Source code analysis of Chang'an chain data storage

summary

The enclosure is responsible for persisting blocks on the storage chain 、 transaction 、 state 、 Historical read / write sets and other ledger data , And provide the query function of the above data . Blockchain conducts batch data submission in blocks , One block submission will involve the submission of multiple ledger data , such as ： Transaction submission , Status data modification, etc , Therefore, the storage module needs to maintain the atomicity of ledger data . Chang'an chain supports common databases to store ledger data , Such as LevelDB、BadgerDB、TikvDB、MySQL Such as the database , The business can choose any database to deploy the blockchain .

The ledger data is mainly divided into 5 class ：

1. Block data , Record block meta information and transaction data ：

   • Block metadata includes ： Block head 、 block DAG、 Trading in the block txid list ,additionalData etc. ;

   • Trading data , That is, the serialized transaction body , To provide query of single transaction data , Therefore, the transaction data is stored separately .

2. Status data , Record the online status data read and written in the smart contract , The state of the world .

3. The historical data , Chang'an chain has a history of state changes during the execution of each transaction 、 Contract call history 、 The transaction history initiated by the account can be recorded , It can be used for subsequent retrospective transactions 、 The transition process of state data .

4. Contract execution result read / write set data , Chang'an chain has separately saved the read and write status data set of each transaction during execution , It is convenient for other nodes to synchronize data quickly .

5. Event data , Event log generated during contract execution

To be improved