Need to optimize/Rewrite this query..

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Need to optimize/Rewrite this query..

Chinna

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Points: 5408
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July 5, 2013 at 12:21 am

#274932

Implement a function with below logic in an efficient way ...Pass @var1 and return @var2 ...How can it be done as it does table scan now ??
DECLARE @Var1 VARCHAR(10)
DECLARE @Var2 VARCHAR(100)
SELECT @var2= var2 FROM #test
WHERE var1 = @Var1
Thanks in advance
Thanks,
Chinna
Its the Journey which gives you Happiness not the Destination-- Dan Millman

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Phil Parkin SSC Guru Points: 246686 More actions · Answer 1

Sri8143 (7/5/2013)
Implement a function with below logic in an efficient way ...Pass @var1 and return @var2 ...How can it be done as it does table scan now ??
DECLARE @Var1 VARCHAR(10)
DECLARE @Var2 VARCHAR(100)
SELECT @var2= var2 FROM #test
WHERE var1 = @Var1
Thanks in advance

Try creating an index on your temp table before running that query - something like this:

create nonclustered index ix_test_var1 on #test(var1) include(var2)

If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.

ChrisM@Work SSC Guru Points: 186127 More actions · Answer 2

ALTER FUNCTION [dbo].[IF_GetVar2]

(@Var1 VARCHAR(10))

RETURNS TABLE WITH SCHEMABINDING AS

RETURN

SELECT var2

FROM test

WHERE var1 = @Var1

;

GO

-- Testing:

SELECT var2 FROM IF_GetVar2('Somevalue')

-- Examine the execution plan and create a new index

-- on table 'test' to support seeks if necessary - as in Phil's post.

^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden

Chinna SSCertifiable Points: 5408 More actions · Answer 3

Thanks Guys for the response.. But just want to know if there is a workaround for this issue using crossapply ?

AS it is looping through all the records now ..

Thanks,
Chinna

Its the Journey which gives you Happiness not the Destination-- Dan Millman

ChrisM@Work SSC Guru Points: 186127 More actions · Answer 4

What do you mean by 'looping'? A table or clustered index scan? You can incorporate an iTVF into a query using APPLY but that won't help at all if there isn't a supporting index for the query.

^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden