What are the methods to implement optimistic locking in SQL Server?

1 year ago
Jackson Davis
2 minutes

There are several ways to implement optimistic locking in SQL Server.

  1. Implement versioning: add a column for versions in the table, and increment the version number each time a record is updated. Before updating, check if the current version of the record matches the version obtained prior to the operation. If it matches, update the record and increment the version number; otherwise, it indicates that another transaction has already modified the record.
  2. Using timestamp: Add a timestamp column in the table and update it to the current time each time a record is updated. Before updating, check if the timestamp of the current record matches the one obtained before the operation. If they match, update the record; otherwise, it means another transaction has already modified the record.
  3. Utilizing hash values: Add a hash column in the table, calculate the hash value of the record each time it is updated, and save it in the hash column. When updating, first check if the hash value of the current record matches the hash value obtained before the operation. If they match, update the record; otherwise, it indicates that another transaction has already modified the record.
  4. Row versioning is used in SQL Server 2005 and later versions to implement optimistic locking. The ROWVERSION data type (also known as TIMESTAMP data type) can be used to store the version information of a record. When updating, the current version number of the record is checked to see if it matches the version number obtained before the operation. If they match, the record is updated along with its version number. Otherwise, it indicates that another transaction has already modified the record.

Different methods involve adding extra columns to the table in order to implement optimistic locking, and checking the values of these columns during updates to determine if another transaction has modified the record. The specific method used depends on the application scenario and requirements.

bannerAds