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`)

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.


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.

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

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


  • 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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