SAS/ACCESS 9.2 for Relational Databases: Reference, Fourth Edition

318 DBSLICEPARM= Data Set Option 4 Chapter 11DBMS support: DB2 under UNIX and PC Hosts, DB2 under z/OS, HP Neoview, Informix,Microsoft SQL Server, ODBC, Oracle, Sybase, Sybase IQ, TeradataSyntaxDBSLICEPARM=NONE | THREADED_APPS | ALLDBSLICEPARM=( NONE | THREADED_APPS | ALL)DBSLICEPARM=( NONE | THREADED_APPS | ALL )Syntax DescriptionTwo syntax diagrams are shown here in order to highlight the simpler version. Inmost cases, the simpler version suffices.NONEdisables DBMS threaded reads. SAS reads tables on a single DBMS connection, as itdid with SAS 8 and earlier.THREADED_APPSmakes fully threaded SAS procedures (threaded applications) eligible for threadedreads.ALLmakes all read-only librefs eligible for threaded reads. It includes SAS threadedapplications, the SAS DATA step, and numerous SAS procedures.max-threadsspecifies with a positive integer value the maximum number of connections per tableread. A partition or portion of the data is read on each connection. The combinedrows across all partitions are the same irrespective of the number of connections.That is, changes to the number of connections do not change the result set.Increasing the number of connections instead redistributes the same result set acrossmore connections.There are diminishing returns when increasing the number of connections. Witheach additional connection, more burden is placed on the DBMS, and a smallerpercentage of time is saved in SAS. See the DBMS-specific reference section aboutthreaded reads for your interface before using this parameter.DetailsYou can use DBSLICEPARM= in numerous locations. The usual rules of optionprecedence apply: A table option has the highest precedence, then a LIBNAME option,and so on. A SAS configuration file option has the lowest precedence becauseDBSLICEPARM= in any of the other locations overrides that configuration setting.DBSLICEPARM=ALL and DBSLICEPARM=THREADED_APPS make SAS programseligible for threaded reads. To determine whether threaded reads are actuallygenerated, turn on SAS tracing and run a program, as shown in this example:options sastrace=’’,,,d’’ sastraceloc=saslog nostsuffix;proc print data=lib.dbtable(dbsliceparm=(ALL));where dbcol>1000;run;If you want to directly control the threading behavior, use the DBSLICE= data setoption.