SAS Data Set Options

BUFNO= Data Set Option

Specifies the number of buffers to be allocated for processing a SAS data set.

Valid in:	DATA step and PROC steps
Category:	Data Set Control
See:	BUFNO= Data Set Option in the documentation for your operating environment.

Syntax
Syntax Description
Details
Comparisons
See Also

Syntax

BUFNO= n | nK | hexX | MIN | MAX

Syntax Description

n | nK: specifies the number of buffers in multiples of 1 (bytes); 1,024 (kilobytes). For example, a value of 8 specifies 8 buffers, and a value of 1k specifies 1024 buffers.
hexX: specifies the number of buffers as a hexadecimal value. You must specify the value beginning with a number (0-9), followed by an X. For example, the value 2dx sets the number of buffers to 45 buffers.
MIN: sets the minimum number of buffers to 0, which causes SAS to use the minimum optimal value for the operating environment. This is the default.
MAX: sets the number of buffers to the maximum possible number in your operating environment, up to the largest four-byte, signed integer, which is 2³¹-1, or approximately 2 billion.

Details

The buffer number is not a permanent attribute of the data set; it is valid only for the current SAS session or job.

BUFNO= applies to SAS data sets that are opened for input, output, or update.

A larger number of buffers can speed up execution time by limiting the number of input and output (I/O) operations that are required for a particular SAS data set. However, the improvement in execution time comes at the expense of increased memory consumption.

To reduce I/O operations on a small data set as well as speed execution time, allocate one buffer for each page of data to be processed. This technique is most effective if you read the same observations several times during processing.

Operating Environment Information: The default value for BUFNO= is determined by your operating environment and is set to optimize sequential access. To improve performance for direct (random) access, you should change the value for BUFNO=. For the default setting and possible settings for direct access, see the BUFNO= data set option in the SAS documentation for your operating environment. [cautionend]

Comparisons

If the BUFNO= data set option is not specified, then the value of the BUFNO= system option is used. If both are specified in the same SAS session, the value specified for the BUFNO= data set option overrides the value specified for the BUFNO= system option.
To request that SAS allocate the number of buffers based on the number of data set pages and index file pages, use the SASFILE global statement.