SQL/MX 3.1 Reference Manual (H06.23+, J06.12+)

Metadata Tables
HP NonStop SQL/MX Release 3.1 Reference Manual—663850-001
10-70
Query Optimization and Performance
MIN_MAX_OPTIMIZATION Set to ON or OFF. This performance optimization
enables the compiler to read only the result row or a
select number of rows to answer minimum (MIN) or
maximum (MAX) aggregate expressions. The
compiler can perform this type of optimization only
when the rows are naturally ordered on the MIN-
MAX column. If OFF, this type of optimization is
disabled.
The default is ON.
MSCF_ET_REMOTE_MSG_
TRANSFER
The value of this default is used to factor in the cost
of transferring messages to and from a remote node.
It reflects the bandwidth of the physical
communication link. You should set it to a value
greater than the cost factor of transferring messages
to or from a local node, which is 0.000046.
Allowable values: 1.175494351e-38 through
3.402823466e+038.
The default value is 0.00005.
MULTIUNION Set to ON, OFF, RESET, or SYSTEM. The default is
ON. When set to ON, NonStop SQL/MX generates a
MultiUnion node. When set to OFF, NonStop
SQL/MX does not generate a MultiUnion node.
When set to RESET or SYSTEM, the default value
is reset.
For information on the MultiUnion operator, see the
SQL/MX Query Guide.
NUMBER_OF_USERS Set to the number of users that can run concurrent
queries that use large amounts of memory. For
these queries, the optimizer uses this number to limit
the amount of memory available for one user. The
larger the number, the less memory available for
operators (such as hash join) that use much
memory.
Allowed values: 1 through 1,4294967295.
The default setting is 1, which means that all
available memory can be assigned to one query.
OLT_QUERY_OPT Set to ON or OFF. When set to ON, the NonStop
SQL/MX enables a fast path evaluation method for
certain simple SQL queries, such as a single table
unique select.
For additional information about this setting, see the
SQL/MX Query Guide.
The default is ON.
Attribute Setting