Daily DAX : Day 76 ROLLUPDISSUBTOTAL

 The ROLLUPADDISSUBTOTAL function in Power BI's Data Analysis Expressions (DAX) language is used to add or remove subtotal rows from a result set that has been generated by a ROLLUP function. Here's a breakdown of its functionality and main use case:

Function Syntax:

dax

ROLLUPADDISSUBTOTAL(<expression>, <isSubtotal>)

Parameters:

    <expression>: The column or expression for which you want to determine whether the current row is a subtotal.

    <isSubtotal>: A boolean expression that evaluates to TRUE if the current row is a subtotal, otherwise FALSE.

How it Works:

    When used within a ROLLUP context, ROLLUPADDISSUBTOTAL can modify how subtotals are displayed or calculated:

        If isSubtotal is TRUE, it means the function will consider the current row as a subtotal.

        If isSubtotal is FALSE, it excludes the current row from being treated as a subtotal.

Main Use Case:

    Custom Subtotals in Pivot Tables: This function is particularly useful when you want to control the granularity of subtotal information in reports or pivot tables. For instance:

        You might want to show subtotals for certain categories but not for others within the same dataset.

        It allows for dynamic manipulation of how data aggregations appear based on the context or specific business rules.

    Performance Optimization: By controlling which rows are considered for subtotals, you can potentially optimize query performance by reducing unnecessary calculations for subtotal rows when they are not needed.

    Enhanced Data Visualization: In scenarios where visual clarity is key, you can use ROLLUPADDISSUBTOTAL to refine how data is summarized or displayed, making charts or tables more intuitive or tailored to specific analytical needs.

Example:

Here's a hypothetical example to illustrate its use:

dax

SalesTable = 

ROLLUP(

    SUMMARIZE(

        Sales,

        Sales[Category],

        Sales[Subcategory]

    ),

    Sales[Category],

    Sales[Subcategory]

)

ModifiedTable = ADDCOLUMNS(

    SalesTable,

    "IsSubtotal", ROLLUPADDISSUBTOTAL(Sales[Category], ISFILTERED(Sales[Subcategory]))

)

In this example, ROLLUPADDISSUBTOTAL would flag rows as subtotals (IsSubtotal column) only if Subcategory is filtered, allowing for conditional display or calculation of subtotals based on the presence of that filter.

Remember, ROLLUPADDISSUBTOTAL is not a standalone function but works in conjunction with ROLLUP to manage how subtotals are handled within your data model.

https://dax.guide/rollupaddissubtotal/