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APPROX_COUNT_DISTINCT_COMBINE
An aggregate function. Merges two or more HyperLogLog states into a new state and returns a value of type VARBINARY(16384) representing the new state.
Syntax
APPROX_COUNT_DISTINCT_COMBINE ( expr )
Arguments
expr
An expression evaluating to a scalar value of type VARBINARY(16384).
expr is typically the name of a column. In this case, APPROX_COUNT_DISTINCT_COMBINE uses values in the column (which are HyperLogLog states) to create a new state.
Remarks
This function is used in conjuction with APPROX_COUNT_DISTINCT_ACCUMULATE and APPROX_COUNT_DISTINCT_ESTIMATE. To best understand its usage, see the topic Distinct Count Estimation Functions.
