SPOOL= LIBNAME Statement Option

Specifies whether SAS creates a utility spool file during read transactions that read data more than once.

Valid in:	LIBNAME statement
Default:	YES
Supports:	All

Syntax

Details

Syntax

SPOOL=YES | NO | DBMS

Syntax Description

YES: specifies that SAS creates a utility spool file into which it writes the rows that are read the first time. For subsequent passes through the data, the rows are read from the utility spool file rather than being re-read from the data source table. This guarantees that the row set is the same for every pass through the data.

NO: specifies that the required rows for all passes of the data are read from the data source table. No spool file is written. There is no guarantee that the row set is the same for each pass through the data.

DBMS: is valid for Oracle only. The required rows for all passes of the data are read from the DBMS table but additional enforcements are made on the DBMS server side to ensure that the row set is the same for every pass through the data. This setting causes the Oracle driver to satisfy the two-pass requirement by starting a read-only transaction. SPOOL=YES and SPOOL=DBMS have comparable performance results for Oracle; however, SPOOL=DBMS does not use any disk space. When SPOOL is set to DBMS, the CONNECTION option must be set to UNIQUE. If not, an error occurs.

Details

In some cases, SAS processes data in more than one pass through the same set of rows. Spooling is the process of writing rows that have been retrieved during the first pass of a data read to a spool file. In the second pass, rows can be reread without performing I/O to the DBMS a second time. When data must be read more than once, spooling improves performance. Spooling also guarantees that the data remains the same between passes, as most data sources do not support member-level locking.

Teradata Details: SPOOL=NO requires SAS to issue identical SELECT statements to Teradata twice. Additionally, because the Teradata table can be modified between passes, SPOOL=NO can cause data integrity problems. Use SPOOL=NO with discretion.

MySQL Details: Do not use SPOOL=NO with the MySQL driver.