IBM has just announced they are waving all rights and providing access to 500
patents. In the list of 500 there are several that relate RDBMS and query
optimizations, it may be worth a look.
http://www.ibm.com/news/us/en/2005/01/patents.html
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Darcy Buskermolen
Wavefire Technologies Corp.
ph: 250.717.0200
fx: 250.763.1759
http://www.wavefire.com