chap010 - Chapter 10 View Integration and Implementation...

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Chapter 10 View Integration and Implementation Compromises Review Questions R1. What three basic steps are involved in view integration? 1. Identify the common entities in two views. 2. Merge the common entities, resolving any entity conflicts and performing a set union of their attributes. 3. Examine each relationship and resolve any relationship conflicts. R2. What are two types of entity name conflicts that must be resolved when identifying common entities in multiple business process conceptual models? Two types of entity name conflicts include synonyms and homonyms. Synonyms are different labels (with equivalent meaning) used to represent the same entity. A homonym is a single label (with alternative meanings) used to represent different entities. R3. In view integration, what is attribute conflict and how is it resolved? Attribute conflict exists if different attributes have been identified as important for describing the same entity in various views. All necessary attributes of an entity set needed for all business processes in which that entity set occurs should be included in an enterprise-wide database. Attribute conflict is resolved by performing a set union of the attributes needed for the different cycles. R4. List and describe three conceptual level implementation compromises. 1. Exclusion of an entity or relationship because of inadequate measurement mechanisms or because no decision need exists for that data. 2. Consolidation of conceptually congruent entities. If two entities always occur in combination with each other, so that they are virtually indistinguishable, they may be combined into a single entity. 3. Materialization of tasks as event entities. Done when tasks are deemed sufficiently important to track separately from the events they comprise; not recommended, as it increases model complexity and results in a database design that must be changed if task workflow changes. 128 Solutions Manual to accompany Dunn, Enterprise Information Systems: A Pattern Based Approach, 3e
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Chapter 10 R5. List and describe three logical level implementation compromises. 1. Posting a foreign key into an entity table to represent a relationship in which the entity has optional participation. Should only be done when it will result in high load. Results in reduced query complexity and less overall use of space in database. 2. Combined entity key posting, i.e., the posting of a single foreign key to represent multiple relationships for which participation of the entity into whose table the key is posted is mutually exclusive. For example, a cash disbursement goes to a supplier or to a creditor or to an employee. Note: referential integrity cannot be enforced. 3. Combination of entity sets without generalization. For example, agents of
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This note was uploaded on 01/17/2011 for the course INFO SYSTE 115 taught by Professor Baker during the Spring '10 term at Strayer.

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chap010 - Chapter 10 View Integration and Implementation...

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