Syntax
------

LOCK TABLE[S]
  tbl_name [[AS] alias] lock_type
  [, tbl_name [[AS] alias] lock_type] ...
  [WAIT n|NOWAIT]

lock_type:
  READ [LOCAL]
 | [LOW_PRIORITY] WRITE
 | WRITE CONCURRENT


Description
-----------

The lock_type can be one of:

+---------------------------+------------------------------------------------+
| Option                    | Description                                    |
+---------------------------+------------------------------------------------+
| READ                      | Read lock, no writes allowed                   |
+---------------------------+------------------------------------------------+
| READ LOCAL                | Read lock, but allow concurrent inserts        |
+---------------------------+------------------------------------------------+
| WRITE                     | Exclusive write lock. No other connections     |
|                           | can read or write to this table                |
+---------------------------+------------------------------------------------+
| LOW_PRIORITY WRITE        | Exclusive write lock, but allow new read       |
|                           | locks on the table until we get the write      |
|                           | lock.                                          |
+---------------------------+------------------------------------------------+
| WRITE CONCURRENT          | Exclusive write lock, but allow READ LOCAL     |
|                           | locks to the table.                            |
+---------------------------+------------------------------------------------+

MariaDB enables client sessions to acquire table locks explicitly for the
purpose of cooperating with other sessions for access to tables, or to prevent
other sessions from modifying tables during periods when a session requires
exclusive access to them. A session can acquire or release locks only for
itself. One session cannot acquire locks for another session or release locks
held by another session.

Locks may be used to emulate transactions or to get more speed when updating
tables.

Table locks can be acquired for base tables or views. To use LOCK TABLES, you
must have the LOCK TABLES privilege, and the SELECT privilege for each object
to be locked. See GRANT

For view locking, LOCK TABLES adds all base tables used in the view to the set
of tables to be locked and locks them automatically. If you lock a table
explicitly with LOCK TABLES, any tables used in triggers are also locked
implicitly, as described in Triggers and Implicit Locks.


MariaDB starting with 10.3.0
----------------------------

WAIT/NOWAIT
-----------

Set the lock wait timeout. See WAIT and NOWAIT.

Limitations
-----------

* LOCK TABLES doesn't work when using Galera cluster.   You may experience
crashes or locks when used with Galera.
* LOCK TABLES works on XtraDB/InnoDB tables only if the innodb_table_locks
system variable is set to 1 (the default) and autocommit is set to 0 (1 is
default). Please note that no error message will be returned on LOCK TABLES
with innodb_table_locks = 0.
* LOCK TABLES implicitly commits the active transaction, if any. Also,
starting a transaction always releases all table locks acquired with LOCK
TABLES. This means that there is no way to have table locks and an active
transaction at the same time. The only exceptions are the transactions in
autocommit mode. To preserve the data integrity between transactional and
non-transactional tables, the GET_LOCK() function can be used.
* When using LOCK TABLES on a TEMPORARY table, it will always be locked with a
WRITE lock.
* While a connection holds an explicit read lock on a table, it cannot modify
it. If you try, the following error will be produced:

ERROR 1099 (HY000): Table 'tab_name' was locked with a READ lock and can't be
updated

* While a connection holds an explicit lock on a table, it cannot access a
non-locked table. If you try, the following error will be produced:

ERROR 1100 (HY000): Table 'tab_name' was not locked with LOCK TABLES

* While a connection holds an explicit lock on a table, it cannot issue the
following: INSERT DELAYED, CREATE TABLE, CREATE TABLE ... LIKE, and DDL
statements involving stored programs and views (except for triggers). If you
try, the following error will be produced:

ERROR 1192 (HY000): Can't execute the given command because you have active
locked tables or an active transaction

* LOCK TABLES can not be used in stored routines - if you try, the following
error will be produced on creation:

ERROR 1314 (0A000): LOCK is not allowed in stored procedures

URL: https://mariadb.com/kb/en/lock-tables/