CAP theorem in DBMS Theory - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the CAP theorem stand for in distributed systems?

CAP stands for Consistency, Availability, and Partition tolerance. It explains the trade-offs in distributed databases.

beginner

Define Consistency in the context of the CAP theorem.

Consistency means every read receives the most recent write or an error. All nodes see the same data at the same time.

beginner

What is Availability according to the CAP theorem?

Availability means every request receives a response, without guarantee that it contains the latest write.

beginner

Explain Partition tolerance in simple terms.

Partition tolerance means the system keeps working even if network parts can't talk to each other.

intermediate

Why can't a distributed system have all three: Consistency, Availability, and Partition tolerance at the same time?

Because when network failures happen (partition), the system must choose between being consistent or available, but not both.

Which two properties can a distributed system guarantee simultaneously during a network partition?

A Consistency and Partition tolerance

B All three: Consistency, Availability, and Partition tolerance

C Consistency and Availability

D Availability and Partition tolerance

During a partition, a system can choose to be available and partition tolerant but may lose consistency.

What does Availability guarantee in a distributed system?

A Every request gets a response

B All nodes have the latest data

C System never experiences network failures

D Data is always consistent across nodes

Availability means the system responds to every request, even if data might not be the latest.

Partition tolerance means:

A System stops working during network failures

B System continues working despite network splits

C System always returns consistent data

D System is always available

Partition tolerance means the system keeps functioning even if parts of the network can't communicate.

If a system chooses Availability over Consistency during a partition, what might happen?

A Users see outdated or different data

B System stops responding

C Data is always synchronized

D Network partition is fixed automatically

Choosing availability may cause users to see stale or inconsistent data.

Which of these is NOT a property in the CAP theorem?

A Consistency

B Availability

C Performance

D Partition tolerance

Performance is important but not part of the CAP theorem properties.

Explain the CAP theorem and its significance in distributed system design.

Think about what happens when parts of a network can't communicate.

Describe a real-life example where a system might prioritize Availability over Consistency.

Consider apps where users expect quick responses even if data is slightly outdated.