Code action DI005 (Improvement) Rewrite table filter as scalar predicate
Description
Rewrite CALCULATE filter arguments as scalar predicates when possible, instead of using the FILTER function.
Example 1
Change:
CALCULATE([Total Sales], FILTER(Products, Products[Color] = "Red"))
To:
CALCULATE([Total Sales], KEEPFILTERS(Products[Color] = "Red"))
Example 2
Change:
CALCULATE([Total Sales], FILTER(ALL(Products), Products[Color] = "Red"))
To:
CALCULATE([Total Sales], Products[Color] = "Red")
Example 3
Change:
CALCULATE(
[Total Sales],
FILTER(
ALL(Products),
Products[Color] = "Red"
&& Products[Class] = "High-end"
)
)
To:
CALCULATE(
[Total Sales],
Products[Color] = "Red",
Products[Class] = "High-end"
)
Why is Tabular Editor suggesting this?
Filtering a table inside a CALCULATE filter argument is less efficient than filtering one or more columns from that table. By rewriting the filter as a scalar predicate, you make your code more efficient, consuming less memory and CPU resources.
For example, an expression such as FILTER(Sales, < condition >) will iterate over all rows in the Sales table, evaluating the condition for each row. In contrast, an expression such as Sales[Quantity] > 0 will only iterate over the Quantity column, which is much more efficient, and does not cause all the columns from the Sales table to be added to the filter context.
By using scalar predicates, you also make your code more concise and easier to read.
Behind the scenes, scalar predicates are syntax sugar for a table expression that also uses the FILTER function. However, the FILTER function is applied to a single column, which is more efficient than filtering the entire table.