What are some examples of consistency in distributed systems?

What are some examples of consistency in distributed systems?

In distributed systems, consistency ensures that all nodes see the same data at the same time. Examples include: 1. Strong Consistency: Systems like Google Spanner use a consensus algorithm to ensure all nodes reflect the same state. 2. Eventual Consistency: Amazon DynamoDB allows for temporary inconsistencies but guarantees that all updates will propagate eventually. 3. Causal Consistency: Systems like Apache Cassandra ensure that operations that are causally related are seen by all nodes in the same order.

Can you explain strong consistency in more detail?

Sure! Strong consistency means that once a write is acknowledged, all subsequent reads will reflect that write. This is often achieved through consensus protocols like Paxos or Raft, which ensure that all nodes agree on the order of operations before they are applied.

What are the trade-offs of using eventual consistency?

Eventual consistency allows for higher availability and partition tolerance, but it can lead to temporary inconsistencies. This means that different nodes might return different values for a short period, which can be problematic for applications requiring immediate accuracy.

How does causal consistency differ from strong consistency?

Causal consistency allows operations that are causally related to be seen in the same order by all nodes, but it doesn't require all operations to be seen in the same order. In contrast, strong consistency requires that all operations are seen in the exact order they were applied, which can limit performance and availability.