currentExplainMode
Specifies the value for the CURRENT EXPLAIN MODE special register. The
CURRENT EXPLAIN MODE special register enables and disables the Explain
facility. The data type of this property is String. The maximum length is 254
bytes. This property applies only to connections to data sources that support
the CURRENT EXPLAIN MODE special register, such as DB2 Database for
Linux, UNIX, and Windows.
currentExplainSnapshot
Specifies the value for the CURRENT EXPLAIN SNAPSHOT special register.
The CURRENT EXPLAIN SNAPSHOT special register enables and disables the
Explain snapshot facility. The data type of this property is String. The
maximum length is eight bytes. This property applies only to connections to
data sources that support the CURRENT EXPLAIN SNAPSHOT special
register, such as DB2 Database for Linux, UNIX, and Windows.
currentQueryOptimization
Specifies a value that controls the class of query optimization that is performed
by the database manager when it binds dynamic SQL statements. The data
type of this property is int. The possible values of currentQueryOptimization
are:
0 Specifies that a minimal amount of optimization is performed to
generate an access plan. This class is most suitable for simple dynamic
SQL access to well-indexed tables.
1 Specifies that optimization roughly comparable to DB2 Database for
Linux, UNIX, and Windows Version 1 is performed to generate an
access plan.
2 Specifies a level of optimization higher than that of DB2 Database for
Linux, UNIX, and Windows Version 1, but at significantly less
optimization cost than levels 3 and above, especially for very complex
queries.
3 Specifies that a moderate amount of optimization is performed to
generate an access plan.
5 Specifies a significant amount of optimization is performed to generate
an access plan. For complex dynamic SQL queries, heuristic rules are
used to limit the amount of time spent selecting an access plan. Where
possible, queries will use materialized query tables instead of the
underlying base tables.
7 Specifies a significant amount of optimization is performed to generate
an access plan. This value is similar to 5 but without the heuristic
rules.
9 Specifies the maximum amount of optimization is performed to
generate an access plan. This can greatly expand the number of
possible access plans that are evaluated. This class should be used to
determine if a better access plan can be generated for very complex
and very long-running queries using large tables. Explain and
performance measurements can be used to verify that a better plan has
been generated.
optimizationProfile
Specifies an optimization profile that is used during SQL optimization. The
data type of this property is String. The optimizationProfile value is used to set
the OPTIMIZATION PROFILE special register. The default is null.
Chapter 7. JDBC and SQLJ reference information 227
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