Explain and write the pseudocode for a Mapper/Reducer that takes as input a larg

Question

Explain and write the pseudocode for a Mapper/Reducer that takes as input a large file (possibly split into chucks) of integers and outputs:

a. The sum of the squares of each integer

b. The maximum integer

c. Assume you have a database with two relations (i.e. tables): customers and accounts.

The schema for customers is composed of the following attributes:

• customerID (integer)

• name (string)

• address (string)

• phone (string)

The schema for accounts is composed of the following attributes:

• customerID (integer)

• accountNumber (integer)

• balance (float)

Write the following queries using SQL:

A. Find the customer name with account number 12345.

B. Find all customer names who have at least one account with balance >$100,000 Write the following queries using Relational Algebra:

C. Find all account numbers with balance <$20,000 D. Calculate the sum of all accounts for customer with ID=432

Explanation / Answer

A)Select A.name from customers A join accounts B on A.customerID=B.customerID where B.accountNumber=12345

B)Select A.name from customers A join accounts B on A.customerID=B.customerID where B.balance>100000

C)Select accountNumber from accounts where balance<20000

D)Select Count(*) from accounts Where customerID=432

Note: In Question D, we are not clear about the requirement. Is it total no of accounts with id = 432 or sum of the balance of all accounts with id = 432.

If it is the sum of the balance of all accounts with id = 432, then take the below query.

Select Sum(balance) from accounts where customerID=432 Groupby customerID

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