Adaptive Server provides the following predefined execution classes:
EC1 – has the most preferred attributes.
EC2 – has average values of attributes.
EC3 – has non-preferred values of attributes.
Objects associated with EC2 are given average preference for engine resources. If an execution object is associated with EC1, Adaptive Server considers it to be critical and tries to give it preferred access to engine resources.
Any execution object associated with EC3 is considered to be least critical and does not receive engine resources until execution objects associated with EC1 and EC2 are executed. By default, execution objects have EC2 attributes.
To change an execution object’s execution class from the EC2 default, use sp_bindexeclass, described in “Assigning execution classes”.