Hash collision

Hash collisions can be unavoidable depending on the number of objects in a set and whether or not the bit string they are mapped to is long enough in length.

[4] Another reason hash collisions are likely at some point in time stems from the idea of the birthday paradox in mathematics.

[9] In practice, security-related applications use cryptographic hash algorithms, which are designed to be long enough for random matches to be unlikely, fast enough that they can be used anywhere, and safe enough that it would be extremely hard to find collisions.

The cache-conscious collision resolution is another strategy that has been discussed in the past for string hash tables.

Cells in the hash table are assigned one of three states in this method – occupied, empty, or deleted.

If a hash collision occurs, the table will be probed to move the record to an alternate cell that is stated as empty.

There are different types of probing that take place when a hash collision happens and this method is implemented.

John Smith and Sandra Dee share the same hash value of 02, causing a hash collision.
John Smith and Sandra Dee are both being directed to the same cell. Open addressing will cause the hash table to redirect Sandra Dee to another cell.