Orientdb database transaction processing and concurrent control

Orientdb database transaction processing and concurrent control 【Introduction】 OrientDB is a high -performance, multi -model open source database management system with strong transaction processing and concurrent control capabilities.This article will introduce the transaction processing and concurrent control mechanism of the OrientDB database, and provide relevant programming code and configuration description to help readers better understand and use these functions. 【Affairs processing】 Affairs is a logical unit for database operations. It is used to ensure that a series of database operations are either successfully executed or all fails.OrientDB provides atomic, consistency, isolation and persistence. Programming code example: ODatabaseSession db = orientDB.open("mydatabase", "admin", "admin"); ODatabaseTransaction tx = db.getTransaction(); try { tx.begin(); // Execute a series of database operations tx.commit(); } catch (Exception e) { tx.rollback(); } finally { tx.close(); db.close(); } The above code shows a basic transaction processing process.First open the database connection through the `Open` method, and use the designated user name and password to verify.Then obtain the current session's transaction object through the `Gettransaction` method.Perform the database operation between the `Begin` method and the` Commit` method. If an exception occurs, roll the transaction through the `Rollback` method.Finally, use the `Close` method to close the transaction and database connection. 【Parallel control】 Concurrent control is used to handle the execution and conflict of multiple concurrent transactions to ensure the integrity and consistency of the database.OrientDB supports multi -size concurrent control, including locking mechanism and MVCC (multi -version concurrent control). -Locking mechanism: Orientdb provides shared locks and locks of other locks to control concurrent access to read and write operations.You can use the `Read Lock` and` write lock` sentences to obtain and release the lock. Programming code example: ODatabaseSession db = orientDB.open("mydatabase", "admin", "admin"); // Get the shared lock db.execute("READ LOCK myclass"); // Execute reading operation // Release the lock db.execute("UNLOCK myclass"); // Get his lock db.execute("WRITE LOCK myclass"); // Execute the writing operation // Release the lock db.execute("UNLOCK myclass"); db.close(); The above code shows how to use shared locks and locks to control concurrent access.Use the `Read Lock` statement to obtain the shared lock, perform reading operations, and then use the` unlock` statement to release the shared lock.Similarly, use the `Writ Lock` statement to get the lock, execute the writing operation, and then use the` UNLOCK` statement to release the lock. -HVCC: MVCC is a kind of unlocked concurrent control mechanism. It uses multiple versions to deal with read and write conflicts of concurrent transactions.Every transaction can see the database status before starting, not affected by other concurrent transactions. Programming code example: ODatabaseSession db = orientDB.open("mydatabase", "admin", "admin"); // Start reading transactions db.beginTransaction(); // Execute reading operation // End reading transaction db.commit(); // Start writing transactions db.begin(); // Execute the writing operation // End writing transactions db.commit(); db.close(); The above code shows how to use MVCC for concurrent control.Start reading transactions by calling the `Begintransaction" method, and perform reading operations in transactions, and then call the `Commit` method to end the transaction.Similarly, start writing transactions by calling the `Begin` method, and performing writing operations in the transaction, and then calling the` Commit` method to end the transaction. 【Configuration instructions】 In order to perform database transaction processing and concurrent control, we need to perform some related configurations in the ORIENTDB configuration file.Open the `Orientdb-Server-config.xml` file, and modify the configuration as follows: 1. Open transaction support: <orientdb> ... <network> <protocols> <protocol name="binary" implementation="com.orientechnologies.orient.server.network.protocol.binary.ONetworkProtocolBinary" implementationMap="com.orientechnologies.orient.server.network.protocol.binary.ONetworkProtocolBinary" /> ... </protocols> <listeners> <listener protocol="binary" socket="default" ip-address="0.0.0.0" port-range="2424-2430" /> ... </listeners> </network> ... <storages> <storage name="mydatabase" path="/path/to/database" userName="admin" userPassword="admin" loaded-at-startup="true"> <configuration> <properties> ... <entry name="cache.level1.enabled" value="true" /> <entry name="cache.level1.enabled" value="10000" /> ... <entry name="TX_LOG_TYPE" value="memory" /> <entry name="TX_USE_LOG" value="true" /> <entry name="TX_SYNCH" value="true" /> ... </properties> </configuration> </storage> </storages> ... </orientdb> In the above configuration, we mainly pay attention to related configuration items such as `tx_log_type`,` tx_use_log`, and `tx_synch`.`Tx_log_type` specifies the storage method of transaction logs, which uses memory storage here;` tx_use_log` indicates whether to open the transaction log to support the persistence of the transaction; `tx_synch` specifies the synchronization of transactions. 2. Concurrent control configuration: <orientdb> ... <storages> <storage name="mydatabase" path="/path/to/database" userName="admin" userPassword="admin" loaded-at-startup="true"> <configuration> <properties> ... <entry name="mvcc" value="true" /> ... </properties> </configuration> </storage> </storages> ... </orientdb> In the above configuration, we open MVCC concurrent control by adding the `MVCC` options under the` Properties` node. 【Summarize】 This article introduces the transaction processing and concurrent control mechanism of the OrientDB database.In the example code, the basic transaction processing process and lock mechanism, and the use of MVCC concurrent control.At the same time, relevant configuration description is given to help readers better understand and use these functions.Through reasonable use of transaction processing and concurrent control, the consistency and high composite performance of the database can be guaranteed.