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nag9sri_139755 avatar image
nag9sri_139755 asked ·

Why is Cassandra a ring architecture?

As the question says , Why Cassandra chose ring architecture , is this to "identify" clear neighbors for each node ?

cassandra
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Russell Spitzer avatar image
Russell Spitzer answered ·

The nodes are not literally on a ring. The ring is a representation of the hashing function output. It is circular because ranges are allowed to span the max value point and carry around to the min value.

Every node claims sections of the ring as the key values that they will own. For more information look up information on tokens and vnodes. Actual node assignment and replica placement is only accomplished with additional data. If vnodes aren't used each node only would one a single continuous section but most deployments use vnodes now.

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