Migrate datas from RDB to Oracle 10g

Question

The applications that use the RDB database are being re-write with Forms based on an Oracle database.
Of course, before we use the new application, we will have a step for moving datas from old tables in Rdb to the new tables (new design) in Oracle (developpers are working on sql scripts for that). But when the new applications with Oracle db will be in production, I would like to save datas (datas as datas) from Rdb in an Oracle database with the same struture as the rdb structure (same tabels, with same columns and same datas in). The idea is we will be able to verify datas through SQL.
Do you have any idea ?
Thank you
AnneMar

Answer 1

Hi AnneMar,
there exists a Metalink note that serves as a starter for such a migration:
Note 135929.1: RDBPROD: Advice on Converting from Oracle Rdb to Oracle RDBMS
For your convenience I am pasting that note here.
Regards
Wolfgang
PURPOSE
To provide general advice on migrating from Oracle Rdb to Oracle RDBMS
SCOPE & APPLICATION
This advice is intended for people who have already decided to convert, and are starting to plan how to do it. It provides a broad outline of how it can be done and some of the things to consider.
Advice on Converting from Oracle Rdb to Oracle RDBMS
General notes
* The longer you leave it the easier it is likely to be. The SQL interfaces to Rdb are growing closer to those for RDBMS, particularly OCI Services for Rdb.
* Converting the database will probably be the easy part. The applications are likely to require more work.
* A staged approach is more likely to be successful than trying to do everything in one go.
A possible strategy for converting
1. Install OCI Services for Rdb. Pick a small application, or one that needs rewriting anyway. Convert the application using the method and tools of your choice to access the Rdb database via SQL*Net for Rdb. If unsatisfied with the results, you can repeat this with alternative methods or tools, until you find one that works for you.
2. Install RDBMS. For those tables used by applications converted to use OCI Services, create database links. Point the converted application to the RDBMS database instead of the Rdb one. This step can be done whilst other applications are being converted. No data is yet stored in the RDBMS database, so any problems that arise with it, possibly due to lack of appropriate DBA experience, can be worked around by just pointing the programs back at the Rdb database.
3. Now you have a choice.
1. Gradually move the data into the RDBMS database. First new tables, then tables only accessed by applications that have already been converted. This has the advantage of taking one step at a time, so it would be easy to back up temporarily if a problem is found. The main disadvantage is that now that the data is spread over two databases your backup and recovery strategy will be more complicated.
2. Finish converting the applications. Then transfer all the data over in one go. If there is a lot of data, then going back would be a big job, so there is more risk.
Alternative common interfaces
Besides OCI Services there are several other APIs that applications could use to access Rdb or RDBMS transparently.
* JDBC - If your applications are written in JAVA or you want to rewrite them in JAVA
* ODBC - If your applications run on Windows
* .NET - If your applications run on Windows
Techniques for converting a database
* Transferring Metadata Extract the metadata using RMU/EXTRACT. Cut down and edit the output to produce a script to use to create the corresponding RDBMS objects.
* Transferring data
For small tables,
INSERT INTO rdbms_table SELECT columns FROM rdb_table;
(using dblinks to the rdb database and SQL*Net for Rdb)
For large tables, use RMU/UNLOAD to create a delimited file and then load that into RDBMS using SQL$Loader.
* Keeping data current in RDBMS while testing the transfer can be done using the Logminer Option in Rdb.
Notes
1. OCI Services for Rdb was formerly known as SQL*Net for Rdb and is part of Oracle SQL/Services. Though this is structured as a separate product from Oracle Rdb no additional license is needed.
2. Some limits are different between Rdb and RDBMS.
For example: in Rdb table and column names can be 31 bytes but RDBMS only allows 30.
3. The RMU/EXTRACT command can write the SQL definitions of objects within a Rdb database to a text file.
RELATED DOCUMENTS
SQL*Net for Rdb
Oracle Rdb Guide to SQL*Net for Rdb
Oracle Rdb Oracle SQL/Services Release Notes
Oracle Rdb A Comparison of SQL Dialects for Oracle and Oracle Rdb
RMU/EXTRACT and /UNLOAD
Oracle RMU Reference Manual
SQL*Loader
Oracle8 Server Utilities