WAIT and NOWAIT

Control lock wait behavior. These clauses allow statements to wait for a specific timeout or fail immediately if a lock cannot be acquired.

Extended syntax so that it is possible to set innodb_lock_wait_timeout and lock_wait_timeout for the following statements:

Syntax

ALTER TABLE tbl_name [WAIT n|NOWAIT] ...
CREATE ... INDEX ON tbl_name (index_col_name, ...) [WAIT n|NOWAIT] ...
DROP INDEX ... [WAIT n|NOWAIT]
DROP TABLE tbl_name [WAIT n|NOWAIT] ...
LOCK TABLE ... [WAIT n|NOWAIT]
OPTIMIZE TABLE tbl_name [WAIT n|NOWAIT]
RENAME TABLE tbl_name [WAIT n|NOWAIT] ...
SELECT ... FOR UPDATE [WAIT n|NOWAIT]
SELECT ... LOCK IN SHARE MODE [WAIT n|NOWAIT]
TRUNCATE TABLE tbl_name [WAIT n|NOWAIT]

Description

The lock wait timeout can be explicitly set in the statement by using either WAIT n (to set the wait in seconds) or NOWAIT, in which case the statement will immediately fail if the lock cannot be obtained. WAIT 0 is equivalent to NOWAIT.

See Also

• Query Limits and Timeouts

• ALTER TABLE

• CREATE INDEX

• DROP INDEX

• DROP TABLE

• LOCK TABLES and UNLOCK TABLES

• OPTIMIZE TABLE

• RENAME TABLE

• SELECT

• TRUNCATE TABLE

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