44 Generating Trace Information for Threaded Reads Chapter 6
--dbsliceparm ALL
Global SAS option that turns off threaded reads.
option dbsliceparm=NONE;
LIBNAME option that restricts threaded reads to just SAS threaded applications.
libname lib oracle user=scott password=tiger dbsliceparm=THREADED_APPS;
Table option that turns on threaded reads (with a maximum of three connections,
in the example below)
proc print data=lib.dbtable(dbsliceparm=(ALL,3));
where dbcol>1000;
run;
DBSLICE= and DBSLICEPARM= apply only to DBMS table reads. THREADS= and
CPUCOUNT= are additional SAS options that apply to threaded applications. For more
information about these options, see the
SAS Language Reference: Dictionary.
Generating Trace Information for Threaded Reads
A threaded read is a complex feature. A SAS step can be eligible for a threaded read,
but not have it applied. Performance effect is not always easy to predict. Use the
SASTRACE option to see if threaded reads occurred and to help assess performance.
The following examples demonstrate usage scenarios. Keep in mind that trace output
changes from release to release.
/*Turn on SAS tracing */
options sastrace=’’,,,d’’ sastraceloc=saslog nostsuffix;
/* Run a SAS job */
data work.locemp;
set trlib.MYEMPS;
run;
When autopartitioning finds a partitioning column, tracing produces the following
type of message:
DBSLICEPARM enabled. Option value to set for DBSLICE is ({FN MOD
({FN ABS("NUMCLASS")}
2)}= 0 OR "NUMCLASS" IS NULL)
DBSLICEPARM enabled. Option value to set for DBSLICE is ({FN MOD
({FN ABS("NUMCLASS")}
2)}= 1 OR "NUMCLASS" IS NULL)
If a threaded read cannot be done either because all of the candidates for
autopartitioning are in the WHERE clause or because the table does not contain a
column that fits the criteria, you will see a warning in your log. For example:
data work.locemp;
set trlib.MYEMPS(DBSLICEPARM=ALL);
where EMPNUM<=30 and ISTENURE=0 and SALARY<=35000 and NUMCLASS>2;
run;
