quantileExact | RawTree

Exactly computes the 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 function.

Syntax

quantileExact(level)(expr)

Parameters

level — Optional. Level of quantile. 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. Float*

Arguments

expr — Expression over the column values resulting in numeric data types, Date or DateTime. (U)Int* or Float* or Decimal* or Date or DateTime

Returned value

Quantile of the specified level. For numeric data types the output format will be the same as the input format. (U)Int* or Float* or Decimal* or Date or DateTime

Examples

Computing exact quantile

SELECT quantileExact(number) FROM numbers(10);

┌─quantileExact(number)─┐
│                     5 │
└───────────────────────┘

Introduced in version 1.1.