Commit (data management)

In the context of computer science and data management, commit refers to the idea of making a set of tentative changes permanent. A popular usage is at the end of a transaction. A commit is an act of committing.

Data management

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. 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.

Revision control

Commits are also done for revision control systems for source code such as Subversion or Concurrent Versions System. A commit in the context of these version control systems refers to submitting the latest changes of the source code to the repository, and making these changes part of the head revision of the repository. Thus, when other users do an UPDATE or a checkout from the repository, they will receive the latest committed version, unless they specify they wish to retrieve a previous version of the source code in the repository. Version control systems also have similar functionality to SQL databases in that they allow rolling back to previous versions easily. In this context, a commit with version control systems is not as dangerous as it allows easy rollback, even after the commit has been done.

See also

• Atomic commit
• Two-phase commit protocol
• Three-phase commit protocol

Notes