CAP theorem ?

[BugNoJutsu]

Can you explain the consistency models in distributed databases (e.g., CAP theorem)?

[bouzayenilyes]

CAP Theorem in Distributed Systems

The CAP theorem states that a distributed database can only provide two out of the following three guarantees at the same time:

1. Consistency

Every read returns the most recent write.
This is crucial in distributed systems because data is replicated across multiple servers, and immediate replication is required to ensure consistency.

2. Availability

Every request receives a valid response, regardless of the state of other nodes in the system.

3. Partition Tolerance

The system continues to operate even during partial network failures without losing data.

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Example Scenarios

• Consistency + Availability: The system cannot tolerate network partitions.
• Availability + Partition Tolerance: Immediate consistency is not guaranteed; some reads may return stale data.
• Consistency + Partition Tolerance: The system may not always be available while waiting for data to synchronize.