Lesson 4: What is the difference between a blockchain and a distributed database?

Why does this lesson matter?

Now that we have learned the outline of blockchain, some of you who are familiar with IT systems may be wondering, "How is this different from a distributed database? Some of you who are familiar with IT systems may be wondering, "What is the difference between this and a distributed database? The difference between blockchain and distributed databases, a system that has existed for a long time, is often discussed. Through this lesson, let's deepen our understanding of the differences between blockchain and distributed databases.

What you can learn in this lesson

  • About Distributed Databases
  • Differences between blockchain and distributed databases

目次を表示する

What is a distributed database, anyway?

Before touching on the differences between blockchain and distributed databases, let's first learn about databases and distributed databases.

A database is a ledger for recording digital information (data).

When developing web services, we record user information and information about the contents to be provided as a service in a database, and display them according to the user's behavior.

In the case of PoL, the text and illustrations in the lesson you are reading are recorded in the PoL database.

In the case of cryptocurrencies, transaction information is recorded in the blockchain, so we can say that the blockchain is a kind of database.


A distributed database is also a type of database, meaning a database that is geographically distributed.

When operating a web service, information is rarely managed by only one database.

This is because the database may break down due to human failures such as operational errors or disasters such as earthquakes or lightning.

If the database is broken, the information stored in it will be lost and the service will not be able to operate.

This is why information is stored in multiple databases that are geographically dispersed.


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Difference between blockchain and distributed database


There is no corresponding server

The communication method that uses distributed databases is called client-server type.

By client, I mean a web browser or similar device.

In this communication method, a server exists between the web browser and the database, and controls the order of all communication.

In other words, the communication flow is client⇆server⇆database.


On the other hand, the communication method that uses blockchain is called Peer-to-Peer type.

Peer corresponds to the client in the client-server type, and is sometimes referred to as a node.

In this communication method, there is no administrator like a server, and peers (nodes) communicate directly with each other.

Therefore, the order of communication is determined by a consensus algorithm.

In addition, the blockchain itself serves as a database, and the peers also function as a blockchain.

In other words, the communication flow is complete with peer⇆peer⇆peer.


Achieving Zero Downtime

One of the elements that blockchain has made possible is zero downtime.

This is the concept that server downtime is zero, i.e., it never occurs.


As shown in the figure above, servers play a very important role in Internet communication, and if a server goes down, web services cannot be provided temporarily.

Therefore, web service providers spend huge amounts of money to build not only distributed databases, but also load balancing on servers.

By using blockchain, they can not only reduce the huge cost, but also improve the service value through zero downtime.


Increasing the number of units does not improve performance

In the case of distributed databases, the performance of the system can be improved by increasing the number of databases.

On the other hand, in a blockchain, all peers (nodes) hold exactly the same data, so increasing the number of peers will not improve performance.

However, it does increase decentralization, which is important for blockchains to achieve decentralization.


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Blockchain and distributed databases have different purposes

To begin with, distributed databases and blockchains should not be compared because they are used for different purposes.


Distributed database

  • To distribute the load
  • To distribute data in case of disaster
  • Distribute data to speed up processing


Blockchain

  • Decentralize processing authority (to eliminate arbitrariness)
  • Distribute data in order to minimize data tampering
  • Decentralize to reduce time and cost
  • Distribute to trade any value


It is not possible to compare different purposes with the same evaluation axis, and it will be important to consider the advantages and disadvantages of each, and the perspective of using them for different purposes.


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Lesson 4: What is the difference between a blockchain and a distributed database?

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