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Record locking is the technique of preventing simultaneous access to data in a database, to prevent inconsistent results. The classic example is demonstrated by two bank clerks attempting to update the same bank account for two different transactions. Clerks 1 and 2 both retrieve (i.e., copy) the account's record. Clerk 1 applies and saves a ...
A lock value block is associated with each resource. This can be read by any process that has obtained a lock on the resource (other than a null lock) and can be updated by a process that has obtained a protected update or exclusive lock on it. It can be used to hold any information about the resource that the application designer chooses.
In databases, and transaction processing (transaction management), snapshot isolation is a guarantee that all reads made in a transaction will see a consistent snapshot of the database (in practice it reads the last committed values that existed at the time it started), and the transaction itself will successfully commit only if no updates it has made conflict with any concurrent updates made ...
MySQL: MySQL Group Replication, a plugin for virtual synchronous multi-master with conflict handling and distributed recovery was released with 5.7.17. Cluster Projects: MySQL Cluster supports conflict detection and resolution between multiple masters since version 6.3 for true multi-master capability for the MySQL Server.
Interception-based: Most modern DAM systems collect what the database is doing by being able to “see” the communications between the database client and the database server. What DAM systems do is find places where they can view the communication stream and get the requests and responses without requiring participation from the database.
Optimistic concurrency control (OCC), also known as optimistic locking, is a non-locking 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.
update: Update the files in a working copy with the latest version from a repository; lock: Lock files in a repository from being changed by other users; add: Mark specified files to be added to repository at next commit; remove: Mark specified files to be removed at next commit (note: keeps cohesive revision history of before and at the remove.)
Names such as LAST_UPDATE, LAST_MODIFIED, etc. are common. Any row in any table that has a timestamp in that column that is more recent than the last time data was captured is considered to have changed. Timestamps on rows are also frequently used for opened locking so this column is often available.