Version-Controlled Updates

Version-controlled updates can help detect and resolve various data update conflicts.

You can use version-control updates to:

Detect and resolve conflicting updates
Resolve multiple primary conflicts when there is no single primary source
Make multiple requests to a single primary

Updates are accepted or rejected based on a version column that changes each time the row is updated. The version column can be a number that increases with each update, a timestamp, or some other value from a set of unique values.

To update a row, an application must provide the current value of the version column at the primary site. Typically, the value is provided as a parameter to a replicated stored procedure. The stored procedure at the primary site checks the version parameter and takes appropriate action if it detects a conflict. If the application chooses to roll back the transaction, it is written to the exceptions log.

Note: Managing update conflicts using version control requires careful planning and design. When there are multiple primaries, it is usually simpler and more effective to establish owners for each row of a table.