> ## 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.

# Approximate Aggregate Functions

## `approx_count_distinct`

*Supported Signatures*

```sql theme={null}
function approx_count_distinct($1) returns bigint
```

[🔗 Official Documentation](https://cloud.google.com/bigquery/docs/reference/standard-sql/functions-and-operators#approx_count_distinct)

## `approx_quantiles`

*Supported Signatures*

```sql theme={null}
function approx_quantiles($1, bigint) returns array<$1>
```

[🔗 Official Documentation](https://cloud.google.com/bigquery/docs/reference/standard-sql/functions-and-operators#approx_quantiles)

## `approx_top_count`

*Supported Signatures*

```sql theme={null}
function approx_top_count($1, bigint) returns array<struct<value $1, count bigint>>
```

[🔗 Official Documentation](https://cloud.google.com/bigquery/docs/reference/standard-sql/functions-and-operators#approx_top_count)

## `approx_top_sum`

*Supported Signatures*

```sql theme={null}
function approx_top_sum($1, bigint, bigint) returns array<struct<value $1, sum $1>>
```

[🔗 Official Documentation](https://cloud.google.com/bigquery/docs/reference/standard-sql/functions-and-operators#approx_top_sum)