Consistent hashing

<p>In <a href="/facts/Computer_science/lN3pEyPz">computer science</a>, consistent hashing is a special kind of <a href="/facts/Hash_function/rk6MlCt3">hashing</a> technique such that when a <a href="/facts/Hash_table/Ht4ptDPF">hash table</a> is resized, only 
  
    
      
        n
        
          /
        
        m
      
    
    {\displaystyle n/m}
  
 keys need to be remapped on average where 
  
    
      
        n
      
    
    {\displaystyle n}
  
 is the number of keys and 
  
    
      
        m
      
    
    {\displaystyle m}
  
 is the number of slots. In contrast, in most traditional hash tables, a change in the number of array slots causes nearly all keys to be remapped because the mapping between the keys and the slots is defined by a <a href="/facts/Modular_arithmetic/0wtRa5dU">modular operation</a>.
</p><p>Consistent hashing evenly distributes cache keys across <a href="/facts/Shard_(database_architecture)/YSE3YS0M">shards</a>, even if some of the shards crash or become unavailable.
</p>

Consistent hashing open-in-new

Consistent hashing