ARRAY_APPROX_COUNT_DISTINCT

Returns an approximate count of distinct elements in an array, ignoring NULL values. This uses the same HyperLogLog-based estimator as APPROX_COUNT_DISTINCT.

Syntax

ARRAY_APPROX_COUNT_DISTINCT(<array>)

Return Type

BIGINT

Examples

SELECT ARRAY_APPROX_COUNT_DISTINCT([1, 1, 2, 3, 3, 3]) AS approx_cnt;

┌────────────┐
│ approx_cnt │
├────────────┤
│          3 │
└────────────┘

SELECT ARRAY_APPROX_COUNT_DISTINCT([NULL, 'a', 'a', 'b']) AS approx_cnt_text;

┌──────────────────┐
│ approx_cnt_text  │
├──────────────────┤
│                2 │
└──────────────────┘