lecture 09 - migration to the architected environment

7/29/2019 Lecture 09 - Migration to the Architected Environment

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Building Data WareHouse

by InmonChapter 09: Migration to the Architected Environment

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9. Migration to the Architected

Environment1. A Migration Plan

2. The Feedback Loop

3. Strategic Considerations

4. Methodology and Migration

5. Summary



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9.1A Migration Plan

Beginning point: Data Model-represents the information needs ofthe corporation.

Data Model needs to identify at aminimum: Major subjects of the corporation

Definition of the major subjects of the

corporation Relationships between the major subjects

Groupings of keys and attributes thatmore fully represent the major subjects


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9.1A Migration Plan (ct.)

After having the corporate data model,the next activity is defining the system of

record.

It is nothing more than the identificationof the best data that the corporation

has:

Most timely

Most accurate

Most complete

Nearest to the external source

Most structurally compatible


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Technological challenges in bringingthe system-of-record data into the

DW:

A change in DBMSA change in operating systems

The need to merge data from different

DBMSs and operating systems The capture of the Web-based data in the

Web logs

A change in basic data formats


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After the system of record is defined, thenext step is to design the datawarehouse.

The following things need to be done: An element of time needs to be added to the

key structure if one is not already present.

All purely operational data needs to beeliminated.

Referential integrity relationships need to beturned into artifacts.

Derived data that is frequently needed isadded to the design.


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After the data warehouse is designed,the next step is to design and build theinterfacesbetween the system of recordand the DW.

Interfaces activities: Being an extract process

Integration of data from the operational,

application-oriented environmentAlteration of the time basis of data

Condensation of data

Efficient scanning of the existing systems

environment


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Once the interface programs aredesigned and built, the next activity isto start thepopulation of the first

subject area: The first of the data is read in the legacy

environment; and then it is captured andtransported to the data warehouse

environment. Directories are updated

Metadata is created

Indexes are made



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Caution: If you

wait for existingsystems to be

cleaned up, you

will neverbuild adata warehouse


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9.2 The Feedback Loop

At the heart of success in the long-termdevelopment of the data warehouse is thefeedback loop between the data architect andthe DSS analyst.

The DSS analyst: uses the data warehouse as a basis for

analysis

conveys those requirements to the data

architect The data architect:

add data, delete data, alter data, and so forthbased on the recommendations of the DSS

analyst http://it-slideshares.blogspot.com


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9.2 The Feedback Loop

(ct.)



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9.3 Strategic

Considerations

The DW

environment is

designed and builtfor the purpose of

supporting the DSS

needs of the

organization.



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9.3 Strategic Considerations

(ct.)

Besides that, the

corporation has

operational needsas well.

But the

operational world

is shown as beingin a state of

chaos.



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(ct.) The steps the data architect takes to

restructure the operational

environment:

Create a delta list The impact analysis

Create the resource estimate

All the preceding are packaged in a reportthat goes to information systems

management.



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(ct.) Operation cleanup plan:


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9.4 Methodology and Migration

The methodology for the building ofthe data warehouse is called a spiral

developmentmethodology.

The spiral methodology not onlycontains information about how to

build a data warehouse, but also

describes how to use the datawarehouse.



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9.4 Methodology and Migration

(ct.) The differences between the waterfall

approach and the spiral approach:


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9.5 Summary

The starting point for the design of the datawarehouse is the corporate data model,.

The data warehouse is built iteratively.

The development approach for the datawarehouse environment is said to be an

iterative or a spiral development approach.

The feedback loop between the data

architect and the end user is an importantpart of the migration process.

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lecture 09 - migration to the architected environment

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