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The introduction of granular (subset) locks creates the possibility for a situation called deadlock. Deadlock is possible when incremental locking (locking one entity, then locking one or more additional entities) is used. To illustrate, if two bank customers asked two clerks to obtain their account information so they could transfer some money ...
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 ...
Isolation is typically enforced at the database level. However, various client-side systems can also be used. It can be controlled in application frameworks or runtime containers such as J2EE Entity Beans [2] On older systems, it may be implemented systemically (by the application developers), for example through the use of temporary tables.
Every transaction implicitly begins with the first "Update" type of entry for the given Transaction ID, and is committed with "End Of Log" (EOL) entry for the transaction. During a recovery, or while undoing the actions of an aborted transaction, a special kind of log record is written, the Compensation Log Record (CLR), to record that the ...
A wait-for graph in computer science is a directed graph used for deadlock detection in operating systems and relational database systems.. In computer science, a system that allows concurrent operation of multiple processes and locking of resources and which does not provide mechanisms to avoid or prevent deadlock must support a mechanism to detect deadlocks and an algorithm for recovering ...
DynamoDB uses conditional update as an implementation of OCC. [17] Kubernetes uses OCC when updating resources. [18] YugabyteDB is a cloud-native database that primarily uses OCC. [19] Firestore is a NoSQL database by Firebase that uses OCC in its transactions. Apache Iceberg uses OCC to update tables and run maintenance operations on them.
The data part always keeps the last committed version. The undo log enables the recreation of older versions of data. The main inherent limitation of this latter approach is that when there are update-intensive workloads, the undo log part runs out of space and then transactions are aborted as they cannot be given their snapshot.
The sequence diagram showing the success path of Two Phase Commit protocol created with FizzBee. In transaction processing, databases, and computer networking, the two-phase commit protocol (2PC, tupac) is a type of atomic commitment protocol (ACP).