If there are no
FOREIGN KEY constraints,
InnoDB performs fast truncation by dropping
the original table and creating an empty one with the same
definition, which is much faster than deleting rows one by
When you use this fast truncation technique with the
enabled, the operating system can reuse the freed disk space.
For users of the InnoDB Plugin, the space is reclaimed
automatically, as described in
Reclaiming Disk Space with TRUNCATE TABLE. If you
do not have the InnoDB Plugin installed, issue the
OPTIMIZE TABLE statement to
free the disk space for the table.
If there are any
FOREIGN KEY constraints
that reference the table,
TRUNCATE TABLE by deleting rows
one by one, processing the constraints as it proceeds. If the
FOREIGN KEY constraint specifies
DELETE CASCADE, rows from the child
(referenced) table are deleted, and the truncated table
becomes empty. If the
constraint does not specify
TABLE statement deletes rows one by one and stops if
it encounters a parent row that is referenced by the child,
returning this error:
ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails (`test`.`child`, CONSTRAINT `child_ibfk_1` FOREIGN KEY (`parent_id`) REFERENCES `parent` (`id`))
In MySQL 5.5 and higher,
TABLE is not allowed for
tables referenced by foreign keys. For ease of upgrading,
rewrite such statements to use
AUTO_INCREMENT counter is reset to zero
TRUNCATE TABLE, regardless
of whether there is a
This is the same as a
statement with no
Truncate operations drop and re-create the table, which is much faster than deleting rows one by one, particularly for large tables.
Truncate operations cause an implicit commit.
Truncation operations cannot be performed if the session holds an active table lock.
Truncation operations do not return a meaningful value for the number of deleted rows. The usual result is “0 rows affected,” which should be interpreted as “no information.”
As long as the table format file
is valid, the table can be re-created as an empty table with
TRUNCATE TABLE, even if the
data or index files have become corrupted.
The table handler does not remember the last used
AUTO_INCREMENT value, but starts counting
from the beginning. This is true even for
normally do not reuse sequence values.
When used with partitioned tables,
TRUNCATE TABLE preserves the
partitioning; that is, the data and index files are dropped
and re-created, while the partition definitions
.par) file is unaffected.
Beginning with MySQL 5.1.32,
TABLE is treated for purposes of binary logging and
DROP TABLE followed
CREATE TABLE—that is, as
DDL rather than DML. This is due to the fact that, when using
InnoDB and other transactional
storage engines where the transaction isolation level does not
permit statement-based logging (
READ UNCOMMITTED), the statement was not
logged and replicated when using
MIXED logging mode. (Bug #36763) However, it is
still applied on replication slaves using
InnoDB in the manner described