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 Performance improvement on low hit rate query
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marko_1
Starting Member

1 Posts

Posted - 11/08/2012 :  12:31:01  Show Profile  Reply with Quote
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

USA
1974 Posts

Posted - 11/09/2012 :  03:17:41  Show Profile  Visit chadmat's Homepage  Reply with Quote
@prsi_no is NULL for every execution. Is that your intention?

-Chad
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