What is the Difference between Immediate and Eventual Consistency?

Consistency refers to the property that ensures that all data in a system remains accurate and reliable over time. It ensures that when multiple clients or users access the same data, they all see the same, most up-to-date version of that data.

What is Immediate Consistency?

Immediate consistency ensures that updates made to a data store are immediately visible to all clients. This means that once a write operation is completed, any subsequent read operation will reflect the updated value.

• Immediate consistency provides strong consistency guarantees, ensuring that all clients see the most recent data at the same time.
• However, achieving immediate consistency can sometimes result in higher latency for write operations, as the system must ensure that updates are immediately propagated to all clients to maintain consistency.

What is Eventual Consistency?

Eventual consistency means that after you make a change, it might take some time before everyone sees that change. So, for a short while, different people might see different versions of the information.

• Eventually, everyone will see the same updated information. This approach is not as strict as immediate consistency, where everyone has to see the change right away.
• Because of this flexibility, eventual consistency can sometimes make things faster, especially when it comes to making updates.

Differences between Immediate and Eventual Consistency

Below are the differences between Immediate and Eventual consistency:

Aspect	Immediate Consistency	Eventual Consistency
Visibility of Data	Updates are immediately visible to all clients.	Updates may not be immediately visible to all clients.
Consistency Guarantees	Strong consistency guarantees.	Weaker consistency guarantees.
Performance	May incur higher latency for write operations.	Write operations may have lower latency.
Complexity	Can be more complex to implement in distributed systems.	Easier to implement in distributed systems.
Conflict Resolution	Easier to handle conflicts due to strong consistency.	May require conflict resolution mechanisms.
Use Cases	Suitable for applications requiring strong consistency.	Suitable for applications where eventual consistency is acceptable.