num_vals()

Get the number of values contained in a tdigest

Since 1.0.0

Get the number of values contained in a tdigest aggregate. This accessor allows you to calculate a count alongside percentiles, without needing to create two separate aggregates from the same raw data.

num_vals(
  digest TDigest
) RETURNS DOUBLE PRECISION

Arguments

Name	Type	Default	Required	Description
digest	TDigest	-		The tdigest aggregate to extract the number of values from

Returns

Column	Type	Description
num_vals	DOUBLE PRECISION	The number of values in the tdigest aggregate

Samples

Count the number of integers from 0 to 100.

SELECT num_vals(tdigest(data))
FROM generate_series(0, 100) data;

num_vals
-----------
    101