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> Returns an array of the approximately most frequent values and their counts in the specified column.

# approx_top_k

<h2 id="approx_top_k">
  approx\_top\_k
</h2>

Introduced in: v1.1.0

Returns an array of the approximately most frequent values and their counts in the specified column.
The resulting array is sorted in descending order of approximate frequency of values (not by the values themselves).

This function does not provide a guaranteed result.
In certain situations, errors might occur and it might return frequent values that aren't the most frequent values.

**Syntax**

```sql theme={null}
approx_top_k(N[, reserved])(column)
```

**Aliases**: `approx_top_count`

**Parameters**

* `N` — The number of elements to return. Default value: `10`. Maximum value of `N = 65536`. [`UInt64`](/reference/data-types/int-uint)
* `reserved` — Optional. Defines how many cells reserved for values. If `uniq(column) > reserved`, the result will be approximate. Default value: `N * 3`. [`UInt64`](/reference/data-types/int-uint)

**Arguments**

* `column` — The name of the column for which to find the most frequent values. [`String`](/reference/data-types/string)

**Returned value**

Returns an array of the approximately most frequent values and their counts, sorted in descending order of approximate frequency. [`Array`](/reference/data-types/array)

**Examples**

**Usage example**

```sql title=Query theme={null}
SELECT approx_top_k(2)(k)
FROM VALUES('k Char, w UInt64', ('y', 1), ('y', 1), ('x', 5), ('y', 1), ('z', 10));
```

```response title=Response theme={null}
┌─approx_top_k(2)(k)────┐
│ [('y',3,0),('x',1,0)] │
└───────────────────────┘
```

**See Also**

* [topK](/reference/functions/aggregate-functions/topK)
* [topKWeighted](/reference/functions/aggregate-functions/topKWeighted)
* [approx\_top\_sum](/reference/functions/aggregate-functions/approxtopsum)