25. What is a hash table collision? How can it be prevented?

This is one of the important data analyst interview questions.

The sample answer is…

When two separate keys hash to a common value, a hash table collision occurs. This means that two different data cannot be stored in the same slot.

Hash collisions can be avoided by two methods :

· Separate chaining – In this method, a data structure is used to store multiple items hashing to a common slot.

· Open addressing – This method seeks out empty slots and stores the item in the first empty slot available.