DBS: 4.29. Summary

This is the Database Systems II Instructor: Ouldooz Baghban Karimi (https://ouldooz.com) Textbook: Database Management Systems Raghu Ramakrishnan, Johannes Gehrke http://pages.cs.wisc.edu/~dbbook/ Database System Concepts Avi Silberschatz, Henry F. Korth, S. Sudarshan https://www.db-book.com/ Review Questions: (1) How do we use system catalog for query optimization? (LV: 4.24) (2) What is a reduction factor? (LV: 4.23) (3) Why an equidepth histogram may provide the opportunity for better estimates? (LV:4.24) (4) What is an adaptive optimizer? When it is used? (LV: 4.22) (5) When do we use heuristics in cost-based optimization? (LV: 4.25) (6) What is hill climbing? (LV:4.25) (7) What is branch-and-bound enumeration? (LV: 4.25) (8) Why optimizers typically only consider left-deep plans? (LV:4.26) (9) If decorelation is not possible, how the sub-queries in a correlated query will be enumerated? (LV:4.27) (10) Can an operation in a query affect the choice of the algorithm for another operation? How? (LV:4.28)