Original address: http://tech.ifeng.com/a/20180217/44881925_0.shtml
The concept of blockchain (blockchain) is becoming popular due to the prosperity of virtual currencies such as Bitcoin. In fact, this technology can also be applied to many other fields because of special design ideas. As a distributed data storage mode with high fault tolerance, what are the differences between blockchain and traditional databases? To answer this question, we need to look at how they work.
Distributed nodes of the blockchain.
traditional database
Traditional databases use a client-server network architecture. In this structure, users (or clients) can modify data stored in a central server. Control of the database remains with designated authorities, who authenticate users before attempting to access the database. Since the authority is responsible for the management of the database, if the security of the authority is compromised, the data is at risk of being modified or even deleted.
Blockchain database
The blockchain database consists of several decentralized nodes. Every node will participate in data management: all nodes will verify the content newly added to the blockchain and write the new data to the database. For new content to be added to the blockchain, a majority of nodes must agree to write successfully. This consensus mechanism ensures network security and makes it very difficult to tamper with content.
The most interesting example of blockchain is Bitcoin, in which consensus is achieved through "mining" (using computers to calculate solutions to complex hashing problems); and in another well-known case, Ethereum , the consensus mechanism is done by proof of stake (POS).
Integrity and Transparency
A major feature of blockchain technology that differentiates it from traditional database technology is its public verifiability, which is achieved through integrity and transparency.
Integrity: Every user can be assured that the data they retrieve has not been corrupted or overwritten since the moment it was recorded.
Transparency: Every user can be informed and verified how the content of the blockchain has changed over time.
CRUD vs read & write operations
In a traditional database , customers can perform four operations on data: create, read, update, and delete (commonly known as CRUD commands).
And blockchain can only increase. Users can only add data in additional blocks, all previous data is stored permanently and cannot be changed. Therefore, the blockchain can only do the following:
Read: query and obtain data with the blockchain;
Write: Add more data to the blockchain.
verify and write
The blockchain has these two functions: transaction verification and new transaction writing. A transaction is an operation that changes the state of data on the blockchain. The previous entries on the blockchain remain unchanged forever, and new entries can change the state of the data in the previous entries. For example, if the blockchain records that I have a million bitcoins in my bitcoin wallet, that number is permanently stored in the blockchain. When I spend 200,000 bitcoins, the transaction is also recorded on the blockchain, and my balance is 800,000 bitcoins. However, since the blockchain can only continue to grow, the balance of 1 million bitcoins before this transaction is still permanently stored on the blockchain. This is why blockchain often refers to an immutable distributed ledger.
In conclusion, the difference is in decentralized control
Decentralized control removes the risk of centralized control. Anyone with sufficient access to a centralized database can destroy or destroy the data in it, so users rely on the database administrator's security infrastructure.
Blockchain technology circumvents this problem by using decentralized data storage to build security into its own structure.
Blockchain technology is very suitable for recording certain kinds of information, while traditional databases are more suitable for recording other kinds of information. It is critical for each organization to understand what it wants from a database, and we need to judge the strengths and weaknesses of each before choosing a database.