这是一篇美国的python数据库+简答python代写
Instructions
- The homework submission date/time is 2022-MAY-01 at 11:59 PM.
- Submission format is a PDF version of this document with your answers. Place your answers in the document after the questions.
- The name of your PDF must be <UNI>_S22_W4111_HW4a_Written.pdf. For example, mine would be dff9_S22_W4111_HW3a_Written.pdf
- You must use the Gradescope functions to mark the location of your questions/answers in the submitted PDF. Failure to mark pages will cause point deductions.Please, please read the countless Ed posts, TA produced instructions and videos, etc. to prepare your submission.
- You can use online sources but you must cite your sources. You may not cut and paste text.
- Questions typically require less than five sentences for an answer. You will lose points if your answer runs on and wanders.
- “Verbosity wastes a portion of the reader’s or listener’s life.”
Questions
Question 1: Explain why a sparse index must also be a clustering index.
Question 2: Briefly explain sparse, multi-level indexes and their benefits. Why can the outer index be sparse?
Question 3: Indexes can significantly improve performance? What are some disadvantages of having many indexes?
Question 4: Briefly compare the pros and cons of B+-Tree versus a Hash Index.
Question 5: Briefly explain the concepts of covering index/covered query.
Question 6: Briefly explain the three main steps/stages in query processing.
Question 8: Explain the role of equivalent queries in query optimization.
Question 9: Assume that the ON clause in a JOIN on tables A and B compares columns a1 with b1 and column a2 with b2. What two properties must the ON condition have for the optimizer to be able to use a Hash Join?