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

316 DBSLICE= Data Set Option 4 Chapter 11DBSLICE= Data Set OptionSpecifies user-supplied WHERE clauses to partition a DBMS query for threaded reads.Default value: noneValid in: DATA and PROC steps (when accessing DBMS data using SAS/ACCESSsoftware)DBMS support: DB2 under UNIX and PC Hosts, DB2 under z/OS, HP Neoview, Informix,Microsoft SQL Server, ODBC, Oracle, Sybase, Sybase IQ, TeradataSyntaxDBSLICE=("WHERE-clause-1" "WHERE-clause-2" < ... " WHERE-clause-n">)DBSLICE=("WHERE-clause-1" " WHERE-clause-2" )Syntax DescriptionTwo syntax diagrams are shown here to highlight the simpler version. In manycases, the first, simpler syntax is sufficient. The optional server= form is valid only forDB2 under UNIX and PC Hosts, Netezza, and ODBC.WHERE-clauseThe WHERE clauses in the syntax signifies DBMS-valid WHERE clauses thatpartition the data. The clauses should not cause any omissions or duplications ofrows in the results set. For example, if EMPNUM can be null, this DBSLICE=specification omits rows, creating an incorrect result set:DBSLICE=("EMPNUM=1000")A correct form is:DBSLICE=("EMPNUM=1000" "EMPNUM IS NULL")In this example, DBSLICE= creates an incorrect set by duplicating SALES with avalue of 0:DBSLICE=(‘‘SALES=0’’)serveridentifies a particular server node in a DB2 partitioned database or in a MicrosoftSQL Server partitioned view. Use this to obtain the best possible read performanceso that your SAS thread can connect directly to the node that contains the datapartition that corresponds to your WHERE clause. See the DBMS-specific referencesection for your interface for details.DetailsIf your table reference is eligible for threaded reads (that is, if it is a read-onlyLIBNAME table reference), DBSLICE= forces a threaded read to occur, partitioning thetable with the WHERE clauses you supply. Use DBSLICE= when SAS is unable togenerate threaded reads automatically, or if you can provide better partitioning.DBSLICE= is appropriate for experienced programmers familiar with the layout oftheir DBMS tables. A well-tuned DBSLICE= specification usually outperforms SAS