Big Data Consultant Interview Questions and Answers

The 'exists' operator is used to check for the existence of a field in a document, while the 'in' operator is used to match a field against a list of values.

• The 'exists' operator is used in MongoDB to check if a field exists in a document.

• The 'in' operator is used in SQL to match a field against a list of values.

• Example: 'exists' operator - db.collection.find({ field: { $exists: true } })

• Example: 'in' operator - SELECT * FROM table WHERE field IN (value1, value2, value3)

An index is a data structure that improves the speed of data retrieval operations in a database.

• Indexes are used to quickly locate data without having to search every row in a database table.

• Types of indexes include clustered indexes, non-clustered indexes, unique indexes, and composite indexes.

• For example, a clustered index physically reorders the data in the table based on the index key, while a non-clustered index creates a separate structure to store the index key values ...read more

Use SQL query with ORDER BY and LIMIT to find 6th highest salary.

• Use ORDER BY clause to sort salaries in descending order

• Use LIMIT 1 OFFSET 5 to get the 6th highest salary

A server is a computer or software program that provides functionality for other programs or devices, often over a network.

• A server stores and manages data, files, or applications that can be accessed by clients over a network.

• Servers can provide services such as email, web hosting, file storage, and database management.

• Examples of servers include web servers like Apache, email servers like Microsoft Exchange, and file servers like Windows Server.