Stefan Koehler follows his passion about Oracle since +13 years and specialized in Oracle performance tuning, especially in Oracle cost based optimizer (CBO) and database internal related topics. Nowadays he primarily works as a freelance Oracle database performance consultant in large mission critical environments (e.g. +10 TB databases) 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.