topic Re: When is it best to use sum(if()) over Set Analysis in an expression? in QlikView

When is it best to use sum(if()) over Set Analysis in an expression?

Fri, 08 Mar 2013 15:08:34 GMT

When is it best to use sum(if()) (or count() etc...) over Set Analysis in an object expression? Is there an advantage of one over the other as it relates to process speed?

Re: When is it best to use sum(if()) over Set Analysis in an expression?

kaushiknsolanki — Fri, 08 Mar 2013 16:43:45 GMT

Hi,

Kindly go though the attached file for clarification on each of the expression.

Regards,

Kaushik Solanki

Re: When is it best to use sum(if()) over Set Analysis in an expression?

hic — Fri, 08 Mar 2013 20:37:00 GMT

Often the Set analysis is faster than the Sum(If(...)). However, to make a fair comparison you must compare five different cases:

Sum(if(IsThisYear='True' , Sales))
The string comparison "IsThisYear='True'" is CPU-expensive. Avoid this construction!
Sum(if(Year=2013 , Sales))
A numeric comparison is a lot faster than a string comparison. But still slower than a booloean.
Sum(IsThisYear * Sales)
A multiplication works fine if the aggregation is a Sum. It does not work with Avg or Count. And multiplication is not very fast.
Sum(if(IsThisYear , Sales))
Using the "IsThisYear" as a boolean is faster than using it in a relational comparison.
Sum({$<IsThisYear={1}>} Sales)
Set analysis is often the fastest way.

My view is that alternative 4 or 5 are acceptably fast, but the three first constructions should be avoided.

HIC

Re: When is it best to use sum(if()) over Set Analysis in an expression?

Fri, 08 Mar 2013 21:34:13 GMT

Yes set analysis is the fastest way.

Re: When is it best to use sum(if()) over Set Analysis in an expression?

Mon, 18 May 2015 14:37:29 GMT

Thanks

This was really very helpful for me!

Regards,

Kuldeep