Rules / Maintenance

Remove unnecessary measures

warning UNNECESSARY_MEASURES · ported · model layer · scope: Measure

What it checks

Hidden measures, or measures on hidden tables, that no DAX expression references.

Each finding names the measure as DAX writes it, [Total Sales Legacy], without the table it sits on.

Example

Fires the rule

table Sales
	column Amount
		dataType: decimal
		sourceColumn: Amount

	measure 'Total Sales' = SUM('Sales'[Amount])
		formatString: #,0

	measure 'Total Sales Legacy' = SUMX('Sales', 'Sales'[Amount])
		isHidden
		formatString: #,0

After the fix

table Sales
	column Amount
		dataType: decimal
		sourceColumn: Amount

	measure 'Total Sales' = SUM('Sales'[Amount])
		formatString: #,0

Why it matters

A hidden measure that no other measure uses can only be reached by a report that already had it, so it is either dead or a hidden dependency that breaks the day someone deletes it as dead. Either way it belongs in the open or in the bin.

How to fix it

In Power BI Desktop, right-click the measure in the Data pane and choose Delete from model, or, if reports still use it, clear Is hidden in the Properties pane so the dependency is visible to the next person. In the TMDL file, remove the measure block from its table, or remove isHidden from under it. Search the project for the measure's name before you delete it: this rule has already searched the model's DAX (measures with their format strings and KPIs, calculated columns and tables, calculation items, row-level security filters, and user-defined functions), so what a search adds is the report files, which this rule does not read, and anything else in the model that names the measure.

When to ignore it

Report usage is the case to check first. A hidden measure that a visual or a report-level filter binds to directly is in use, but this rule reads the model only, as the source rule does, so it reports that measure all the same. When the report is in the input, NOT_REACHED_FROM_REPORT says which fields that report never reaches; other reports on the same model are still yours to open before you delete a measure. A measure you have written for a calculation item or a measure you have not finished is a fair thing to leave for as long as that lasts. A hidden measure nobody can name a caller for is what the rule is for.

To ignore this rule on one object, add annotation pbiplint.ignore = UNNECESSARY_MEASURES under the object in its TMDL file. Power BI Desktop keeps the annotation. To turn the rule off for a whole project, set "UNNECESSARY_MEASURES": "off" under rules in pbiplint.config.json.

Quirks

References from calculation items and from other hidden measures count as usage.
Report usage is not visible to this rule. A hidden measure used only by a visual is still flagged.
A row-level security filter counts as a DAX expression, so a measure named in one is used.
A measure named in a user-defined function counts as referenced, even when nothing calls the function, as Tabular Editor counts it. When the report is in the input, NOT_REACHED_FROM_REPORT follows the calls, so it reports a measure that only an uncalled function uses.
A bare [Measure] reference resolves by name across the whole model, ignoring letter case, so it counts wherever the measure lives. DAX is read token by token, so a measure named only inside a string or a comment is not a use.
While a model file has a parse issue that can take a declaration out of the model, such as a line indented with spaces, or pbiplint could not open a model file or folder at all, the rule reports nothing, because the DAX that references the measure could be in what pbiplint missed, and pbiplint does not guess what a file it could not read says. The skipped line gives the reason, a model file could not be fully read, and the file's own PARSE_ISSUE finding names it, or a notice does for a file or folder pbiplint could not open.

UNNECESSARY_COLUMNS makes the same test on hidden columns, and reads relationships, hierarchies, and security rules as well as expressions.
MEASURES_SHOULD_NOT_BE_DIRECT_REFERENCES_OF_OTHER_MEASURES reports a measure whose whole expression is a reference to another measure. That reference counts as usage here, so deleting the alias can bring the measure it named into this rule.
PROVIDE_FORMAT_STRING_FOR_MEASURES reads only visible measures, which this rule never reports, so unhiding a measure to keep it moves it into that rule's scope, provided its table is visible too.
UDF_NOT_CALLED reports a user-defined function nothing calls. A measure that such a function names counts as used here, so deleting the function can bring the measure into this rule.

Ported from Microsoft's Best Practice Analyzer ruleset (opens in a new tab).

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