database design and implimentaion
TRANSCRIPT
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The Database Design And Implementation
Process
• Shashwat Shriparv• [email protected]• InfinitySoft
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Phase 2a (continued…)
For large databases with many expected users and applications, the view integration approach of designing individual schema and merging them can be used.
Schema (view) integration
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Schema integration has following subtask:
1: Identifying correspondences and conflicts
among the schema:Because the schemas are individually
designed, it is necessary to specify construct the schema that represent real world concept.
a) Naming conflicts Two types:- 1)SYNONYMS
different name same concept 2)HOMONYMS
same name different concept
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b) Type conflicts:
Same concepts represented in two schemas by different modeling constructs
c) Domain conflicts:
An attribute may have different domains in two schemas.
d) Conflicts among Constraints:
Two Schemas may impose different constraints
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2.Modifying views to conform to one another: Some schema are modified so
that they conform other schema closely. Conflicts that are identified in subtask one are resolved during this step.
3.Merging views:Global scheme are created by
merging individual schema. Corresponding concepts are represented once in resulting schema and mapping between the views are done.
4.Restructuring:This is an optional step and is
done to avoid redundancies or unnecessary complexity.
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Merged view
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Taking into consideration the complexity of merging process and to get the exact meaning of the schema after merging, there are several strategy proposed…
Strategies for Merging
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1.Binnary ladder integration.
Two schema quite similar are integrated first, then the resulting schema with another similar schema and so on…the ordering depend on the measure of similarity
V1V2
V 3
V5
V4
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2.N-ary integration
All schemas are integrated at one stretch using a single procedure after the analysis of the correspondences
V1 V2 V 3 V4 V5
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3.Binary balanced strategy:
Pairs of schema are integrated first ,then the resulting schema are paired for further integration.
V1 V2
V5V4
V3
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4.Mixed strategy:
The schemas are portioned into groups based on their similarity and each group is integrated separately
V1
V 3V5
V4
V6
4.Mixed strategy:
The schemas are portioned into groups based on their similarity and each group is integrated separately
V1V2
V 3V5
V4
V6
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Phase 2b
The purpose of this phase is to design the characteristics of known database transactions in a DBMS-independent way…Designers are aware of many transactions that will run, once database is implemented.Important part database design is to specify its functional characteristics of these transactions. Usually, some database transaction are known at design time; after database is implemented, newer transactions are identified and implemented.
Transaction Design
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Transaction are usually grouped into 3 categories.
1). Retrieval transaction.Retrieves data.
2). Update transaction.Update data.
3). Mixed transaction. mixture of retrieval and update
transaction
