database

数据库作业代写 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

PART1： 数据库作业代写

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

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?数据库作业代写

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.数据库作业代写

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.数据库作业代写

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.数据库作业代写

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
2. Two-Pass Join Algorithm based on sorting. 数据库作业代写
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 数据库作业代写

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

Submission: 数据库作业代写

• 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.