IS_FREE_LOCK

Check if a named lock is free. This function returns 1 if the specified lock is available (not currently held), and 0 if it is in use.

Syntax

IS_FREE_LOCK(str)

Description

Checks whether the lock named str is free to use (that is, not locked). Returns 1 if the lock is free (no one is using the lock),0 if the lock is in use, and NULL if an error occurs (such as an incorrect argument, like an empty string or 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_FREE_LOCK function are not safe for statement-based replication.

See Also

• GET_LOCK

• RELEASE_LOCK

• IS_USED_LOCK

• RELEASE_ALL_LOCKS

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