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

This is one of the important data analyst interview questions. 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:

  • 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.