每行调用1=2吗?

select orderId
into #sometmptbl
from orders
where 1=2

然而,当你在这上面做一个展示计划的时候,它实际上似乎要进入表/索引:

语句1的查询计划(第行) 1).

STEP 1
    The type of query is CREATE TABLE.

STEP 2
    The type of query is INSERT.
    The update mode is direct.

    FROM TABLE
        orders
    Nested iteration.
    Index : orders_idx1
    Forward scan.
    Positioning at index start.
    Index contains all needed columns. Base table will not be read.
    Using I/O Size 2 Kbytes for index leaf pages.
    With LRU Buffer Replacement Strategy for index leaf pages.
    TO TABLE
        #sometmptbl
    Using I/O Size 2 Kbytes for data pages.

报表的总估计I/O成本 1(第1行):632082。

这是否意味着索引中的每个条目都要计算1=2?有没有办法在固定的时间内做到这一点?

更新 :

以下是执行后的实际I/O开销,因此看起来实际读取数确实为0,因此不会影响性能:

Table: orders scan count 0, logical reads: (regular=0 apf=0 total=0), physical reads: (regular=0 apf=0 total=0), apf IOs used=0
Table: #sometmptbl_____00002860018595346 scan count 0, logical reads: (regular=1 apf=0 total=1), physical reads: (regular=0 apf=0 total=0), apf IOs used=0
Total actual I/O cost for this command: 2.
Total writes for this command: 3
0 row(s) affected.