NonStop SQL/MP Reference Manual

NonStop SQL/MP Reference Manual—142115
Z-7
Considerations—=_SQL_CMP_CPUS_node
DEFINE is in effect. To specify a different set of available CPUs for a new parallel
query, reset the DEFINE.
=_SQL_CMP_CPUS_node affects only the location of Executor Server Processes
(ESPs) for parallel plans. It does not affect the location of the master executor.
=_SQL_CMP_CPUS_node also has no effect upon the following:
°
Locations of sort processes used in the query
°
Locations of disk processes used in the query
•
Specifying the CPU configuration—mapping binary code to hex code
=_SQL_CMP_CPUS_node syntax requires that you express a configuration of
CPUs to use for the parallel query as a string of up to four hex characters.
The following example shows how to express the configuration as binary code, then
how to map the binary code to hex code. It assumes there are 16 CPUs on the
current node and that CPUs 0, 1, 2, 3, 8, 10, 12, and 15 are available.
First, assign each CPU number a “1” if it is available or a “0” if it is not available, as
follows:
The CPUs in this example are shown in groups of four, because each hex character
represents four CPUs, as follows:
Using this binary-to-hex conversion chart, the first group of four CPUs-0, 1, 2, and
3-with the binary code “1111” map to the single hex character “F.” Mapping binary
codes for the remaining three groups of CPUs yields the hex characters “0,” “A,”
and “9,” respectively. Therefore, the complete hex character expression for this CPU
configuration is “F0A9.” The =_SQL_CMP_CPUS_node syntax for this
configuration is:
ADD DEFINE =_SQL_CMP_CPUS, CLASS MAP, FILE XU0A9;
For nodes with fewer than 16 CPUs, SQL assumes that the missing trailing hex
characters are zero.
CPU #: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Binary (ON/OFF) value: 1 1 1 1 0 0 0 0 1 0 1 0 1 0 0 1
Hex Binary Hex Binary
0 0000 8 1000
1 0001 9 1001
2 0010 A 1010
3 0011 B 1011
4 0100 C 1100
5 0101 D 1101
6 0110 E 1110
7 0111 F 1111