placing it in a
SAS data file for SAS procedures to use, instead of enabling the data to be accessed directly by
each procedure. See
Performance Considerations for circumstances in which extracting data is the more
efficient method.
-
Do the records need to be in a particular order? If so, include a SORT clause in
the appropriate
view descriptors or a SAS BY clause in a SAS program.
-
Do the selection criteria enable CA-Datacom/DB to use
key (indexed) fields and non-indexed fields efficiently? See
WHERE Clause in a View Descriptor for some guidelines on specifying efficient selection
criteria.
-
Does your WHERE clause cause
CA-Datacom/DB to create a temporary
index, which often requires excessive processing time? For more information about displaying
WHERE clauses and messages about creating temporary indexes, see
DDBTRACE= Data Set Option.
-
-
Are your CA-DATADICTIONARY elements well-matched to your view descriptors?
-
Would a different
URT help?
-
Would use of a default key give you a faster result?