Jio O&M Engineer Interview Questions and Answers

Q1. What are indexes in the database? what is the difference between clustered and non-clustered indexes?
Ans. 
Indexes are used to improve database performance. Clustered indexes determine the physical order of data, while non-clustered indexes do not.
• Indexes are used to speed up data retrieval operations in a database.

• Clustered indexes determine the physical order of data in a table, while non-clustered indexes do not.

• A table can have only one clustered index, but multiple non-clustered indexes.

• Clustered indexes are generally ...read more
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Q2. Write a query to delete duplicate rows from a table.
Ans. 
Query to delete duplicate rows from a table
• Use GROUP BY clause to group the rows by their unique values

• Use HAVING clause to filter out the groups with count greater than 1

• Use DELETE statement to delete the duplicate rows
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Q3. Class A { public string A() { return "hello"; } } what is wrong with above code?
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Q4. What is a singleton pattern and how to implement it?
Ans. 
Singleton pattern restricts the instantiation of a class to a single instance and provides a global point of access to it.
• Create a private constructor to restrict instantiation of the class

• Create a private static instance of the class

• Create a public static method to access the instance

• Ensure thread safety if necessary

• Examples: Database connection, Logger, Configuration settings
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Q5. How do you handle exceptions in stored procedures?
Ans. 
Handle exceptions in stored procedures by using TRY-CATCH blocks.
• Use TRY-CATCH blocks to catch and handle exceptions

• Log the error message and severity level

• Rollback the transaction if necessary

• Rethrow the error if it cannot be handled

• Use RAISERROR to raise custom error messages
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Q6. Explain SOLID principles.
Ans. 
SOLID principles are a set of five design principles that help in creating maintainable and scalable software.
• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open-Closed Principle: Software entities should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Subtypes should be substitutable for their base types.

• I - Interface Segregation Principle: C...read more
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Q7. Difference between throw and throw exception?
Ans. 
throw is used to throw an exception while throw exception is used to throw a specific exception.
• throw is used to throw any type of exception while throw exception is used to throw a specific type of exception.

• throw exception is followed by the type of exception that needs to be thrown.

• throw can be used to throw any object while throw exception can only be used to throw an exception object.

• Example: throw new Exception("
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Q1. Accumulators in spark python sum of odd places in list Partition and bucketing
Ans. 
Spark accumulators are used to accumulate values across multiple tasks in a distributed manner.
• Accumulators are used to accumulate values across multiple tasks in a distributed manner

• They are used to implement counters and sums in Spark

• Accumulators are read-only variables that can only be updated by an associative and commutative operation

• Partitioning is the process of dividing a large dataset into smaller, more manage...read more
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Q1. SQL median query in spark Python user defined exceptions Dataframe - RDD & RDD - Dataframe conversion
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Q1. Reason for change Things to look forward in your next company
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Round duration - 60 minutes
Round difficulty - Medium

Q1. Sum Between Zeroes
You are given a Singly Linked List which contains a series of integers separated by ‘0’.
Between two zeroes, you have to merge all the nodes lying between them into a single node which...read more
Ans. Two Pointer Approach
Let us initialize two pointers, newHead and newTail, with NULL (These will be the head and tail of the final list). Now traverse the given list. Ignore the first zero. Now, as you encounter non-zero nodes, add their values in a variable called ‘sum’. As soon as you encounter a node with data 0, change that node's value to ‘sum’, and
1. If newHead is NULL, this node becomes the new head and tail of the l...read more
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Q2. Minimum Cost to Buy Oranges
You are given a bag of size 'W' kg and provided with the costs of packets with different weights of oranges as a list/array with the name 'cost'. Every i-th posi...read more
Ans. Recursive Approach
Write a recursive function minCostToBuyOrangesHelper(idx, requiredWeight, n) to return the Minimum cost to buy exactly requiredWeight Kg oranges with (idx+1) Kg to N kg packets.
1. Our minimum cost for weight W will be : minCostToBuyOrangesHelper(idx, W, n)
2. Now at any instant (idx, requiredWeight, n), we have two options:
   1. The option of taking this packet:
cost[idx] + minCostToBuyOrangesHelper(idx, requiredWe...read more
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Round duration - 60 minutes
Round difficulty - Medium

Q1. Connect N Ropes With Minimum Cost
You have been given 'N' ropes of different lengths, we need to connect these ropes into one rope. The cost to connect two ropes is equal to sum of their lengths. W...read more
Ans. Brute Force Approach
Clearly, the rope which is picked up first will be having its length included more than once in the final cost. If we pick a rope of larger length earlier, then we will be adding some extra cost to our final result.
So, the idea is to pick ropes of smaller lengths initially to minimize the impact on our final cost.
So, each time we will be finding two smallest ropes, connecting them and
adding the resu...read more
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Q2. DBMS Question
Tell the ACID properties in DBMS.
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