Hashing
A hashing algorithm is a non reversible operation that takes in a string and converts it to a new value which can not be turned back. The output of a hashing algorithm is unique.
Key terms
- Hash collision: When two different strings produce the same hash.
- Hash function: A function that takes in a string and converts it to a hash.
- Hash table: A data structure that uses hashing to store data.
Hash table
A hash table is a method of storing items in a way that makes it easier to find them.
Example
| ID | Name | Age | Hash (from name) |
|---|---|---|---|
| 1 | James | 20 | 3563 |
| 2 | John | 21 | 4536 |
| 3 | Bill | 22 | 6875 |
In this example lets fetch the data for John. We can convert the name John to a hash and then search for that hash in the hash table. This is much faster than searching through the whole table.
Examples of hash functions
- MD5
- SHA-1
- SHA-256
- SHA-512