Challenges in migrating from IBM DB2 to Netezza

Question

Due to added advantage of high performance and reduction in turnaround time, I am trying to migrate all the data from IBM DB2 to Netezza in my organization.

But what I realized is there is no concept of primary key in Netezza? If true, I can try and take care of these issue by using duplicate removal stage in Datastage.

Also, could you guys please assist me understanding if there are any more constraints that I should consider or challenges I could face for DB2 to Netezza migration?

Answer 1

Netezza does allow you to specify Primary Key and Foreign Key restraints, but they are not enforced. Which is to say that they are purely informational (for bot the user and the optimizer). A well-formed upsert process in ETL is a good way to manage for this.

On the topic of other issues you may face, here are a few thoughts:

Surrogate Keys Be sure that you generate your surrogate keys either with Netezza's SEQUENCE object, or with a surrogate key generator in your ETL tool. Avoid using ROW_NUMBER for this process as it will most often prevent you from exploiting the parallel nature of the system when used in this way.

Stored Procedures

Stored procedures should avoid row-by-row/cusor-based processing when possible, as this is another case where you may prevent yourself from exploiting the parallel nature of the system.

SQL Extension Functions

If you find that you rely on functions that exists in DB2 that you don't find natively in Netezza, be sure to check what is available in the SQL Extensions Toolkit, which is included with Netezza, but not automatically installed/configured.

MERGE

If you rely on MERGE in your current environment, be aware that you must be on v7.2.1 to use MERGE in Netezza. Otherwise you will have to break it out into an INSERT/UPDATE operation.

Answer 2

Once you load the data in Netezza, one method we have utilized is to create a View to access the data and only expose the view. The view would have the logic inside to remove the duplicates.

Good luck! Delan