“Truncate不会记录任何东西”是正确的。我想更进一步:

Truncate不会在事务的上下文中执行。

截断比删除的速度优势应该是明显的。根据你的情况，这种优势从微不足道到巨大不等。

然而，我看到截断无意中破坏了引用完整性，并违反了其他约束。通过在事务外部修改数据而获得的权力，必须与在没有安全网的情况下走钢丝时继承的责任相平衡。

通过发出TRUNCATE TABLE语句，您将指示SQL Server删除表中的每条记录，而不进行任何日志记录或事务处理。

对于SQL Server或MySQL，如果有一个带有自动递增的PK, truncate将重置计数器。

DELETE The DELETE command is used to remove rows from a table. A WHERE clause can be used to only remove some rows. If no WHERE condition is specified, all rows will be removed. After performing a DELETE operation you need to COMMIT or ROLLBACK the transaction to make the change permanent or to undo it. Note that this operation will cause all DELETE triggers on the table to fire. TRUNCATE TRUNCATE removes all rows from a table. The operation cannot be rolled back and no triggers will be fired. As such, TRUCATE is faster and doesn't use as much undo space as a DELETE. DROP The DROP command removes a table from the database. All the tables' rows, indexes and privileges will also be removed. No DML triggers will be fired. The operation cannot be rolled back. DROP and TRUNCATE are DDL commands, whereas DELETE is a DML command. Therefore DELETE operations can be rolled back (undone), while DROP and TRUNCATE operations cannot be rolled back.

来自:http://www.orafaq.com/faq/difference_between_truncate_delete_and_drop_commands

一眨眼的功夫就不能做DDL。

对原始答案的一个小修正——删除也会产生大量的重做(因为undo本身是由重做保护的)。这可以从autotrace输出中看到:

SQL> delete from t1;

10918 rows deleted.

Elapsed: 00:00:00.58

Execution Plan
----------------------------------------------------------
   0      DELETE STATEMENT Optimizer=FIRST_ROWS (Cost=43 Card=1)
   1    0   DELETE OF 'T1'
   2    1     TABLE ACCESS (FULL) OF 'T1' (TABLE) (Cost=43 Card=1)




Statistics
----------------------------------------------------------
         30  recursive calls
      12118  db block gets
        213  consistent gets
        142  physical reads
    3975328  redo size
        441  bytes sent via SQL*Net to client
        537  bytes received via SQL*Net from client
          4  SQL*Net roundtrips to/from client
          2  sorts (memory)
          0  sorts (disk)
      10918  rows processed