Query tuning/planner method configuration v14

This section describes the configuration parameters used for planner method configuration.

edb_enable_pruning

Parameter type: Boolean

Default value: true

Range: {true | false}

Minimum scope of effect: Per session

When value changes take effect: Immediate

Required authorization to activate: Session user

When set to TRUE, edb_enable_pruning allows the query planner to early-prune partitioned tables. Early-pruning means that the query planner can prune (i.e., ignore) partitions that would not be searched in a query before generating query plans. This helps improve performance time as it eliminates the generation of query plans of partitions that would not be searched.

Conversely, late-pruning means that the query planner prunes partitions after generating query plans for each partition. (The constraint_exclusion configuration parameter controls late-pruning.)

The ability to early-prune depends upon the nature of the query in the WHERE clause. Early-pruning can be utilized in only simple queries with constraints of the type WHERE column = literal (e.g., WHERE deptno = 10).

Early-pruning is not used for more complex queries such as WHERE column = expression (e.g., WHERE deptno = 10 + 5).