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#
- merge(tdigest) tdigest
Aggregates all inputs into a single
tdigest
.
- value_at_quantile(tdigest, quantile) double
Returns the approximate percentile value from the T-digest, given the number
quantile
between 0 and 1.
- values_at_quantiles(tdigest, quantiles)
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.
- tdigest_agg(x) tdigest #
Composes all input values of
x
into atdigest
.x
can be of any numeric type.
- tdigest_agg(x, w) tdigest
Composes all input values of
x
into atdigest
using the per-item weightw
.w
must be greater or equal than 1.x
andw
can be of any numeric type.