Checks whether the lock named
str is free to use (that is, not locked).
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
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.
Content reproduced on this site is the property of its respective owners,
and this content is not reviewed in advance by MariaDB. The views, information and opinions
expressed by this content do not necessarily represent those of MariaDB or any other party.