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

Threaded Reads 4 Summary of Threaded Reads 59thread. If three threads are specified for threaded reads, then three temporary spoolfiles are written.As the application requests subsequent passes of data, data is read from thetemporary spool files, not reread from the database. The temporary spool files can bewritten on different disks, reducing any disk read contention, and enhancingperformance. To accomplish this, the SAS option UTILLOC= is used to define differentdisk devices and directory paths when creating temporary spool files. There are severalways to specify this option:3 In the SAS config file, add the line:--utilloc("C:\path" "D:\path" "E:\path")3 Specify the UTILLOC= option on the SAS command line:on Windows:sas --utilloc(c:\path d:\path e:\path)on UNIX:sas --utilloc ’(\path \path2 \path3)’For more information about the UTILLOC= SAS option, see the SAS LanguageReference: Dictionary.When Threaded Reads Do Not OccurThreading does not occur under these circumstances:3 when a BY statement is used in a PROC or DATA step3 when the OBS or the FIRSTOBS option is in a PROC or DATA step3 when the KEY or the DBKEY option is used PROC or DATA step3 if no column in the table exists to which SAS can apply the MOD function. Formore information, see “Autopartitioning Techniques in SAS/ACCESS” on page 57.3 if all columns within a table to which SAS can apply the MOD function are inWHERE clauses. For more information, see “Autopartitioning Techniques in SAS/ACCESS” on page 57.3 if the NOTHREADS system option is set3 if DBSLICEPARM=NONESummary of Threaded ReadsFor large reads of table data, SAS threaded reads can speed up SAS jobs. They areparticularly useful when you understand the autopartitioning technique specific to yourDBMS and use DBSLICE= to manually partition only when appropriate. Look forenhancements in future SAS releases.