tabelllåser

Tabelllåser, often translated as table locks, are a mechanism used in database management systems to control concurrent access to data. When a transaction requires access to a table, it may acquire a lock on that table. This lock prevents other transactions from modifying or in some cases, even reading, the locked table until the lock is released. The primary purpose of table locks is to ensure data integrity and consistency, especially in environments where multiple users or processes are interacting with the database simultaneously.

There are different types of table locks, most commonly shared locks and exclusive locks. A shared lock, also known as a read lock, allows multiple transactions to read the table concurrently but prevents any transaction from writing to it. An exclusive lock, or write lock, grants a single transaction exclusive access to the table, preventing both reads and writes by other transactions. When a transaction is finished with its operations on the table, it releases the lock, allowing other waiting transactions to acquire the necessary locks and proceed.

The use of table locks can sometimes lead to performance issues. If a transaction holds a lock for an extended period, it can block other transactions, leading to delays and reduced throughput. This phenomenon is known as lock contention. Database systems employ various strategies to manage locks efficiently, including different locking granularities (e.g., row-level locks, page-level locks, or table-level locks), lock escalation, and deadlock detection and resolution mechanisms, to minimize the negative impact of locking on performance.