November 20, 2007 at 6:02 am
Declare @a -- Same structure as B. In other words a temporary table with same structure as B
(
ID
)
Delete
B
From
@a TempA
inner join
B
on
TempA.ID = B.ID
-- This update will never execute as the common records have already been deleted .... My doubt
-- being that will this piece of code effect the execution time of a stored proc
Update
B
Set
ID = TempA.ID
From
@a TempA
inner join
B
on
TempA.ID = B.ID
-- In the following piece of code an unnecessary left outer join has been used ... will this piece of
-- add to the execution time of the code even in case there are no rows common to the database
-- there for the left outer join will result in all rows with B.ID as Null
Insert into B
(
ID
)
Values
(
Select
ID
From
@a TempA
left outer join
B
on
TempA.ID = B.ID
Where
B.ID is Null
)
My basic question being that even in case there are no rows common to the table will the performance of the query without the join be better than the performance of the query with the left join
November 20, 2007 at 6:52 am
In my view, redundant code
a) any unnecessary code is a performance overhead. But to what extent it affects depends on the scenario. Think of this code being called from a webpage accessed by millions. The redundant code simply takes time, resource without achiving anything.
b) redundaant code reduces readability of code and causes confusion and in turn maintenance becomes difficult
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