FastSort Manual

Sorting in Parallel
FastSort Manual—429834-003
6-5
Using FastSort Commands

An extended memory segment for each subsort process of at most 50 percent of
the processor’s physical memory not locked down by the operating system

A scratch file size for each subsort process equal to the output file size divided by
the number of subsort processes plus 6 bytes per record for overhead
FastSort computes the sizes of the extended memory segments and scratch files for
you.
Using FastSort Commands
To set up the automatic configuration with FastSort commands, use a SUBSORT
command for each subsort process before you issue the RUN command:
SUBSORT $VENUS
SUBSORT $MARS
SUBSORT $SATURN
For the best performance, each scratch file should be on a separate disk volume, and
the primary disk processes for the volumes should be running in different processors.
Using FastSort Procedures
To set up the automatic configuration using FastSort procedures, call the
SORTMERGESTART procedure and specify these items:

The number of subsort processes in the subsort-count parameter

An initial scratch file for each process in the scratch-file-name array

The flags parameter with bit 6 set to 1

A process-start array
For example, this call to SORTMERGESTART in a TAL procedure sets up a parallel
sort run with three subsort processes:
ERROR := SORTMERGESTART (sortblock,
keys,,
1,
indata,
,,,,
outdata,,,
flags,,
scratchfiles,,
startparams,,,,,
3);