Steps in Data Migration

Steps to Peacock Pond, Florida, Courtesy of Robert Smith, Australia

Steps in a General Approach to Data Migration

This Page describes a series of Steps in a General Approach to Data Migration between Source Systems and Target Systems.
It covers Extract, Transformation and Load.

There are no technical risks in Data Migration because it is a well-established procedure.
However, it is important to get User involvement right from the start, and
to get User sign-off at the end when all the Data has been successfully migrated.

Setting-up the Data Migration Process ...

Choose a Data Modelling Tool with Reverse Engineering Capability,(such as ERWin).
Define and create the Data Dictionary.
Identify all the required Data Sources, and an 'owner' for each Source.

Data Feeds
Legacy Systems
Operational Data Stores

Define the Data Items required, in consultation with the Users.
Create the Data Models for the Source Data.
Define Data Validation Checks (bottom-up) and Clean-Up Business Rules for Source Data.
Carry out an Audit of the Data Quality in major Databases, (bottom-up and top-down).
Define the Staging Area, with MIRror Tables to store Extract Files.
Create the Business Data Model for the Consolidated Database
If the final target is an ERP, such as SAP, then create the Data Model for the Target ERP Database
For SAP, J.D.Edwards, Peoplesoft and Siebel, a Modelling Tool called Saphir, from Silwood Technology
can be very useful here.
Define the Data Mapping between Source and Target Data Items.
Optionally, create a CRUD Matrix to identify the interactions between Data and Functions.
Define Acceptance Tests for data in the Integrated Database.
Executing the Data Migration Process.
1. Run Acceptance Tests on the Integrated Target Database,(esp. Referential Integrity).

There are not many books on Database Migration, but here are two :-

Migrating Legacy Systems, by Brodie and Stonebraker
Stonebraker is well-respected as the Architect of Ingres, but I didn't like this book very much.
At Amazon.com, but the only reviewer gave it 4 stars.
90 Days to the Data Mart, by Alan Simon.
This,of course,is devoted to Data Marts, but covers some common ground.
At Amazon.com, but the only reviewer gave this one 5 Stars.

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