ECSMODE

Eon Mode only

Sets the ECS strategy that the optimizer uses when it divides responsibility for processing shard data among subscriber nodes. This hint is applied only if the subcluster uses elastic crunch scaling (ECS).

Syntax

SELECT /*+ECSMODE(option)*/

Arguments

*option*

Specifies the strategy to use when dividing shard data among its subscribing nodes, one of the following:

• AUTO: The optimizer chooses the strategy to use, useful only if ECS mode is set at the session level (see Setting the ECS Strategy for the Session or Database).

• IO_OPTIMIZED: Use I/O-optimized strategy.

• COMPUTE_OPTIMIZED: Use compute-optimized strategy.

• NONE: Disable use of ECS for this query. Only participating nodes are involved in query execution; collaborating nodes are not.

Example

The following example shows the query plan for a simple single-table query that is forced to use the compute-optimized strategy:

=> EXPLAIN SELECT /*+ECSMode(COMPUTE_OPTIMIZED)*/ employee_last_name,
             employee_first_name,employee_age
             FROM employee_dimension
             ORDER BY employee_age DESC;

                                   QUERY PLAN
--------------------------------------------------------------------------------
 ------------------------------
 QUERY PLAN DESCRIPTION:
 The execution of this query involves non-participating nodes.
 Crunch scaling strategy preserves data segmentation
 ------------------------------
. . .