SAS Tips

SAS Features That Improve SAS System Performance

Is your SAS system not performing as efficiently as it could? Here is a list of SAS features that will improve SAS system performance. 

This list of SAS features is in no particular order:

1. Convert data that is used often to SAS 9.4 format
2. SAS accesses data in a SAS dataset more efficiently than ASCII format.  Where possible, use SAS dataset
3. To conserve memory usage when using array, use _TEMPORARY_  where possible.  This allows less memory and less time for memory allocation.
4. IF-THEN-ELSE is much more efficient than multiple IF-THEN statements in your SAS code.  Multiple IF-THEN forces each condition to be checked, whereas IF-THEN-ELSE statement if a condition is met the control returns to top of the structure without processing the ELSE clause; which may have multiple IF-THEN clauses in itself.
5. An efficient SAS code reduces file I/O; most resource expensive aspect.  Some features that help reduce SAS I.O are:
   a) Using SQL to subset and group data
   b)Use of WHERE clause to limit a data selection and processing
   c)Use of INDEXED data which allows the fastest access to an observation
6. Use of Scatter-Read/Gather-Write (SGIO) SAS System option in tandem with BUFNO option, allows SAS to read ahead number of pages specified by the BUFNO bypassing any intermediate buffer transfers placing it in memory for access before it is needed during a read or a write event in effect behaving like direct memory access.  For particular programs, experiment different BUFNO values to find the optimal setting.  Note: SGIO is not effective in UPDATE and or RANDOM mode. SGIO is effective for SAS I/O opened in UPDATE, INPUT, OUTPUT governed by sequential data access patten.