PART1

written homework代写
written homework代写

written homework代写 This is a written homework. You should submit the answers to the questions in PDF format including any text and diagrams.

This is a written homework. You should submit the answers to the questions in PDF format including any text and diagrams. There are 5 questions and each question is worth 2 points.

Question 1: Disks written homework代写

RAID 50/RAID 5+0 is a version of nested raid that combines RAID 5 and RAID 0.

  1. Draw a diagram depicting a RAID 50 configuration.
  2. What are 3 advantages and 3 disadvantages of RAID 50 relative RAID 0 and RAID 5. Give a one or two sentence explanation of the reason underlying the advantage, e.g. why does one have better bandwidth than another?written homework代写

Question 2: Fixed and Variable Records

The following statement defines a table.

CREATE TABLE `products` (
  `product_id` char(8) NOT NULL,
  `product_name` varchar(16) NOT NULL,
  `product_description` char(8) NOT NULL,
  `product_brand` enum(‘IBM’,‘HP’,‘Acer’,‘Lenovo’,‘Some really long brand name’NOT NULL,
  PRIMARY KEY (`product_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Give a two or three sentence explanation for why the DBMS would choose a fixed format instead of a variable format, and the reasons.

Question 3: Replacement Policy

Assume that the database block address space has 10 blocks, numbered from 0,1, …, 9. Assume that there are 5 frames in the buffer pool. If the replacement policy is least recently used, the buffer pool is initially empty, and there is a sequence of reads for blocks of the form 0,1,2,3,4,9,4,8,2,6,1 shows the final status of the blocks in the buffer pool.

Do the same for a replacement policy of most recently used, i.e. the block replaced was the last one updated. How many IOs does MRU have compared to LRU.

Question 4: Indexes

Using the table from question 2, assume that the database administrator created an index on product_name. Also assume that queries of the form

SELECT * FROM products WHERE product_name LIKE (“abc%”), with a,b,c being arbitrary characters input by the person submitting the query.

Would you use a Hash or B-Tree index for product_name and why?

Question 5: Query Processing Algorithms

Give a 5 sentence explanation for each of the following:

  1. Nested Loop Join written homework代写
  2. Two-Pass Join Algorithm based on sorting.
  3. Index-Based Join Algorithms.

Simple, succinct is fine just to demonstrate you have read section 15.2-15.6 of Garcia-Molina et al. or equivalent chapters in other books/online sources.

PART 2

Given a table with a set of words with 3 rows, for example the table below, write a query (or script of queries) that produces a table that is the Power Set of the set of words. The query or script:

Must work for any table with the same format at the example, specifically

  1. One column of type VARCHAR
  2. 3 rows with non NULL values.
Word
whale
mouse
fence


For the table above, the Power Set would be of the form

NULL NULL NULL
whale NULL NULL
mouse NULL NULL
fence NULL NULL
whale mouse null
whale fence null
mouse fence null
whale mouse fence

Submission:

  • On CourseWorks
  • A single PDF file. You can use some editor to print or save the content, e.g. DDL, DML, to PDF.
  • DDL for test table and data.
  • DDL and result data for power set table.
  • Execution screen snapshot.
written homework代写
written homework代写

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