Building the Data Warehouse

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SPECIAL CONSIDERATIONS: If the input to this step is incorrect or ambiguous, the amount of work required here can be much more than that estimated.

DELIVERABLE: Tables, databases physically designed.

Now the output from D3 and/or D4 is used to produce a physical database design. Some of the characteristics of the output include the following:

■■ Indexing

■■ Physical attribution of data ■■ Partitioning strategies ■■ Designation of keys

■    Clustering/interleaving

■■ Management of variable-length data

■    NULL/NOT NULL specification ■■ Referential integrity

The output of this step is the actual specification of the database to the DBMS or whatever data management software/conventions are adopted.

PARAMETERS OF SUCCESS: Done properly, this stage of analysis transforms all the considerations of logical design of data, performance, update, access, availability, reorganization, restructuring of data, and so on, into a workable database design.

Pl-Functional Decomposition

PRECEDING ACTIVITY: Requirements formalization.

FOLLOWING ACTIVITY: Context level 0 specification.

TIME ESTIMATE: Depends on the size of the system and degree of ambiguity (and how firmly and unambiguously the scope has been established). As a rule, two weeks for a reasonably sized system is adequate.

NORMALLY EXECUTED ONCE OR MULTIPLE TIMES: Once per phase of development.

From the requirements document comes the functional decomposition. The functional decomposition merely takes the broad function accomplished by the system and breaks it down into a series of successively smaller functions (down to a level sometimes called the primitive level).

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