Grokking the System Design Interview, Volume II
Vote

0% completed

​

Cassandra Consistency Levels

Let's explore how Cassandra manages data consistency.

What are Cassandra's consistency levels?

Cassandra's consistency level is defined as the minimum number of Cassandra nodes that must fulfill a read or write operation before the operation can be considered successful. Cassandra allows us to specify different consistency levels for read and write operations. Also, Cassandra has tunable consistency, i.e., we can increase or decrease the consistency levels for each request.

There is always a tradeoff between consistency and performance

.....

.....

.....

Like the course? Get enrolled and start learning!
A

Amey Naik

· 5 years ago

"Cassandra selects a single replica to query for the full object and asks for the digest of the data from two additional nodes in order to ensure that the latest version of the data is returned. The Snitch helps to identify the fastest replica, and Cassandra asks this replica for the full object."

Show 2 replies
T

Techies

· 3 years ago

Please explain

To achieve strong consistency in Cassandra: Read Replica Count +Write Replica Count> Replication Factor gives us strong consistency. In this equation. All client reads will see the most recent write in this scenario, and we will have strong consistency.

Q1: How is Read/Write Replica Count different than Replication Factor count?

Q2: Example: A cluster has a total of 3 nodes, Read replica 1, Write Replica 1, Replication factor 1. But still its possible that one node may not have the latest data, so how will it be strongly consistent?

Show 1 reply