BEST代写-线上留学生作业代写 & 论文代写专家


Python数据库代写|W4111 – Introduction to Databases Sections 002

Python数据库代写|W4111 – Introduction to Databases Sections 002




  • 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.”



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?


Question 10: What is index selectivity? How does it factor into query optimization for JOINs?