Quantzig Interview Questions and Answers

Coalesce is a function used to return the first non-null value in a list of expressions.

• Coalesce function is commonly used in SQL to handle null values.

• It takes multiple arguments and returns the first non-null value.

• Example: COALESCE(column1, column2, 'default') will return the value of column1 if not null, else column2, and if both are null, it will return 'default'.

Repartition is the process of redistributing data across partitions in a distributed system.

• Repartitioning helps in balancing the workload and improving performance in distributed computing environments.

• It involves moving data between partitions based on certain criteria such as key values or hash functions.

• Repartitioning can be done in Spark using operations like repartition() or coalesce().

A non repeatable character is a character that appears only once in a given string.

• Iterate through the string and count the frequency of each character

• Identify the characters that have a frequency of 1

• Return the first non repeatable character found

Sort list without using sort method

• Create a custom sorting function using loops

• Compare each element with every other element to determine the correct order

• Swap elements based on the comparison results