 |
In computer science and data management, a commit is the making of a set of tentative changes permanent, marking the end of a transaction and providing Durability to ACID transactions. A commit is an act of committing. The record of commits is called the commit log.
A COMMIT statement in SQL ends a transaction within a relational database management system (RDBMS) and makes all changes visible to other users. The general format is to issue a BEGIN WORK (or BEGIN TRANSACTION, depending on the database vendor) statement, one or more SQL statements, and then the COMMIT statement. Alternatively, a ROLLBACK statement can be issued, which undoes all the work performed since BEGIN WORK was issued. A COMMIT statement will also release any existing savepoints that may be in use.
In terms of transactions, the opposite of commit is to discard the tentative changes of a transaction, a rollback.
| Types | |
|---|---|
| Concepts | |
| Objects | |
| Components | |
| Functions | |
| Related topics | |
 | This computer science article is a stub. You can help Wikipedia by expanding it. |
In computer science, ACID is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequence of database operations that satisfies the ACID properties is called a transaction. For example, a transfer of funds from one bank account to another, even involving multiple changes such as debiting one account and crediting another, is a single transaction.
In computer science, transaction processing is information processing that is divided into individual, indivisible operations called transactions. Each transaction must succeed or fail as a complete unit; it can never be only partially complete.
Optimistic concurrency control (OCC), also known as optimistic locking, is a concurrency control method applied to transactional systems such as relational database management systems and software transactional memory. OCC assumes that multiple transactions can frequently complete without interfering with each other. While running, transactions use data resources without acquiring locks on those resources. Before committing, each transaction verifies that no other transaction has modified the data it has read. If the check reveals conflicting modifications, the committing transaction rolls back and can be restarted. Optimistic concurrency control was first proposed by H. T. Kung and John T. Robinson.
A database transaction symbolizes a unit of work, performed within a database management system against a database, that is treated in a coherent and reliable way independent of other transactions. A transaction generally represents any change in a database. Transactions in a database environment have two main purposes:
In the field of databases in computer science, a transaction log is a history of actions executed by a database management system used to guarantee ACID properties over crashes or hardware failures. Physically, a log is a file listing changes to the database, stored in a stable storage format.
Transact-SQL (T-SQL) is Microsoft's and Sybase's proprietary extension to the SQL used to interact with relational databases. T-SQL expands on the SQL standard to include procedural programming, local variables, various support functions for string processing, date processing, mathematics, etc. and changes to the DELETE and UPDATE statements.
In database systems, isolation determines how transaction integrity is visible to other users and systems.
In transaction processing, databases, and computer networking, the two-phase commit protocol (2PC) is a type of atomic commitment protocol (ACP). It is a distributed algorithm that coordinates all the processes that participate in a distributed atomic transaction on whether to commit or abort the transaction. This protocol achieves its goal even in many cases of temporary system failure, and is thus widely used. However, it is not resilient to all possible failure configurations, and in rare cases, manual intervention is needed to remedy an outcome. To accommodate recovery from failure the protocol's participants use logging of the protocol's states. Log records, which are typically slow to generate but survive failures, are used by the protocol's recovery procedures. Many protocol variants exist that primarily differ in logging strategies and recovery mechanisms. Though usually intended to be used infrequently, recovery procedures compose a substantial portion of the protocol, due to many possible failure scenarios to be considered and supported by the protocol.
In database technologies, a rollback is an operation which returns the database to some previous state. Rollbacks are important for database integrity, because they mean that the database can be restored to a clean copy even after erroneous operations are performed. They are crucial for recovering from database server crashes; by rolling back any transaction which was active at the time of the crash, the database is restored to a consistent state.
A database trigger is procedural code that is automatically executed in response to certain events on a particular table or view in a database. The trigger is mostly used for maintaining the integrity of the information on the database. For example, when a new record is added to the employees table, new records should also be created in the tables of the taxes, vacations and salaries. Triggers can also be used to log historical data, for example to keep track of employees' previous salaries.
A savepoint is a way of implementing subtransactions within a relational database management system by indicating a point within a transaction that can be "rolled back to" without affecting any work done in the transaction before the savepoint was created. Multiple savepoints can exist within a single transaction. Savepoints are useful for implementing complex error recovery in database applications. If an error occurs in the midst of a multiple-statement transaction, the application may be able to recover from the error without needing to abort the entire transaction.
The Access Database Engine is a database engine on which several Microsoft products have been built. The first version of Jet was developed in 1992, consisting of three modules which could be used to manipulate a database.
In computer science, a database cursor is a mechanism that enables traversal over the records in a database. Cursors facilitate subsequent processing in conjunction with the traversal, such as retrieval, addition and removal of database records. The database cursor characteristic of traversal makes cursors akin to the programming language concept of iterator.
The execution of a business process consists of one or more transactions. Each transaction may consist of several individual operations yet, as a whole, it moves the system between consistent states.
In the context of data management, autocommit is a mode of operation of a database connection. Each individual database interaction submitted through the database connection in autocommit mode will be executed in its own transaction that is implicitly committed. A SQL statement executed in autocommit mode cannot be rolled back.
Java Database Connectivity (JDBC) is an application programming interface (API) for the Java programming language, which defines how a client may access a database. It is a Java-based data access technology used for Java database connectivity. It is part of the Java Standard Edition platform, from Oracle Corporation. It provides methods to query and update data in a database, and is oriented toward relational databases. A JDBC-to-ODBC bridge enables connections to any ODBC-accessible data source in the Java virtual machine (JVM) host environment.
Versant Object Database (VOD) is an object database software product developed by Versant Corporation.
Apache Trafodion is an open-source Top-Level Project at the Apache Software Foundation. It was originally developed by the information technology division of Hewlett-Packard Company and HP Labs to provide the SQL query language on Apache HBase targeting big data transactional or operational workloads. The project was named after the Welsh word for transactions. As of April 2021, it is no longer actively developed.
A COMMIT statement in SQL ends a transaction within a relational database management system (RDBMS) and makes all changes visible to other users. The general format is to issue a BEGIN WORK statement, one or more SQL statements, and then the COMMIT statement. A COMMIT statement will also release any existing savepoints that may be in use. This means that once a COMMIT statement is issued, you can not rollback the transaction.
The syntax of the SQL programming language is defined and maintained by ISO/IEC SC 32 as part of ISO/IEC 9075. This standard is not freely available. Despite the existence of the standard, SQL code is not completely portable among different database systems without adjustments.
