SQL/MP Reference Manual

HP NonStop SQL/MP Reference Manual—523352-013
X-5
Considerations—=_SORT_DEFAULTS
param value
specifies a FastSort parameter and a value for that parameter. FastSort
parameters commonly used with NonStop SQL/MP are:
For information about other FastSort parameters and the parameters just
described, see the FastSort Manual.
Considerations—=_SORT_DEFAULTS

By using =_SORT_DEFAULTS, you can improve performance for DML operations
by giving the FastSort process sufficient space for sorting on an alternate disk
volume. Using =_SORT_DEFAULTS can also prevent errors caused when DML
operations encounter a full disk.

If the swap and scratch files you specify do not exist at the time of the FastSort
operation, FastSort creates them and uses MAXEXTENTS 160. If you create the
files yourself, you must choose an appropriate file size.

If you specify swap or scratch files on a LOAD command or in the configuration file
for parallel execution of a CREATE INDEX or LOAD command, those file
specifications override any file specifications in =_SORT_DEFAULTS for that
LOAD operation.

If SMF is installed on your node, you can specify either a virtual or physical volume
for the SCRATCH parameter. However, only physical volumes are valid values for
the SCRATCHON and NOSCRATCHON parameters.
If you specify a virtual volume for SCRATCH, the sort process ignores any overflow
scratch volumes you specify in SCRATCHON and NOSCRATCHON. Because
FastSort does not automatically create and manage overflow scratch files when
you specify a virtual volume for SCRATCH, the virtual volume must have space
available for all scratch files for the sort operation.
SCRATCH file specifies the Guardian name of a scratch file or
volume to store runs of records sorted by each
SORTPROG process. If you specify only a volume
name, FastSort automatically creates the scratch file;
this method is recommended for parallel sort
operations.
SWAP file specifies the Guardian name of a swap file or volume
for the extended memory segment. If you specify only
a volume name, FastSort automatically creates the
swap file; this method is recommended for parallel sort
operations.
VLM { ON | OFF } specifies use of additional memory for sorting;
improves performance in certain situations (usually for
LOAD, but not for CREATE INDEX). Do not use VLM
for parallel sort operations.