Set analysis is one of the more powerful tools you can use in Qlik Sense and QlikView. Its syntax is sometimes perceived as complicated, but once you learn it, you can achieve fantastic things. There is now an additional way of writing the Set expression, that may simplify your code.
Set analysis is a way to define an aggregation scope different from current selection. Think of it as a way to define a conditional aggregation. The condition – or filter – is written inside the aggregation function. For example, the following will sum the amounts pertaining to 2021:
Sum({<Year={2021}>} Amount)
This syntax however has a couple of drawbacks: First, it is not easy to combine a master measure with different set expressions, since the set expression is hard-coded inside the master measure. Secondly, if you have an expression with multiple aggregations, you need to write the same set expression in every aggregation function.
Therefore, we introduce an additional position for set expressions: They can now be written outside the aggregation function and will then affect all subsequent aggregations. This means that the below expression is allowed:
For master measures, this change will allow a very powerful re-usability: You can now add set expressions to tweak existing master measures:
{<Year={2021}>} [Master Measure]
Lexical scoping
The outer set expression will affect the entire expression, unless it is enclosed in round brackets. If so, the brackets define the lexical scope. For example, in the following expression, the set expression will only affect the aggregations inside the brackets - the Avg() call will not be affected.
The set expression must be placed in the beginning of the lexical scope.
Context and inheritance
Aggregation functions that lack set expression, will inherit the context from the outside: In earlier versions the context was always defined by the current selection. Now we have added the possibility of having the context defined by a set expression. So, now “context” means current selectionor an outer set expression.
Inner set expression
If an aggregation function already contains a set expression, this will be merged with the context. The same merging rules as today will apply:
An inner set expression with a set identifier will NOT inherit from the context. It will inherit the selection from the set identifier instead.
An inner set expression that lacks set identifier – it has only a set modifier – will inherit from the context.
How the merge is made depends on the set assignment for the field; whether it is made with an equals sign “=” or with an implicit set operator, e.g. “+=”. The logic is identical to how current selection is merged with a set expression.
Examples:
{<OuterSet>} Sum( {<InnerSet>} Field ) The OuterSet will be inherited into the InnerSet, since the inner set lacks set identifier.
{<OuterSet>} Sum( {$<InnerSet>} Field ) The OuterSet will not be inherited into the InnerSet, since the inner set expression contains a set identifier.
Aggr()
The set expression of the outer aggregation will never be inherited into the inner aggregation. But a set expression outside the outer aggregation will be inherited into both.
Examples:
Sum({<Set1>} Aggr(Count({<Set2>} Field ))) The Set1 will not be inherited into Set2.
{<OuterSet>} Sum({<Set1>} Aggr(Count({<Set2>} Field ))) The OuterSet will be inherited into both Set1 and Set2.
Summary
Nothing changes for existing set expressions – they will continue to work. But with this additional syntax we hope to simplify your work and your expressions and allow you to re-use your master measures more effectively.
This change affects all Qlik Sense editions from the August 2022 release. It will also be included in the next major QlikView release, planned for late spring 2023.
I like this a lot at first blush - I think it will be even more meaningful to Qlik developers than my previous favorite, which was master measures by reference.
I've being using this new set analysis for a few weeks now, it's great.
However something funny has happened since yesterday. I had a table with several expressions in, a couple of of them using 'old' syntax and some using the new syntax e.g.
This was working fine until today, when the other measures (the ones using 'old' set analysis) in the table went blank. Nothing in the app had changed between yesterday and today (no new design changes, no data reloads).
After tearing our hair out we found that putting the SUM at the start of the expression resolved the problem
I'm really puzzled by this...have I done something wrong in the new set analysis syntax above? The solution that we've found looks weird, somewhere between the 'old' and 'new' set analysis syntax.
I feel like there's a bug that's crept in since yesterday, where the new set analysis syntax is affecting charts and tables with multiple measures.
I am also experiencing the behaviour explained by @RoryMcHugh-Catalyst since yesterday. If you need more details in order to replicate the bug contact me.
I've got the same issue. Your solution didn't make any difference
({<YearsAgo = {3} >} SNSalesEquipAllYrs)
It was fixed by retyping what I have above
NB. I think I had a *= by mistake.
{<YearsAgo *= {3} >} SNSalesEquipAllYrs
When I retyped I lift the * out. But not 100% sure. But hope *= will still work when required
Thanks
Further testing shows that sometimes *= works (without the ()) and sometimes it doesn't. But without *= and using instead just = it always works so far
I then used this master measure in a table measure as follows
{<YearsAgo = {0,1,2,3,4,5}>} SNSalesEquipAllYrs
If this measure was immediately before other measures on the table that didn't use YearsAgo it filters these measures as well. But only if YearsAgo wasn't used in a measure and only if it was just before other measures that didn't use YearsAgo
I've read through your post and... Just wondering - is there any way to override inner Set analysis (particularly defined in master measure) with outer Set analysis?
Let's say we want to define a "default" master measure, that will by calculate sales for current year
This calculation would be valid unless the outer expression (e.g. in derived master measure) says otherwise. Let's say we want to define another master measure for Last Year Sales using the original Sales Master Measure.
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