Let's remember the CAP theorem
The CAP theorem is a theorem that describes the nature of blockchain.
The CAP theorem states that it is impossible to satisfy the three properties of "Consistency," "Availability," and "Partition-tolerance" at the same time when operating a web service.
Consistency
Service users can always access the latest data.
Availability
The service does not stop due to a system failure, that is, there is no single point of failure in the system.
Partition-tolerance
The service will not stop even if the system's network is interrupted.
This theorem shows that there is no such thing as a perfect system, and that if you choose something, you have to give up something.
Check your achievement
Click the “Tick” button
if you understand the lesson so far.
CAP Theorem in Blockchain
Now let's apply the CAP theorem to blockchain.
A blockchain is made up of countless nodes, all of which hold exactly the same information.
This means that there is no single point of failure in the system.
Also, the fact that it has zero downtime shows that blockchains excel in "Availability".
We also learned that blockchain communication is Peer-to-Peer.
This means that even if one part of the network is blocked, communication is still possible.
Therefore, we can see that it also has the property of partition-tolerance.
What about Consistency?
Blockchains were built on a PtoP-type communication method with countless nodes.
Therefore, it actually takes a little bit of time for the same data to be propagated to all nodes.
In short, the data held by one node does not match the data held by another node in real time.
This does not have the Consistency property of always having access to the latest data.
Check your achievement
Click the “Tick” button
if you understand the lesson so far.
Understanding the suitability of blockchain
In addition to the properties of blockchains as revealed by the CAP theorem, let's consider the characteristics of "Trustless" and "Transparency" learned in Lesson 2 to understand what blockchains are not suited for.
What blockchain is suited for
Blockchain is suitable for recording data that cannot be tampered with.
Examples include ownership of real estate and securities, and college graduation records.
All of this data can be made public, and by having countless nodes hold the same data, there is no need to worry about it being illegally rewritten.
What blockchain is not suited for
Blockchain is not suitable for recording data that requires immediacy.
As we have seen in the CAP theorem, blockchains are inconsistent in some aspects of data.
Of course, there is a possibility that blockchain will be developed in the future, but blockchain is actually not suitable for payments.
Since payments need to be finalized on the spot in exchange for goods, blockchains, which take a little time to get the payment data across to all nodes, are not very suitable.
On the other hand, in situations where a little time is not a problem, such as overseas remittances, there are many advantages to using blockchain.
Since blockchain started with Bitcoin, it is often misunderstood as a technology for finance, but there are many examples of its use in fields other than finance.
Also, blockchain is not suitable for recording data that can't be viewed.
As we have learned many times, all data recorded in a blockchain is public.
Therefore, you should never record data that you do not want to be viewed, such as personal information.
When considering the practical application of blockchain, this perspective of "what to record in the blockchain" is very important.
Check your achievement
Click the “Tick” button
if you understand the lesson so far.