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

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

如果不小心使用Delete/Truncate从表中删除了所有数据。您可以回滚已提交的事务。恢复上次备份并运行事务日志，直到将要执行删除/截断操作。

以下相关信息来自一篇博客文章:

While working on database, we are using Delete and Truncate without knowing the differences between them. In this article we will discuss the difference between Delete and Truncate in Sql. Delete: Delete is a DML command. Delete statement is executed using a row lock,each row in the table is locked for deletion. We can specify filters in where clause. It deletes specified data if where condition exists. Delete activities a trigger because the operation are logged individually. Slower than Truncate because it Keeps logs Truncate Truncate is a DDL command. Truncate table always lock the table and page but not each row.As it removes all the data. Cannot use Where condition. It Removes all the data. Truncate table cannot activate a trigger because the operation does not log individual row deletions. Faster in performance wise, because it doesn't keep any logs. Note: Delete and Truncate both can be rolled back when used with Transaction. If Transaction is done, means committed then we can not rollback Truncate command, but we can still rollback Delete command from Log files, as delete write records them in Log file in case it is needed to rollback in future from log files. If you have a Foreign key constraint referring to the table you are trying to truncate, this won't work even if the referring table has no data in it. This is because the foreign key checking is done with DDL rather than DML. This can be got around by temporarily disabling the foreign key constraint(s) to the table. Delete table is a logged operation. So the deletion of each row gets logged in the transaction log, which makes it slow. Truncate table also deletes all the rows in a table, but it won't log the deletion of each row instead it logs the deallocation of the data pages of the table, which makes it faster. ~ If accidentally you removed all the data from table using Delete/Truncate. You can rollback committed transaction. Restore the last backup and run transaction log till the time when Delete/Truncate is about to happen.

在SQL Server 2005中，我相信你可以回滚截断

它方便的一个重要原因是，当您需要刷新数百万行表中的数据，但又不想重新构建它时。“Delete *”会花费很长时间，而Truncate对性能的影响可以忽略不计。

在这个例子中，Truncate也可以被rollback

begin Tran
delete from  Employee

select * from Employee
Rollback
select * from Employee