Performance improvement on low hit rate query

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Performance improvement on low hit rate query

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Topic

marko_1
Starting Member

1 Post

Posted - 2012-11-08 : 12:31:01

I was asked to think of an example database in which an index would improve the performance of a low hit rate query.

declare @prsi_no int
declare @L int, @i int, @x datetime, @y datetime, @z real, @u datetime
declare @s varchar(1000)
set @x = getdate() -- start time
select x = @x
set @i=1
while @i < 10000 -- N
begin
begin tran

set @s = 'select count(*) from dbo.Asg1_tbl where prsi_no = ' + str(@prsi_no)
exec(@s)
commit tran
set @i = @i + 1
end
set @y= getdate()
select y = @y
set @z = datediff(ms, @x, @y)
select 'Run time = ' + cast(@z as varchar(20)) + ' miliseconds.'
go

select * from dbo.Asg1_tbl where prsi_no = ceiling (rand()*10000)

I used this code to test the speed with a primary key on and with no primary key to test the speed improvement..

Anyone have an what code to use to generate a random number and also how to tabulate results??

chadmat
The Chadinator

1974 Posts

Posted - 2012-11-09 : 03:17:41

@prsi_no is NULL for every execution. Is that your intention?

-Chad

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