How Level of Detail Expressions Work in Tableau

In Tableau, expressions referencing unaggregated datasource columns are computed for each row in the underlying table. In this case, the dimensionality of the expression is row level.
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By contrast, expressions referencing aggregated data source columns are computed at the dimensionality defined by the dimensions in the view.
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Dimension and set fields placed on any of the locations highlighted in the following image contribute to the view level of detail:
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Before level of detail expressions were supported in Tableau, it was not possible to create calculations at a level of detail other than the view level. For example, if you attempt to save the following expression, Tableau displays the error message: “Cannot mix aggregate and non-aggregate arguments with this function”:
https://help.tableau.com/current/pro/desktop/en-us/calculati...

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Note added at 39 мин (2022-11-23 16:19:37 GMT)
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In this article
Row Level Expressions and View Level Expressions
Limitations for Level of Detail Expressions
Level of Detail Expressions Can Be Dimensions or Measures
Filters and Level of Detail Expressions
Aggregation and Level of Detail Expressions
Level of Detail Expression is Coarser Than View Level of Detail
Level of Detail Expression is Finer Than View Level of Detail
Adding a Level of Detail Expression to the View
Data Source Constraints for Level of Detail Expressions
https://help.tableau.com/current/pro/desktop/en-us/calculati...