T-Digest functions

Data structures

A T-digest is a data sketch which stores approximate percentile information. The Trino type for this data structure is called tdigest. T-digests can be merged, and for storage and retrieval they can be cast to and from VARBINARY.

Functions

:::{function} merge(tdigest) -> tdigest :noindex: true

Aggregates all inputs into a single tdigest. :::

:::{function} value_at_quantile(tdigest, quantile) -> double :noindex: true

Returns the approximate percentile value from the T-digest, given the number quantile between 0 and 1. :::

:::{function} values_at_quantiles(tdigest, quantiles) -> array(double) :noindex: true

Returns the approximate percentile values as an array, given the input T-digest and an array of values between 0 and 1, which represent the quantiles to return. :::

:::{function} tdigest_agg(x) -> tdigest Composes all input values of x into a tdigest. x can be of any numeric type. :::

:::{function} tdigest_agg(x, w) -> tdigest :noindex: true

Composes all input values of x into a tdigest using the per-item weight w. w must be greater or equal than 1. x and w can be of any numeric type. :::