dcountif() (aggregation function)

Returns an estimate of the number of distinct values of Expr of rows for which Predicate evaluates to true.

  • Can be used only in context of aggregation inside summarize.

Read about the estimation accuracy.

Syntax

summarize dcountif(Expr, Predicate, [, Accuracy])

Arguments

  • Expr: Expression that will be used for aggregation calculation.
  • Predicate: Expression that will be used to filter rows.
  • Accuracy, if specified, controls the balance between speed and accuracy.
    • 0 = the least accurate and fastest calculation. 1.6% error
    • 1 = the default, which balances accuracy and calculation time; about 0.8% error.
    • 2 = accurate and slow calculation; about 0.4% error.
    • 3 = extra accurate and slow calculation; about 0.28% error.
    • 4 = super accurate and slowest calculation; about 0.2% error.

Returns

Returns an estimate of the number of distinct values of Expr of rows for which Predicate evaluates to true in the group.

Example

PageViewLog | summarize countries=dcountif(country, country startswith "United") by continent

Tip: Offset error

dcountif() might result in a one-off error in the edge cases where all rows pass, or none of the rows pass, the Predicate expression