parallelitätskontrolle

Parallelitätskontrolle, also known as concurrency control, is a crucial aspect of database management and distributed systems. It deals with the problem of managing simultaneous access to shared data by multiple processes or threads. The primary goal of parallelitätskontrolle is to ensure data consistency and integrity when operations are interleaved. Without proper control, concurrent operations can lead to race conditions, dirty reads, non-repeatable reads, and phantom reads, all of which can corrupt the data.

Various techniques are employed for parallelitätskontrolle. Locking is a common mechanism, where a transaction acquires a lock on a data item before accessing it and releases it afterward. Different types of locks exist, such as shared locks (for reading) and exclusive locks (for writing). Deadlocks, a situation where two or more transactions are waiting indefinitely for each other to release locks, are a potential issue with locking mechanisms and require deadlock detection and resolution strategies.

Another approach is timestamp ordering, which assigns a unique timestamp to each transaction and uses these timestamps to determine the order of operations. Multiversion concurrency control (MVCC) is a more advanced technique that maintains multiple versions of data items. This allows readers to access older versions of data without blocking writers, thus improving concurrency. Optimistic concurrency control assumes that conflicts are rare and checks for conflicts only at the commit time, rolling back transactions if conflicts are detected. The choice of parallelitätskontrolle mechanism depends on factors like the system's architecture, performance requirements, and the likelihood of conflicts.