HLL_COUNT_ESTIMATE

Extracts a cardinality estimate of a single HLL++ sketch that was previously built using the aggregate function HLL_COUNT_BUILD.

Syntax

HLL_COUNT_ESTIMATE(<expression>)

Parameter	Description	Supported input types
`<expression>`	An HLL++ sketch produced by the HLL_COUNT_BUILD function.	`BYTEA`

BIGINT

SELECT hll_count_estimate(a) AS hll_estimate
FROM sketch_of_data_to_count
ORDER BY 1;

hll_estimate (BIGINT)
3291008
4948957

SELECT hll_count_estimate(hll_count_merge(a)) AS hll_estimate
FROM sketch_of_data_to_count;

hll_estimate (BIGINT)
6606880

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