POSC Specifications
Version 2.3
Relational Implementation Methodology

Projection and Data Integrity Recommendations

The following are POSC's recommendations regarding Epicentre relational projections:

  1. Projection operations which: 1) faithfully represent the logical model in a physical schema; and 2) allow for the implementation of a compatibility layer which completely hides the effects of the physical implementation from the logical level are valid. Only operations meeting these criteria may be applied to a logical subset to create a physical RDBMS schema.
  2. In a fully POSC compliant data store, Epicentre logical model rules (full and subset), and rules resulting from the application of projection operations must be maintained as meta data in a manner consistent with the requirements of the corresponding DAEF.
  3. In a POSC compliant data store, valid standard instance data for the subset of Epicentre represented by the data store must be maintained.
  4. Data store implementers should build DBMS triggers and other constructs to enforce POSC data integrity constraints where practical and indicate which constraints are not enforced by the DBMS.
  5. To ensure portability of data from an Epicentre subset to the full Epicentre model and/or other Epicentre subsets, application developers and/or direct SQL users must take responsibility for enforcing all data integrity constraints imposed by logical model rules and projection operations not enforced, for DAEF users, by the compatibility layer and, for direct SQL users, by the RDBMS.

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