Controls the scope of DBMS threaded Reads and the number of threads.
| Valid in: | configuration file, SAS invocation, OPTIONS statement, SAS System Options window |
|---|---|
| Category: | System Administration: Performance |
| Default: | THREADED_APPS, none [Greenplum, HAWQ] |
| THREADED_APPS,2 [DB2 under z/OS, Oracle, Teradata] | |
| THREADED_APPS,2 or THREADED_APPS,3 [DB2 under UNIX and PC Hosts, Informix, Microsoft SQL Server, ODBC, SAP ASE, SAP IQ] | |
| Restriction: | Teradata: Starting in SAS 9.4M9, do not specify the value ALL. This option is not supported for Teradata on z/OS. Instead, set FASTLOAD=YES. |
| Interaction: | Google BigQuery: To specify this option, you must also set READ_MODE=STORAGE for a table or a LIBNAME connection. |
| Data source: | DB2 under UNIX and PC Hosts, DB2 under z/OS, Google BigQuery, Greenplum, HAWQ, Informix, Microsoft SQL Server, ODBC, Oracle, SAP ASE, SAP IQ |
| Note: | Support for Google BigQuery was added in SAS 9.4M9. |
| See: | DBSLICE= data set option, DBSLICEPARM= LIBNAME option, DBSLICEPARM= data set option, SLEEP= LIBNAME option, SLEEP= data set option, TENACITY= LIBNAME option, TENACITY= data set option |
Table of Contents
disables DBMS threaded Read. SAS reads tables on a single DBMS connection, as it did with SAS 8 and earlier.
makes fully threaded SAS procedures (threaded applications) eligible for threaded Reads.
makes all read-only librefs eligible for threaded Reads. This includes SAS threaded applications, as well as the SAS DATA step and numerous SAS procedures.
| Restriction | Teradata: Starting in SAS 9.4M9, do not specify the value ALL. |
|---|
a positive integer value that specifies the maximum number of connections per table read. The second parameter of the option determines the number of threads to read the table in parallel. The number of partitions on the table determine the number of connections made to the Oracle server for retrieving rows from the table. A partition or portion of the data is read on each connection. The combined rows across all partitions are the same regardless 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 across more connections.
There are diminishing returns when increasing the number of connections. With each additional connection, more burden is placed on the DBMS, and a smaller percentage of time saved on the SAS step. See the DBMS-specific reference section for details about partitioned reads before using this parameter.
You can use DBSLICEPARM= in numerous locations. The usual rules of option precedence apply: A table option has the highest precedence, then a LIBNAME option, and so on. SAS configuration file option has the lowest precedence because DBSLICEPARM= in any of the other locations overrides that configuration value.
DBSLICEPARM=ALL and DBSLICEPARM=THREADED_APPS make SAS programs eligible for threaded Reads. To see whether threaded Reads are actually generated, turn on SAS tracing and run a program, as shown in this example.
options sastrace=",,t" 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 set option.
DB2 under UNIX and PC Hosts, Informix, Microsoft SQL Server, ODBC, SAP ASE, SAP IQ: The default thread number depends on whether an application passes in the number of threads (CPUCOUNT=) and whether the data type of the column that was selected for data partitioning is binary.
Greenplum, HAWQ: There is no default value for the maximum number of connections per table read. This value depends on the number of partitions in a table and on arguments that are used with the MOD function in a WHERE clause. For more information, see Autopartitioning Techniques in SAS/ACCESS.
Here is how to use DBSLICEPARM= in a SAS configuration file entry in Windows to turn off threaded Reads for all SAS users.
-dbsliceparm NONEHere is how you can use DBSLICEPARM= as a z/OS invocation option to turn on threaded Reads for read-only references to DBMS tables throughout a SAS job.
sas o(dbsliceparm=ALL)option dbsliceparm=(threaded_apps,3);You can use DBSLICEPARM= as a LIBNAME option to turn on threaded Reads for read-only table references that use this particular libref, as shown in this example.
libname dblib oracle user=myusr1 password=mypwd1 dbsliceparm=ALL;Here is how to use DBSLICEPARM= as a table-level option to turn on threaded Reads for this particular table, requesting up to four connections.
proc reg SIMPLE;
data=dblib.customers (dbsliceparm=(all,4));
var age weight;
where years_active>1;
run;