Which consistency level guarantees that all writes are visible only after successfully being confirmed to all replicas?

Strong consistency guarantees that all writes are visible only after they have been successfully confirmed to all replicas. This means that when a write operation is performed, any subsequent read operations will reflect that write, ensuring a coherent view of the data across the distributed system.

In strong consistency, when an application reads data, it will always receive the most recent committed write. This guarantees that all users see the same data at the same time, which is crucial for scenarios where accurate real-time data representation is essential, such as in financial transactions or operational data.

This level of consistency is crucial in applications where precision and consistency are paramount, but it does come with potential trade-offs in terms of performance and availability, particularly in distributed systems, where confirming writes across multiple replicas can introduce latency. Understanding this concept is vital for designing database systems that require strict consistency.

For other consistency models, they provide varying levels of flexibility or performance but do not guarantee that all writes are immediately visible upon confirmation across all replicas. Eventual consistency, for example, allows for higher performance and availability but does not ensure immediate visibility of writes across the system. Bounded staleness and session consistency offer different trade-offs as well, but they do not meet the strict criteria of strong consistency.