Let's face it - the really really bad performance issues are usually not due some weired database bugs. Instead a wrong system setup or the bad usage of the database prevents a high performance.
Cary Millsap, a very well-known and respected database performance expert, released a very nice little (18 pages) PDF called "For Developers: Making Friends with the Oracle Database".
You can find the link to it on Carys weblog.
Having seen many anti-pattern brought into production systems by so called database-agnostic developers, I really recommend this paper to everybody how needs to use SQL in their applications.
best regards
Lars
