Stefan Koehler follows his passion about Oracle since more than 21 years and specialized in Oracle performance tuning, especially in Oracle cost based optimizer (CBO) and database internal related topics. Nowadays he primarily works as an independent Oracle database performance consultant and researcher in large mission critical environments for market-leading companies or multi-billion-dollar enterprises in various industries all over the world. He usually supports his clients in understanding and solving complex Oracle performance issues and troubleshooting nontrivial database issues on short-term contracting basis. He is also a proud member of the OakTable Network.