The PSORT_NPROCS environment variable enables the
database server to improve the performance of the parallel-process
sorting package by allocating more threads for sorting.
Before the sorting package performs a parallel sort, make
sure that the database server has enough memory for the sort.
threads
is an integer, specifying the maximum number of threads to be
used to sort a query. This value cannot be greater than 10.
The following command sets PSORT_NPROCS to 4:
setenv PSORT_NPROCS 4
To disable parallel sorting, enter the following command:
unsetenv PSORT_NPROCS
It is recommended that you initially set PSORT_NPROCS to 2 when
your computer has multiple CPUs. If subsequent CPU activity is lower
than I/O activity, you can increase the value of PSORT_NPROCS.
Tip: If the PDQPRIORITY environment
variable is not set, the database server allocates the minimum amount
of memory to sorting. This minimum memory is insufficient to start
even two sort threads. If you have not set PDQPRIORITY, check
the available memory before you perform a large-scale sort (such as
an index build) to make sure that you have enough memory.