MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6

12.14 Locking Functions

This section describes functions used to manipulate user-level locks.

Table 12.18 Locking Functions

Name Description
GET_LOCK() Get a named lock
IS_FREE_LOCK() Whether the named lock is free
IS_USED_LOCK() Whether the named lock is in use; return connection identifier if true
RELEASE_ALL_LOCKS() Release all current named locks
RELEASE_LOCK() Release the named lock