To achieve an effective data migration in oracle, data on the old system is mapped to the oracle database format. Data migration may involve many phases but it minimally includes data extraction where data is read from the old system and data loading where data is written to the oracle system.
After loading into Oracle, results are subjected to data verification to determine whether data was accurately translated, is complete, and supports processes in the new system. During verification, there may be a need for a parallel run of both systems to identify areas of disparity and forestall erroneous data loss.
Automated and manual data cleaning is commonly performed in migration to improve data quality, eliminate redundant or obsolete information, and match the requirements of the new system. Data migration phases (Design, Extraction, Cleansing, Load, Verification) for applications of moderate to high complexity are commonly repeated several times before the new system is deployed.
Data conversion is a bit different from data migration in the sense that in data conversion we convert data form one format to another format in the different version of the same system. Example: When we upgrade from Oracle 11i to Oracle R12 we do a data conversion from 11i to R12
Interface is similar to both the data migration and conversion in the sense it involves the movement of data from one system to another system but its requirement in business is completely different. Interfaces are written to transfer data on a regular basis where as most of the data migration and conversion job are one time activity.
Following examples distinguishes all the above three process
- Importing customer / supplier / item information from legacy – Data Migration
- Moving customer / supplier / item information from 11i to R12 – Data Conversion
- Importing/Exporting PO/SO/WIP information from one system to oracle on a daily basis – Interface Job