truncate
A DDL operation that removes the entire contents of a table, while leaving the table and related indexes intact. Contrast with drop. Although conceptually it has the same result as a DELETE statement with no WHERE clause, it operates differently behind the scenes: InnoDB creates a new empty table, drops the old table, then renames the new table to take the place of the old one. Because this is a DDL operation, it cannot be rolled back.
If the table being truncated contains foreign keys that reference another table, the truncation operation uses a slower method of operation, deleting one row at a time so that corresponding rows in the referenced table can be deleted as needed by any ON DELETE CASCADE clause. (MySQL 5.5 and higher do not allow this slower form of truncate, and return an error instead if foreign keys are involved. In this case, use a DELETE statement instead.
See also DDL.
See also drop.
See also foreign key.
See also rollback.