Are you using forbidden features in Express-C?

developerWorks article: Compare the distributed DB2 9 data servers

If you've spent much time playing with DB2 Express-C, you may have noticed it contains some very powerful features:

• multi-dimensional clustering (MDC)


• materialized query tables (MQTs)


• deep compression


• compressed backups

Technically, Express-C users have no permission from IBM to use the features listed above, even though the product currently doesn't prevent anyone from doing so. IBM generally doesn't disable advanced features on lower-end editions of a shared codebase, and Express-C is no exception, so it's up to the user to understand what is and isn't compliant. Each feature listed above requires a licensed DB2 product edition and one or more add-on packages in order to be legit to use. If IBM suddenly decided to follow through on their rules and disable those features in Express-C, you'd be in a pretty bad spot if your app relied on them, unless you were ready to spend a significant amount of money on emergency upgrades.

If any of this comes as a shock, you'll appreciate the lovingly arranged table of features and products assembled by DB2 maven Paul Zikopoulos. Read it, and your excuses of DB2 licensing ignorance will magically disappear.

By the way, none of this applies to pureXML, which IBM has fully authorized for use in DB2 Express-C, so feel free to use the heck out of that until the neighbors come over and ask you to stop.

Stern, commanding photo courtesy of Michael M. Rubino