In MySQL, when we use the LOCK TABLES command on a table, this lock will only be effective for the session executing the command, and will only affect attempts to access the table after the lock command. table session. This lock will have no direct impact on sessions that have been established and are interacting with the table before theLOCK TABLES command is executed. These established sessions can continue their operations on the table until they are completed or the session ends.
Impact of locking tables
- For the current session: In the current session, after the table is locked, other sessions will not be able to write to the table (for read locks) or do any operations (for write locks) , until the current session executes
UNLOCK TABLES. - For other already established sessions: These sessions can continue their operations because the lock was applied after they started interacting.
- For new sessions: Any new session started after the table is locked will be affected by the lock. If it's a read lock, they can read but not write to the table; if it's a write lock, they can't do anything to the table.
Important notes
- Lock restrictions:
LOCK TABLESare only valid within the session in which they are locked. If you need to lock the table across all sessions, consider other strategies such as modifying user permissions. - Performance impact: Locking tables for long periods of time can have a negative impact on database performance, especially in high-concurrency environments.
- Transaction processing: Using
LOCK TABLESwithin transaction processing requires special care as it may lead to complex locking situations and deadlocks.
Understanding these details about MySQL table locking is extremely valuable for development and operations work, especially when it comes to database management and team collaboration.