Modulus Hash Function#
Modulus hashing, also known as division hashing, is a simple and efficient technique for mapping data to a fixed-size range. It utilizes the modulo operation (denoted by %) to achieve this mapping.
Here’s how it works:
Input: You have a piece of data like a number, a string, or any other information you want to map to a specific range.
Hash Function: The hash function in modulus hashing simply uses the modulo operation with a pre-defined modulus value (often denoted by
m). The modulus value determines the size of the output range.Output: The output is the remainder obtained when the data is divided by the modulus value. This remainder becomes the hash value, representing the data in the desired range (from 0 to
m-1).
Example:
Let’s say you want to map the number 23 to a range of 0 to 4 (using a modulus value of
m = 5).Applying the modulo operation:
23 % 5 = 3.Therefore, the hash value for 23 in this case is 3.
Benefits of Modulus Hashing:
Simplicity: It is a very basic and easy-to-implement technique for generating hash values.
Efficiency: The modulo operation is usually a fast and efficient operation, making it suitable for situations where speed is crucial.
Limitations of Modulus Hashing:
Collision Prone: While simple, modulus hashing is susceptible to collisions. This occurs when different data points map to the same hash value. Collisions can lead to issues like incorrect data retrieval or insertion in hash tables.
Limited Distribution: The distribution of hash values highly depends on the chosen modulus value. A poorly chosen modulus can lead to uneven distribution, where some parts of the range receive more data than others, impacting efficiency.
Applications of Modulus Hashing:
Hash Tables: While not ideal due to collision concerns, modulus hashing can be used in simple hash tables, especially when dealing with small datasets and the potential for collisions is low.
Load Balancing: It can be used in basic load balancing schemes to distribute tasks or requests across multiple servers by mapping them to a specific server based on the calculated hash value.
However, it’s important to remember that modulus hashing is not considered a cryptographically secure hashing function. It should not be used for security-sensitive applications, like password storage, where collisions can have serious consequences.