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.
- Draw a diagram depicting a RAID 50 configuration.
- 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:
- Nested Loop Join
- Two-Pass Join Algorithm based on sorting. 数据库作业代写
- 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
- One column of type VARCHAR
- 3 rows with non NULL values.
| Word 数据库作业代写 |
| whale |
| mouse |
| fence 数据库作业代写 |
For the table above, the Power Set would be of the form
| NULL | NULL | NULL |
| whale | NULL 数据库作业代写 | NULL |
| mouse | NULL | NULL |
| fence | NULL | NULL |
| whale | mouse | null |
| whale | fence | null 数据库作业代写 |
| mouse | fence | null |
| whale | mouse | fence |
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.
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