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 replication.

See also


Comments loading...