Logo DWBI.org Login / Sign Up
Sign Up
Have Login?
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Login
New Account?
Recovery
Go to Login
By continuing you indicate that you agree to Terms of Service and Privacy Policy of the site.
NoSQL

Understanding CAP theorem

 
Updated on Sep 29, 2020

Despite the high demand in recent years for massively distributed databases with high partition fault-tolerance, the CAP theorem stipulates that it is actually impossible for a distributed system to provide consistency, availability and partition fault-tolerance guarantees simultaneously; a distributed system can satisfy at most any two of these guarantees at the same time, but not all three. Let's understand this in detail.

Understanding the CAP

So what does the 3 letters of CAP actually mean?

Consistency

Concurrently executing queries see the same valid and consistent data at the same time.

Availability

This is a guarantee that every request receives a response about whether it succeeded or failed.

Partition-tolerance

Also known as fault-tolerance, this is a guarantee that the system continues to operate despite arbitrary message loss.

Because no distributed system is capable of satisfying all three guarantees at the same time, a tradeoff must be made. While traditional databases make that decision for us, NoSQL databases provide these guarantees as tuning options. Database vendors must always decide which two to prioritize. The options are as follows:

  • Availability is compromised in favour of consistency and partition-tolerance.
  • Partition-tolerance is forfeited in favour of consistency and availability.
  • Consistency is compromised but systems are always available and can work when parts are partitioned.

Traditional SQL databases place a high priority on consistency and fault-tolerance and have generally as a result chosen to go with the first option above and forfeit high availability. NoSQL databases frequently leave that decision to the application operations team and provide configuration options so that the preferred options can be chosen based on the application use case.

PrimeChess

PrimeChess.org

PrimeChess.org makes elite chess training accessible and affordable for everyone. For the past 6 years, we have offered free chess camps for kids in Singapore and India, and during that time, we also observed many average-rated coaches charging far too much for their services.

To change that, we assembled a team of top-rated coaches including International Masters (IM) or coaches with multiple IM or GM norms, to provide online classes starting from $50 per month (8 classes each month + 4 tournaments)

This affordability is only possible if we get more students. This is why it will be very helpful if you could please pass-on this message to others.

Exclucively For Indian Residents: 
Basic - ₹1500
Intermediate- ₹2000
Advanced - ₹2500

Top 10 Articles