> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sdf.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Qdigest Functions

## `qdigest_agg`

Returns the qdigest which is composed of  all input values of x.

*Supported Signatures*

```sql theme={null}
function qdigest_agg(bigint) returns qdigest
function qdigest_agg(bigint, bigint) returns qdigest
function qdigest_agg(bigint, bigint, double) returns qdigest
function qdigest_agg(double) returns qdigest
function qdigest_agg(double, bigint) returns qdigest
function qdigest_agg(double, bigint, double) returns qdigest
function qdigest_agg(real) returns qdigest
function qdigest_agg(real, bigint) returns qdigest
function qdigest_agg(real, bigint, double) returns qdigest
```

[🔗 Official Documentation](https://trino.io/docs/current/functions/qdigest.html#qdigest_agg)

## `quantile_at_value`

Returns the approximate quantile number between 0 and 1 from the quantile digest given an input value. Null is returned if the quantile digest is empty or the input value is outside of the range of the quantile digest.

*Supported Signatures*

```sql theme={null}
function quantile_at_value(qdigest, bigint) returns double
function quantile_at_value(qdigest, double) returns double
function quantile_at_value(qdigest, real) returns double
```

[🔗 Official Documentation](https://trino.io/docs/current/functions/qdigest.html#quantile_at_value)

## `value_at_quantile`

Returns the approximate percentile value from the quantile digest given the number quantile between 0 and 1.

*Supported Signatures*

```sql theme={null}
function value_at_quantile(qdigest, double) returns bigint
function value_at_quantile(tdigest, double) returns double
```

[🔗 Official Documentation](https://trino.io/docs/current/functions/qdigest.html#value_at_quantile)

## `values_at_quantiles`

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

*Supported Signatures*

```sql theme={null}
function values_at_quantiles(qdigest, array<double>) returns array<bigint>
function values_at_quantiles(tdigest, array<double>) returns array<double>
```

[🔗 Official Documentation](https://trino.io/docs/current/functions/qdigest.html#values_at_quantiles)