# chord distributed hash table

## Can distributed hash table?

A distributed hash table (DHT) is a distributed system that provides a lookup service similar to a hash table : key-value pairs are stored in a DHT, and any participating node can efficiently retrieve the value associated with a given key.

## What is chord in distributed system?

In computing , Chord is a protocol and algorithm for a peer-to-peer distributed hash table. A distributed hash table stores key-value pairs by assigning keys to different computers (known as “nodes”); a node will store the values for all the keys for which it is responsible.

## What is a finger table?

Finger Table . Finger table is a routing table used in chord to accelerate the lookup process. each and every node maintain finger table with m entries(when the circle is from 0 to 2^(m-1)).

## Why do we need consistent hashing?

Consistent hashing solves the problem of rehashing by providing a distribution scheme which does not directly depend on the number of servers. To find out which server to ask for a given key or store a given key, we need to first locate the key on the circle and move in a clockwise direction until we find a server.

## What is hash table and hash function?

In computing, a hash table ( hash map) is a data structure that implements an associative array abstract data type, a structure that can map keys to values. A hash table uses a hash function to compute an index, also called a hash code, into an array of buckets or slots, from which the desired value can be found.

## What is DHT nodes in utorrent?

With trackerless/ DHT torrents, peer IP addresses are stored in the DHT using the BitTorrent infohash as the key. In a DHT , peers are randomly assigned to store values belonging to a small fraction of the key space; the hashing ensures that keys are distributed randomly across participating peers.

## Is hashing repeatable?

Hashing Algorithms A hash is supposed to be repeatable , that means each time we apply it to the same data we should get the same hash value out. This requires that we create a hashing algorithm or function: Use the Hashing Key, apply the hashing algorithm and calculate the hashing value.

## Where is consistent hashing used?

In a distributed system, consistent hashing helps in solving the following scenarios: To provide elastic scaling (a term used to describe dynamic adding/removing of servers based on usage load) for cache servers. Scale out a set of storage nodes like NoSQL databases.

## What is consistent hashing and where is it used?

Consistent Hashing is a distributed hashing scheme that operates independently of the number of servers or objects in a distributed hash table by assigning them a position on an abstract circle, or hash ring. This allows servers and objects to scale without affecting the overall system.