Optimistic concurrency control: Difference between revisions

Revision as of 08:27, 29 January 2007

Revision as of 00:36, 2 February 2007

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==Web usage==

The [[Stateless_server|stateless]] nature of [[HTTP]] makes locking super feasibleinfeasible for web user interfaces. It's common for a user to start editing a record, then leave without following a "cancel" or "logout" link. If locking is used, other users who attempt to edit the same record must wait until the first user's lock expires.

OCC is a natural choice. It is simple to implement and avoids unnecessary waiting or silently overwritten records. Typically the [[Form (web)|form]] presented to the user includes a hidden field with the record's original content, a timestamp, a sequence number, or an opaque token. On submit, this is compared against the database. If it differs, the conflict resolution algorithm is activated.