%YAML 1.2
---
urn: extension:io.substrait:functions_aggregate_approx
aggregate_functions:
- name: "approx_count_distinct"
description: >-
Calculates the approximate number of rows that contain distinct values of the expression argument using
HyperLogLog. This function provides an alternative to the COUNT (DISTINCT expression) function, which
returns the exact number of rows that contain distinct values of an expression. APPROX_COUNT_DISTINCT
processes large amounts of data significantly faster than COUNT, with negligible deviation from the exact
result.
impls:
- args:
- name: x
value: any
nullability: DECLARED_OUTPUT
decomposable: MANY
intermediate: binary
return: i64