IS_FREE_LOCK
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
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https://mariadb.com/kb/en/is_free_lock/