Table 1.

CRDB design principles.

• Changes to data

Mediation approach should be used for data that changes often. Data warehousing approach should be used for data that changes periodically.

• Size of the data

Mediation approach should be used for larger data. Data warehousing approach should be used for smaller data.

• Availability of sources

Mediation approach should be used for sources that are always available. Data warehousing approach should be used for sources that are often unavailable.

• Required query processing time

Mediation approach should be used for data with flexible timing constraints. Data warehousing approach should be used for data with stringent timing constraints.

• Predictability of queries

Predictable queries on data that does not change often should be written in advance with the results stored in the warehouse. In addition, knowledge of the queries to be performed on the system should be taken into consideration during global schema design.