NonStop SQL/MP Reference Manual

NonStop SQL/MP Reference Manual—142115
P-5
Examples—PAGE TITLE
Examples—PAGE TITLE
•
The following command defines a title for each page of a report:
S> TITLE "----- Accounts of: ", SALESREP, " -----" CENTER;
The title looks like this:
----- Accounts of: 220 -----
Parallel Index Loading
If you create an index on a base table that already contains data, SQL automatically
loads the index file with data from the base table. If the index is partitioned, you can
specify the PARALLEL EXECUTION option on the CREATE INDEX statement to
direct SQL to load partitions of the index in parallel. A similar clause on the LOAD
command serves the same function there.
When you execute CREATE INDEX or LOAD with the PARALLEL EXECUTION ON
option and the table being indexed or loaded is not empty, SQL starts a record generator
(RECGEN) process for each partition of the table and a sort process (SORTPROG) for
each partition of the index. Record generator processes read the base table. Sort
processes sort the rows and write them to the index.
The default location for the record generator program file is
$SYSTEM.SYSnn.RECGEN. You can specify a different location with the
=_SQL_RECGEN_node DEFINE.
Parallel processing uses more CPU cycles and disk processes at the same time than
serial (nonparallel) processing, and thus might temporarily monopolize system
resources.
For best performance, the disk processes for the volumes used should be distributed
evenly across all CPUs.
Specifying certain attributes of the =_SORT_DEFAULTS DEFINE can cause problems
with multiple sort processes. See the FastSort Manual for more information.
Default Configuration for Parallel Index Loading
You can use the PARALLEL EXECUTION clause to specify a configuration file that
describes attributes of record generator and sort processes. If you specify the
PARALLEL EXECUTION clause but do not specify a configuration file, SQL uses the
following defaults:
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Priority—Record generators and sort processes use the same execution priority as
the process that creates the index.
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CPU—If the partition is local, the record generator or sort process runs in the same
CPU that runs the primary disk process for the partition's disk. If that CPU is not
available or the partition is remote, the CPU is chosen arbitrarily and then in a
sequential, circular fashion. (Note that more than one record generator or sort
process might run in the same CPU.)