Abstract: In an example method, a presence of a component with a cryptographic identity is detected. The component is detected by an authenticator component capable of authenticating a component. The example method further includes determining an authentication status of the detected component. The authentication status of the component is added to an extensible list of volatile, runtime data. Further, the authenticator component signs the extensible list with a private key to create a group identity. Finally, the authenticator component sends the group identity to a next higher component in an authentication hierarchy.

Abstract: Multiple cost models (e.g., a sub-operations costing model and logical-operations costing model) can be used to make cost estimations of execution of database queries in one and each one of the multiple heterogeneous database systems. As a result, a “hybrid” cost estimating mode can be used whereby two or more cost models can be used in a single database system in to order maximize the advantages and minimize the disadvantages of each of the cost models, thereby striving to achieve an optimal balance. In addition, cost estimation can be switched between a hybrid cost estimating mode and a single cost estimating mode. The switch can, for example, be made as a part of tuning phase, as more information about actual costs of execution of database queries becomes more available, or as a result of changes to the database system and/or it operations, and so on. As a result, a flexible cost estimating mechanism can also be provided.