db_lock_table

5 database.mysqli.inc db_lock_table($table)
5 database.pgsql.inc db_lock_table($table)
5 database.mysql.inc db_lock_table($table)
6 database.pgsql.inc db_lock_table($table)
6 database.mysqli.inc db_lock_table($table)
6 database.mysql.inc db_lock_table($table)

Lock a table.

Related topics

Database abstraction layer
Allow the use of different database servers using the same code base.

File

includes/database.mysql.inc, line 335
Database interface code for MySQL database servers.

Code

function db_lock_table($table) {
  db_query('LOCK TABLES {' . db_escape_table($table) . '} WRITE');
}

Comments

Multiple table locks

Posted by Che Molava on August 28, 2011 at 11:29am

db_lock_table() will only lock one table at a time. If you need a lock while accessing multiple tables, or if you use table aliases, use a LOCK TABLES statement through db_query() instead. Bear in mind that this will make your code MySQL dependent so should be considered a last resort for specific concurrency problems.

From the MySQL documentation:

A session that requires locks must acquire all the locks that it needs in a single LOCK TABLES statement. While the locks thus obtained are held, the session can access only the locked tables.

If your statements refer to a table by means of an alias, you must lock the table using that same alias. It does not work to lock the table without specifying the alias...

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