Database Modeling and Design, 5th Edition

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Query Optimization and Plan Selection

It is a capital mistake to theorize before one has the data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.

—Sir Arthur Conan Doyle (1859–1930)

If you ever wanted to learn to play the piano, there are many different approaches that people have tried over the past three centuries. The traditional recommended way is to sign up with a professional teacher and take lessons one-on-one. Others have tried a variety of methods of self-instruction, such as using books like Piano for Dummies, watching videos, or just getting some sheet music and starting to play. Regardless of which method you choose, there is another variable, namely how to proceed to learn the piece you ...