IS_USED_LOCK

Check who holds a named lock. This function returns the connection identifier of the client holding the lock, or NULL if the lock is free.

Syntax

IS_USED_LOCK(str)

Description

Checks whether the lock named str is in use (that is, locked). If so, it returns the connection identifier of the client that holds the lock. Otherwise, it returns NULL. str is case insensitive.

If the metadata_lock_info plugin is installed, the Information Schema metadata_lock_info table contains information about locks of this kind (as well as metadata locks).

Statements using the IS_USED_LOCK function are not safe for statement-based replication.

See Also

• GET_LOCK

• RELEASE_LOCK

• IS_FREE_LOCK

• RELEASE_ALL_LOCKS

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