mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-09-20 16:50:48 +00:00
56 lines
1.9 KiB
Markdown
56 lines
1.9 KiB
Markdown
|
---
|
|||
|
|
toc_priority: 202
|
|||
|
|
---
|
|||
|
|
|
|||
|
|
# quantileExact {#quantileexact}
|
|||
|
|
|
|||
|
|
Exactly computes the [quantile](https://en.wikipedia.org/wiki/Quantile) of a numeric data sequence.
|
|||
|
|
|
|||
|
|
To get exact value, all the passed values are combined into an array, which is then partially sorted. Therefore, the function consumes `O(n)` memory, where `n` is a number of values that were passed. However, for a small number of values, the function is very effective.
|
|||
|
|
|
|||
|
|
When using multiple `quantile*` functions with different levels in a query, the internal states are not combined (that is, the query works less efficiently than it could). In this case, use the [quantiles](quantiles.md#quantiles) function.
|
|||
|
|
|
|||
|
|
**Syntax**
|
|||
|
|
|
|||
|
|
``` sql
|
|||
|
|
quantileExact(level)(expr)
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
Alias: `medianExact`.
|
|||
|
|
|
|||
|
|
**Parameters**
|
|||
|
|
|
|||
|
|
- `level` — Level of quantile. Optional parameter. Constant floating-point number from 0 to 1. We recommend using a `level` value in the range of `[0.01, 0.99]`. Default value: 0.5. At `level=0.5` the function calculates [median](https://en.wikipedia.org/wiki/Median).
|
|||
|
|
- `expr` — Expression over the column values resulting in numeric [data types](../../../sql-reference/data-types/index.md#data_types), [Date](../../../sql-reference/data-types/date.md) or [DateTime](../../../sql-reference/data-types/datetime.md).
|
|||
|
|
|
|||
|
|
**Returned value**
|
|||
|
|
|
|||
|
|
- Quantile of the specified level.
|
|||
|
|
|
|||
|
|
Type:
|
|||
|
|
|
|||
|
|
- [Float64](../../../sql-reference/data-types/float.md) for numeric data type input.
|
|||
|
|
- [Date](../../../sql-reference/data-types/date.md) if input values have the `Date` type.
|
|||
|
|
- [DateTime](../../../sql-reference/data-types/datetime.md) if input values have the `DateTime` type.
|
|||
|
|
|
|||
|
|
**Example**
|
|||
|
|
|
|||
|
|
Query:
|
|||
|
|
|
|||
|
|
``` sql
|
|||
|
|
SELECT quantileExact(number) FROM numbers(10)
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
Result:
|
|||
|
|
|
|||
|
|
``` text
|
|||
|
|
┌─quantileExact(number)─┐
|
|||
|
|
│ 5 │
|
|||
|
|
└───────────────────────┘
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**See Also**
|
|||
|
|
|
|||
|
|
- [median](median.md#median)
|
|||
|
|
- [quantiles](quantiles.md#quantiles)
|