Data Migration

Data Migration is the process of transferring data between one system to another system. Data migration is required when organizations or individuals change computer systems or upgrade to new systems, or when systems merge (such as when the organizations that use them undergo a merger/takeover).

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

Oracle Data & Migration

The sets of data required by Oracle Applications can be broadly classified in to 4 categories

  • Master Data : Item, Customer, Vendor, Bank Accounts, etc.
  • Opening Balances: On-Hand Quantity of Items, GL Balances, etc.
  • Open Transactions : Open Purchase Orders, Open Sales Order, Open Invoice etc.
  • Set-up Data :  Item Categories, Stock Locators
Similary source of data can be classified as
  • Existing Applications : DB2, Tally, SMS, etc.
  • Electronic Data : Comming through EDI in formats of Excel, Word, etc.
  • Hard Copy Data : In Registers
  • Non - Existent : Equipment Master, Collect and then migrate
The above diagram depicts the high level Data Migration approach from Legacy to ORACLE.

At a minimum, the data migration from Legacy to ORACLE consists of these tasks:
  • Extracting the data from Legacy data base.
  • Loading the extracted data into staging area.
  • Mapping and transformation of source data.
  • Migrating source data from staging area into target data base.

Important APIs/Open Interfaces

Customer APIs
Org Contact Role Hz_party_contact_v2pub.Create_Org_Contact_Role
Customer Profile HZ_CUSTOMER_PROFILE_V2PUB. create_customer_profile
Customer Profile Amount HZ_CUSTOMER_PROFILE_V2PUB. create_cust_profile_amt
Customer Credit Rating HZ_PARTY_INFO_V2PUB.create_credit_rating
Customer Contact Role HZ_CUST_ACCOUNT_ROLE_V2PUB.create_role_responsibility

Vendor APIs

Item Import
You must import items into the Item Master organization before you import items into additional organizations. You can accomplish this by specifying only your Item Master organization on a first pass run of the Item Interface. Once this has completed, you can run the Item Interface again, this time specifying an additional or all organizations.
Populate these tables first..
Always set the TRANSACTION_TYPE column to CREATE, to create an item record (true when both importing a new item and assigning an already existing item to another organization). This is the only value currently supported by the Item Interface.Set the PROCESS_FLAG to 1 (Pending), so that the Item Interface can pick up the row and process it.The program sets the PROCESS_FLAG to 7 (Import succeeded) or  4 (Import failed) or  3 (validation failed). A row is inserted into the MTL_INTERFACE_ERRORS table for all failed rows.When the Item Interface imports an item, it also assigns the item to the mandatory category sets based on the item defining attributes. The default category for each category set is used. The Item Interface also allows you to assign items to other category sets and categories, when there is data for item category assignments in the MTL_ITEM_CATEGORIES_INTERFACE table.
Run Import Items Report :
Indicate whether to run the interface for all organizations in the item interface table. If you choose No, the interface runs only for the current organization and interface table rows for other organizations are ignored.Parameter Create or Update Items..
1 Create new items.
2 Update existing items.

Transaction/Journal Migration

The migration of transactions & journals from legacy to oracle is the most difficult part of data migration. You should migrate all the GL balance for the current year periods, all the last year periods and the ending balance of ‘Y-2’ to oracle. You need to do a proper reconciliation of GL balances after migration of open AP/AR invoices to the current period.

AP Open Invoice
The charge and tax amounts of the open AP invoices already exist in the legacy system. You need to make sure that you don’t account them again in oracle.
Accounting entries in Legacy
Charge A/C Dr
Tax  A/C Dr                            Supplier Liability A/C Cr

Instead of the liability account use a clearing account(Liability) while transferring the journals to oracle GL. Make the below changes while transferring these journals to oracle GL
Charge A/C Dr
Tax  A/C Dr                           
Migration Clearing A/C (Liability) Cr

When you transfer the AP invoice from legacy to oracle. Use the above migration clearing account as charge/tax/freight A/C
Accounts created in oracle AP

Migration Clearing A/C (charge)
Migration Clearing A/C(tax)                       Supplier Liability A/C Cr

Transfer these accounts from AP to Oracle GL. After posting all these journals in the current period the YTD balance of migration clearing A/C should be zero.

AR Open Invoice
Similar to AP open invoice in AR invoice we use a clearing account (ASSET) instead of the receivable A/C in legacy. The revenue and tax amounts of the open AR invoices exist in the legacy system. You need to make sure that you don’t account them again in oracle.

Accounting entries in Legacy
Receivable A/C Dr
                                    Revenue A/C Cr                           
                                    Tax A/C Cr            
Make the below changes while transferring these journals to oracle GL
Migration Clearing A/C (Asset) Dr
                                                             Revenue A/C Cr                           
                                                              Tax A/C Cr     

When you transfer the AR invoice from legacy to oracle. Use the above migration clearing account as revenue/tax/freight A/C (use transaction type in auto accounting and put the clearing accounts in transaction type)
Accounts created in oracle AR

Receivable A/C Dr
                                    Migration Clearing A/C (Revenue) Cr                           
                                     Migration Clearing A/C (Tax) Cr            

Transfer these accounts from AR to Oracle GL. After posting all these journals in the current period the YTD balance of migration clearing A/C should be zero.

Fixed Assets
Transfer all the assets from legacy to oracle with Accumulated depreciation till the current period. Oracle ‘ll not create any depreciation for previous period. System ‘ll create below journal entries when you close & transfer the journals for the first asset period

Addition Journals
Addition Cost A/C Dr.
                                  Addition Cost Clearing A/C  Cr.
All these assets are present in legacy GL and transferred as a part of GL migration. You need to reverse all these journals in current period

Depreciation Journals
System‘ll create the depreciation journals for the current period.
All the past period depreciation & acc. Depreciation amounts are transferred through GL migration.