The query optimization class is used
to direct the optimizer to use different degrees of optimization when
compiling SQL and XQuery queries.
This parameter provides
additional flexibility by setting the default query optimization class
used when neither the SET CURRENT QUERY OPTIMIZATION statement nor
the QUERYOPT option on the BIND command
are used.
- Configuration type
- Database
- Parameter type
- Configurable online
- Configurable by member in a DB2® pureScale® environment
- Propagation class
- Connection
- Default [range]
- 5 [ 0 - 9 ]
Note: The default value is subject to change by the DB2 Configuration Advisor after
initial database creation.
- Unit of measure
- Query Optimization Class (see the following list)
The query optimization classes currently defined
are:
- 0 - minimal query optimization.
- 1 - roughly comparable to DB2 Version 1.
- 2 - slight optimization.
- 3 - moderate query optimization.
- 5 - significant query optimization with heuristics
to limit the effort expended on selecting an access plan. This is
the default.
- 7 - significant query optimization.
- 9 - maximal query optimization
DB2 10.5 for Linux, UNIX, and Windows