Block chain overall structure diagram
blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies. Blockchain is an important concept of bitcoin,
in essence, it is a decentralized database. At the same time, as the underlying technology of bitcoin, it is a series of data blocks generated by using cryptographic methods. Each data block contains a batch of information of bitcoin network transactions, Used to verify the validity of its information (anti-counterfeiting) and generate the next block
extended data
most blockchain public chains are limited by scalability. The biggest feature of blockchain technology is decentralization, which requires that all accounts in the network need to deal with the accounting process. Distributed accounting has high security, low misoperation rate, political neutrality and correctness
however, blockchain technology embraces these features at the same time, sacrificing scalability, unable to meet the personalized supervision, and slightly insufficient in protecting data privacy. Moreover, with the increase of the number of ledger, the interaction delay will increase exponentially, that is to say, the more ledger in the blockchain network, the higher the delay
MACD is called the moving average of similarities and differences, which is developed from the double index moving average. The fast line dif is obtained by subtracting the slow index moving average (ema26) from the fast index moving average (ema12), and then 2 × Fast line dif-dif's 9-day weighted moving average (DEA) obtained MACD column. The significance of MACD is basically the same as that of double moving average, that is, the dispersion and aggregation of fast and slow moving average represent the current long short state and the possible development trend of stock price, but it is more convenient to read. When MACD turns from negative to positive, it's a buy signal. When MACD turns from positive to negative, it's a sell signal. When MACD changes from a large angle, it means that the gap between the fast moving average and the slow moving average widens very quickly, which represents the change of a market trend.
From the perspective of technology and architecture, I will tell you my understanding of blockchain in common language
what is blockchain? In a word, blockchain is a storage system. To be more specific, blockchain is a distributed storage system without an administrator and each node has all the data
What are the common storage systems like
first, how to ensure high availability
the common storage system usually uses "rendancy" to solve the problem of high availability. As shown in the figure above, if the data can be copied into several copies and rendant to multiple places, high availability can be guaranteed. The data in one place is hung, and there is data in other places. For example, the master-slave cluster of MySQL is the same principle, and the raid of disk is also the same principle
two points need to be emphasized in this place are: data rendancy often leads to consistency problems
1. For example, in the master-slave cluster of MySQL, there is actually a delay in reading and writing, which means there is a inconsistency in reading and writing in a short period of time. This is a side effect of data rendancy
The second point is that data rendancy often reces the efficiency of writing, because data synchronization also consumes resources. If you add two slave libraries, the write efficiency will be affected. The common storage system is to use rendancy to ensure the high availability of dataso the second question, ordinary storage system, can write more
the answer is yes, for example, take this graph as an example:
in fact, MySQL can do a master-slave synchronization of al masters, master-slave synchronization of al masters, two nodes can be written at the same time. If you want to do a multi room multi live data center, in fact, multi room multi live data synchronization. What we should emphasize here is that multi-point writing often leads to the consistency problem of writing conflicts. Take MySQL as an example, suppose that the attribute of a table is self incrementing ID, then the data in the database is 1234 now. If one of the nodes writes and inserts a piece of data, it may become 5, and then these 5 pieces of data are synchronized to another master node, Before synchronization, if another write node inserts a piece of data, a piece of data with self incrementing ID of 5 will be generated. Then, after the generation, synchronize to another node, and the synchronized data will conflict with the two local 5's after it arrives, which will lead to synchronization failure and write consistency conflict. This problem will occur in the case of multi-point writing
how to ensure consistency in multi-point writing
the reform "Swan class" gives you more technical work
A: the basic characteristics of blockchain
I. decentralization
blockchain technology does not rely on additional third-party management institutions or hardware facilities, and there is no central control. In addition to the self-contained blockchain itself, each node realizes information self verification, transmission and management through distributed accounting and storage
the foundation of blockchain technology is open source. In addition to the private information of all parties involved in the transaction is encrypted, the data of blockchain is open to everyone. Anyone can query blockchain data and develop related applications through the open interface, so the information of the whole system is highly transparent
Third, independencebased on consensus specifications and Protocols (similar to various mathematical algorithms such as hash algorithm used by bitcoin), the whole blockchain system does not rely on other third parties, and all nodes can automatically and safely verify and exchange data in the system without any human intervention
Four, safetyas long as 51% of all data nodes cannot be controlled, the network data cannot be arbitrarily controlled and modified, which makes the blockchain itself relatively safe and avoids subjective and artificial data changes
5. Anonymityunless there are legal requirements, technically speaking, the identity information of each block node does not need to be disclosed or verified, and the information transmission can be anonymous