topic Re: Performance Impact of Set Analysis vs Calculated Dimension in App Development

Performance Impact of Set Analysis vs Calculated Dimension

m_perreault — Sat, 16 Nov 2024 07:06:28 GMT

Hi All,

I have a line chart with Dimension

If(Date > '7/15/2018',Date)

and measure Sum(Sales)

I am wondering what is more optimal performance wise using my calculated dimension or using set analysis

Sum({<[Date] = {'>7/15/2018'}>}Sales)

I know the best thing to do would be create a flag in my script for Date > 7/15 and use that in my Set Analysis but its not always feasible to have so many flags.

Thanks!

Mark

Re: Performance Impact of Set Analysis vs Calculated Dimension

dplr-rn — Thu, 06 Dec 2018 18:18:10 GMT

Set analysis is vast majority of times always faster than if statements.
the reason is that your if statement gets calculated for each line which means it doesn't get cached.
while set analysis gets calculated once.

Possible exceptions are really complex aggr within the set.
Fastest ofcourse is flags. but as you say not always possible and not the most flexible

Re: Performance Impact of Set Analysis vs Calculated Dimension

sunny_talwar — Thu, 06 Dec 2018 18:28:05 GMT

Between the two, I would say Set analysis is always a better option.

Re: Performance Impact of Set Analysis vs Calculated Dimension

m_perreault — Thu, 06 Dec 2018 18:36:04 GMT

Thank you for your response. Could you explain further what you mean by

'the reason is that your if statement gets calculated for each line which means it doesn't get cached.
while set analysis gets calculated once.'

Re: Performance Impact of Set Analysis vs Calculated Dimension

dplr-rn — Thu, 06 Dec 2018 19:05:31 GMT

simply put it goes through each line of the data to evaluate your if condition.
while set analysis evaluates the set once per visualization (then again when filters are applied)

check these
https://community.qlik.com/t5/Qlik-Design-Blog/Why-is-it-called-Set-Analysis/ba-p/1468208
https://community.qlik.com/t5/Qlik-Design-Blog/A-Primer-on-Set-Analysis/ba-p/1468344