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

800 Passing Joins to Teradata 4 Chapter 283 TRIMDATETIME, SOUNDEX, and TIME are not entirely compatible with thecorresponding SAS functions. Also, for SOUNDEX, although Teradata always returns 4characters, SAS might return more or less than 4 characters.Passing Joins to TeradataFor a multiple libref join to pass to Teradata, all of these components of theLIBNAME statements must match exactly:3 user ID (USER=)3 password (PASSWORD=)3 account ID (ACCOUNT=)3 server (TDPID= or SERVER=)You must specify the SCHEMA= LIBNAME option to fully qualify each table namein a join for each LIBNAME that you reference.For more information about when and how SAS/ACCESS passes joins to the DBMS,see “Passing Joins to the DBMS” on page 43.Maximizing Teradata Read PerformanceOverviewA major objective of SAS/ACCESS when you are reading DBMS tables is to takeadvantage of the Teradata rate of data transfer. The DBINDEX=, SPOOL=, andPREFETCH= options can help you achieve optimal read performance. This sectionprovides detailed information about PREFETCH as a LIBNAME option andPREFETCH as a global option.Using the PreFetch FacilityOverviewPreFetch is a SAS/ACCESS Interface to Teradata facility that speeds up a SAS job byexploiting the parallel processing capability of Teradata. To obtain benefit from thefacility, your SAS job must run more than once and have these characteristics:3 use SAS/ACCESS to query Teradata DBMS tables3 should not contain SAS statements that create, update, or delete Teradata DBMStables3 run SAS code that changes infrequently or not at all.In brief, the ideal job is a stable read-only SAS job.Use of PreFetch is optional. To use the facility, you must explicitly enable it with thePREFETCH LIBNAME option.