I had assumed that with the rise of Open Source RDBMS that Open Source RDBMS had a larger share in the Linux platform. I am wrong.
According to the article, IBM, Oracle Tie For No. 1 In Database Market, "Oracle accounted for 80.5 percent of new license sales on the Linux platform". Oracle has been running in Linux for years now. I used to support Oracle on Linux during my days in Oracle Support and that was in my other life.
So, it is not that surprising to me that Oracle would dominate the Linux market. I just assumed that enterprises who use Linux are more open to Open Source Software and would use Open Source RDBMS like MySQL and Postgres.
The other interesting thing I found from the article:
"RDBMS revenues on the Unix platform declined by 0.7 percent, as Linux-based RDBMS sales increased by more than 118 percent. Revenues from new licenses on the open-source operating system, however, remained relatively small at $654.8 million."
The study classified Linux separate from Unix even if Linux is a flavor of Unix.