Arrays

array

Creates an array from the function arguments.

The arguments should be constants and have types that share a common supertype. At least one argument must be passed, because otherwise it isn't clear which type of array to create. This means that you can't use this function to create an empty array. To do so, use the emptyArray* function.

Use the [ ] operator for the same functionality.

Syntax

array(x1 [, x2, ..., xN])

Arguments

• x1 — Constant value of any type T. If only this argument is provided, the array will be of type T. - [, x2, ..., xN] — Additional N constant values sharing a common supertype with x1

Returned value

Returns an array, where 'T' is the smallest common type out of the passed arguments. Array(T)

Examples

Valid usage

SELECT array(toInt32(1), toUInt16(2), toInt8(3)) AS a, toTypeName(a)

┌─a───────┬─toTypeName(a)─┐
│ [1,2,3] │ Array(Int32)  │
└─────────┴───────────────┘

Invalid usage

SELECT array(toInt32(5), toDateTime('1998-06-16'), toInt8(5)) AS a, toTypeName(a)

Received exception from server (version 25.4.3):
Code: 386. DB::Exception: Received from localhost:9000. DB::Exception:
There is no supertype for types Int32, DateTime, Int8 ...

Introduced in version 1.1.

arrayAUCPR

Calculates the area under the precision-recall (PR) curve. A precision-recall curve is created by plotting precision on the y-axis and recall on the x-axis across all thresholds. The resulting value ranges from 0 to 1, with a higher value indicating better model performance. The PR AUC is particularly useful for imbalanced datasets, providing a clearer comparison of performance compared to ROC AUC on those cases. For more details, please see here, here and here.

Syntax

arrayAUCPR(scores, labels[, partial_offsets])

Arguments

• cores — Scores prediction model gives. Array((U)Int*) or Array(Float*)
• labels — Labels of samples, usually 1 for positive sample and 0 for negative sample. Array((U)Int*) or Array(Enum)
• partial_offsets —
• Optional. An Array(T) of three non-negative integers for calculating a partial area under the PR curve (equivalent to a vertical band of the PR space) instead of the whole AUC. This option is useful for distributed computation of the PR AUC. The array must contain the following elements [higher_partitions_tp, higher_partitions_fp, total_positives].
  • higher_partitions_tp: The number of positive labels in the higher-scored partitions.
  • higher_partitions_fp: The number of negative labels in the higher-scored partitions.
  • total_positives: The total number of positive samples in the entire dataset.

:::note When arr_partial_offsets is used, the arr_scores and arr_labels should be only a partition of the entire dataset, containing an interval of scores. The dataset should be divided into contiguous partitions, where each partition contains the subset of the data whose scores fall within a specific range. For example:

• One partition could contain all scores in the range [0, 0.5).
• Another partition could contain scores in the range [0.5, 1.0]. :::

Returned value

Returns area under the precision-recall (PR) curve. Float64

Examples

Usage example

SELECT arrayAUCPR([0.1, 0.4, 0.35, 0.8], [0, 0, 1, 1]);

┌─arrayAUCPR([0.1, 0.4, 0.35, 0.8], [0, 0, 1, 1])─┐
│                              0.8333333333333333 │
└─────────────────────────────────────────────────┘

Introduced in version 20.4.

arrayAll

Returns 1 if lambda func(x [, y1, y2, ... yN]) returns true for all elements. Otherwise, it returns 0.

Syntax

arrayAll(func(x[, y1, ..., yN]), source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Array(T)
• cond1_arr, ... — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns 1 if the lambda function returns true for all elements, 0 otherwise UInt8

Examples

All elements match

SELECT arrayAll(x, y -> x=y, [1, 2, 3], [1, 2, 3])

1

Not all elements match

SELECT arrayAll(x, y -> x=y, [1, 2, 3], [1, 1, 1])

0

Introduced in version 1.1.

arrayAvg

Returns the average of elements in the source array.

If a lambda function func is specified, returns the average of elements of the lambda results.

Syntax

arrayAvg([func(x[, y1, ..., yN])], source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — Optional. A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Array(T)
• [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns the average of elements in the source array, or the average of elements of the lambda results if provided. Float64

Examples

Basic example

SELECT arrayAvg([1, 2, 3, 4]);

2.5

Usage with lambda function

SELECT arrayAvg(x, y -> x*y, [2, 3], [2, 3]) AS res;

6.5

Introduced in version 21.1.

arrayCompact

Removes consecutive duplicate elements from an array, including null values. The order of values in the resulting array is determined by the order in the source array.

Syntax

arrayCompact(arr)

Arguments

• arr — An array to remove duplicates from. Array(T)

Returned value

Returns an array without duplicate values Array(T)

Examples

Usage example

SELECT arrayCompact([1, 1, nan, nan, 2, 3, 3, 3]);

[1,nan,2,3]

Introduced in version 20.1.

arrayConcat

Combines arrays passed as arguments.

Syntax

arrayConcat(arr1 [, arr2, ... , arrN])

Arguments

• arr1 [, arr2, ... , arrN] — N number of arrays to concatenate. Array(T)

Returned value

Returns a single combined array from the provided array arguments. Array(T)

Examples

Usage example

SELECT arrayConcat([1, 2], [3, 4], [5, 6]) AS res

[1, 2, 3, 4, 5, 6]

Introduced in version 1.1.

arrayCount

Returns the number of elements for which func(arr1[i], ..., arrN[i]) returns true. If func is not specified, it returns the number of non-zero elements in the array.

arrayCount is a higher-order function.

Syntax

arrayCount([func, ] arr1, ...)

Arguments

• func — Optional. Function to apply to each element of the array(s). Lambda function
• arr1, ..., arrN — N arrays. Array(T)

Returned value

Returns the number of elements for which func returns true. Otherwise, returns the number of non-zero elements in the array. UInt32

Examples

Usage example

SELECT arrayCount(x -> (x % 2), groupArray(number)) FROM numbers(10)

5

Introduced in version 1.1.

arrayCumSum

Returns an array of the partial (running) sums of the elements in the source array. If a lambda function is specified, the sum is computed from applying the lambda to the array elements at each position.

Syntax

arrayCumSum([func,] arr1[, arr2, ... , arrN])

Arguments

• func — Optional. A lambda function to apply to the array elements at each position. Lambda function
• arr1 — The source array of numeric values. Array(T)
• [arr2, ..., arrN] — Optional. Additional arrays of the same size, passed as arguments to the lambda function if specified. Array(T)

Returned value

Returns an array of the partial sums of the elements in the source array. The result type matches the input array's numeric type. Array(T)

Examples

Basic usage

SELECT arrayCumSum([1, 1, 1, 1]) AS res

[1, 2, 3, 4]

With lambda

SELECT arrayCumSum(x -> x * 2, [1, 2, 3]) AS res

[2, 6, 12]

Introduced in version 1.1.

arrayCumSumNonNegative

Returns an array of the partial (running) sums of the elements in the source array, replacing any negative running sum with zero. If a lambda function is specified, the sum is computed from applying the lambda to the array elements at each position.

Syntax

arrayCumSumNonNegative([func,] arr1[, arr2, ... , arrN])

Arguments

• func — Optional. A lambda function to apply to the array elements at each position. Lambda function
• arr1 — The source array of numeric values. Array(T)
• [arr2, ..., arrN] — Optional. Additional arrays of the same size, passed as arguments to the lambda function if specified. Array(T)

Returned value

Returns an array of the partial sums of the elements in the source array, with any negative running sum replaced by zero. The result type matches the input array's numeric type. Array(T)

Examples

Basic usage

SELECT arrayCumSumNonNegative([1, 1, -4, 1]) AS res

[1, 2, 0, 1]

With lambda

SELECT arrayCumSumNonNegative(x -> x * 2, [1, -2, 3]) AS res

[2, 0, 6]

Introduced in version 18.12.

arrayDifference

Calculates an array of differences between adjacent array elements. The first element of the result array will be 0, the second arr[1] - arr[0], the third arr[2] - arr[1], etc. The type of elements in the result array are determined by the type inference rules for subtraction (e.g. UInt8 - UInt8 = Int16).

Syntax

arrayDifference(arr)

Arguments

• arr — Array for which to calculate differences between adjacent elements. Array(T)

Returned value

Returns an array of differences between adjacent array elements UInt*

Examples

Usage example

SELECT arrayDifference([1, 2, 3, 4]);

[0,1,1,1]

Example of overflow due to result type Int64

SELECT arrayDifference([0, 10000000000000000000]);

┌─arrayDifference([0, 10000000000000000000])─┐
│ [0,-8446744073709551616]                   │
└────────────────────────────────────────────┘

Introduced in version 1.1.

arrayDistinct

Returns an array containing only the distinct elements of an array.

Syntax

arrayDistinct(arr)

Arguments

• arr — Array for which to extract distinct elements. Array(T)

Returned value

Returns an array containing the distinct elements Array(T)

Examples

Usage example

SELECT arrayDistinct([1, 2, 2, 3, 1]);

[1,2,3]

Introduced in version 1.1.

arrayDotProduct

Returns the dot product of two arrays.

:::note The sizes of the two vectors must be equal. Arrays and Tuples may also contain mixed element types. :::

Syntax

arrayDotProduct(v1, v2)

Arguments

• v1 — First vector. Array((U)Int* | Float* | Decimal) or Tuple((U)Int* | Float* | Decimal)
• v2 — Second vector. Array((U)Int* | Float* | Decimal) or Tuple((U)Int* | Float* | Decimal)

Returned value

The dot product of the two vectors.

:::note The return type is determined by the type of the arguments. If Arrays or Tuples contain mixed element types then the result type is the supertype. :::

(U)Int* or Float* or Decimal

Examples

Array example

SELECT arrayDotProduct([1, 2, 3], [4, 5, 6]) AS res, toTypeName(res);

32    UInt16

Tuple example

SELECT dotProduct((1::UInt16, 2::UInt8, 3::Float32),(4::Int16, 5::Float32, 6::UInt8)) AS res, toTypeName(res);

32    Float64

Introduced in version 23.5.

arrayElement

Gets the element of the provided array with index n where n can be any integer type. If the index falls outside of the bounds of an array, it returns a default value (0 for numbers, an empty string for strings, etc.), except for arguments of a non-constant array and a constant index 0. In this case there will be an error Array indices are 1-based.

:::note Arrays in RawTree are one-indexed. :::

Negative indexes are supported. In this case, the corresponding element is selected, numbered from the end. For example, arr[-1] is the last item in the array.

Operator [n] provides the same functionality.

Syntax

arrayElement(arr, n)

Arguments

• arr — The array to search. Array(T). - n — Position of the element to get. (U)Int*.

Returned value

Returns a single combined array from the provided array arguments Array(T)

Examples

Usage example

SELECT arrayElement(arr, 2) FROM (SELECT [1, 2, 3] AS arr)

2

Negative indexing

SELECT arrayElement(arr, -1) FROM (SELECT [1, 2, 3] AS arr)

3

Using [n] notation

SELECT arr[2] FROM (SELECT [1, 2, 3] AS arr)

2

Index out of array bounds

SELECT arrayElement(arr, 4) FROM (SELECT [1, 2, 3] AS arr)

0

Introduced in version 1.1.

arrayElementOrNull

Gets the element of the provided array with index n where n can be any integer type. If the index falls outside of the bounds of an array, NULL is returned instead of a default value.

:::note Arrays in RawTree are one-indexed. :::

Negative indexes are supported. In this case, it selects the corresponding element numbered from the end. For example, arr[-1] is the last item in the array.

Syntax

arrayElementOrNull(arrays)

Arguments

• arrays — Arbitrary number of array arguments. Array

Returned value

Returns a single combined array from the provided array arguments. Array(T)

Examples

Usage example

SELECT arrayElementOrNull(arr, 2) FROM (SELECT [1, 2, 3] AS arr)

2

Negative indexing

SELECT arrayElementOrNull(arr, -1) FROM (SELECT [1, 2, 3] AS arr)

3

Index out of array bounds

SELECT arrayElementOrNull(arr, 4) FROM (SELECT [1, 2, 3] AS arr)

NULL

Introduced in version 1.1.

arrayEnumerate

Returns the array [1, 2, 3, ..., length (arr)]

This function is normally used with the ARRAY JOIN clause. It allows counting something just once for each array after applying ARRAY JOIN. This function can also be used in higher-order functions. For example, you can use it to get array indexes for elements that match a condition.

Syntax

arrayEnumerate(arr)

Arguments

• arr — The array to enumerate. Array

Returned value

Returns the array [1, 2, 3, ..., length (arr)]. Array(UInt32)

Examples

Basic example with ARRAY JOIN

CREATE TABLE test
(
    `id` UInt8,
    `tag` Array(String),
    `version` Array(String)
)
ENGINE = MergeTree
ORDER BY id;

INSERT INTO test VALUES (1, ['release-stable', 'dev', 'security'], ['2.4.0', '2.6.0-alpha', '2.4.0-sec1']);

SELECT
    id,
    tag,
    version,
    seq
FROM test
ARRAY JOIN
    tag,
    version,
    arrayEnumerate(tag) AS seq

┌─id─┬─tag────────────┬─version─────┬─seq─┐
│  1 │ release-stable │ 2.4.0       │   1 │
│  1 │ dev            │ 2.6.0-alpha │   2 │
│  1 │ security       │ 2.4.0-sec1  │   3 │
└────┴────────────────┴─────────────┴─────┘

Introduced in version 1.1.

arrayEnumerateDense

Returns an array of the same size as the source array, indicating where each element first appears in the source array.

Syntax

arrayEnumerateDense(arr)

Arguments

• arr — The array to enumerate. Array(T)

Returned value

Returns an array of the same size as arr, indicating where each element first appears in the source array Array(T)

Examples

Usage example

SELECT arrayEnumerateDense([10, 20, 10, 30])

[1,2,1,3]

Introduced in version 18.12.

arrayEnumerateDenseRanked

Returns an array the same size as the source array, indicating where each element first appears in the source array. It allows for enumeration of a multidimensional array with the ability to specify how deep to look inside the array.

Syntax

arrayEnumerateDenseRanked(clear_depth, arr, max_array_depth)

Arguments

• clear_depth — Enumerate elements at the specified level separately. Must be less than or equal to max_arr_depth. UInt*
• arr — N-dimensional array to enumerate. Array(T)
• max_array_depth — The maximum effective depth. Must be less than or equal to the depth of arr. UInt*

Returned value

Returns an array denoting where each element first appears in the source array Array

Examples

Basic usage

-- With clear_depth=1 and max_array_depth=1, the result is identical to what arrayEnumerateDense would give.

SELECT arrayEnumerateDenseRanked(1,[10, 20, 10, 30],1);

[1,2,1,3]

Usage with a multidimensional array

-- In this example, arrayEnumerateDenseRanked is used to obtain an array indicating, for each element of the
-- multidimensional array, what its position is among elements of the same value.
-- For the first row of the passed array, [10, 10, 30, 20], the corresponding first row of the result is [1, 1, 2, 3],
-- indicating that 10 is the first number encountered in position 1 and 2, 30 the second number encountered in position 3
-- and 20 is the third number encountered in position 4.
-- For the second row, [40, 50, 10, 30], the corresponding second row of the result is [4,5,1,2], indicating that 40
-- and 50 are the fourth and fifth numbers encountered in position 1 and 2 of that row, that another 10
-- (the first encountered number) is in position 3 and 30 (the second number encountered) is in the last position.

SELECT arrayEnumerateDenseRanked(1,[[10,10,30,20],[40,50,10,30]],2);

[[1,1,2,3],[4,5,1,2]]

Example with increased clear_depth

-- Changing clear_depth=2 results in the enumeration occurring separately for each row anew.

SELECT arrayEnumerateDenseRanked(2,[[10,10,30,20],[40,50,10,30]],2);

[[1, 1, 2, 3], [1, 2, 3, 4]]

Introduced in version 20.1.

arrayEnumerateUniq

Returns an array the same size as the source array, indicating for each element what its position is among elements with the same value.

This function is useful when using ARRAY JOIN and aggregation of array elements.

The function can take multiple arrays of the same size as arguments. In this case, uniqueness is considered for tuples of elements in the same positions in all the arrays.

Syntax

arrayEnumerateUniq(arr1[, arr2, ... , arrN])

Arguments

• arr1 — First array to process. Array(T)
• arr2, ... — Optional. Additional arrays of the same size for tuple uniqueness. Array(UInt32)

Returned value

Returns an array where each element is the position among elements with the same value or tuple. Array(T)

Examples

Basic usage

SELECT arrayEnumerateUniq([10, 20, 10, 30]);

[1, 1, 2, 1]

Multiple arrays

SELECT arrayEnumerateUniq([1, 1, 1, 2, 2, 2], [1, 1, 2, 1, 1, 2]);

[1,2,1,1,2,1]

ARRAY JOIN aggregation

-- Each goal ID has a calculation of the number of conversions (each element in the Goals nested data structure is a goal that was reached, which we refer to as a conversion)
-- and the number of sessions. Without ARRAY JOIN, we would have counted the number of sessions as sum(Sign). But in this particular case,
-- the rows were multiplied by the nested Goals structure, so in order to count each session one time after this, we apply a condition to the
-- value of the arrayEnumerateUniq(Goals.ID) function.

SELECT
    Goals.ID AS GoalID,
    sum(Sign) AS Reaches,
    sumIf(Sign, num = 1) AS Visits
FROM test.visits
ARRAY JOIN
    Goals,
    arrayEnumerateUniq(Goals.ID) AS num
WHERE CounterID = 160656
GROUP BY GoalID
ORDER BY Reaches DESC
LIMIT 10

┌──GoalID─┬─Reaches─┬─Visits─┐
│   53225 │    3214 │   1097 │
│ 2825062 │    3188 │   1097 │
│   56600 │    2803 │    488 │
│ 1989037 │    2401 │    365 │
│ 2830064 │    2396 │    910 │
│ 1113562 │    2372 │    373 │
│ 3270895 │    2262 │    812 │
│ 1084657 │    2262 │    345 │
│   56599 │    2260 │    799 │
│ 3271094 │    2256 │    812 │
└─────────┴─────────┴────────┘

Introduced in version 1.1.

arrayEnumerateUniqRanked

Returns an array (or multi-dimensional array) with the same dimensions as the source array, indicating for each element what it's position is among elements with the same value. It allows for enumeration of a multi-dimensional array with the ability to specify how deep to look inside the array.

Syntax

arrayEnumerateUniqRanked(clear_depth, arr, max_array_depth)

Arguments

• clear_depth — Enumerate elements at the specified level separately. Positive integer less than or equal to max_arr_depth. UInt*
• arr — N-dimensional array to enumerate. Array(T)
• max_array_depth — The maximum effective depth. Positive integer less than or equal to the depth of arr. UInt*

Returned value

Returns an N-dimensional array the same size as arr with each element showing the position of that element in relation to other elements of the same value. Array(T)

Examples

Example 1

-- With clear_depth=1 and max_array_depth=1, the result of arrayEnumerateUniqRanked
-- is identical to that which arrayEnumerateUniq would give for the same array.

SELECT arrayEnumerateUniqRanked(1, [1, 2, 1], 1);

[1, 1, 2]

Example 2

-- with clear_depth=1 and max_array_depth=1, the result of arrayEnumerateUniqRanked
-- is identical to that which arrayEnumerateUniqwould give for the same array.

SELECT arrayEnumerateUniqRanked(1, [[1, 2, 3], [2, 2, 1], [3]], 2);", "[[1, 1, 1], [2, 3, 2], [2]]

[1, 1, 2]

Example 3

-- In this example, arrayEnumerateUniqRanked is used to obtain an array indicating,
-- for each element of the multidimensional array, what its position is among elements
-- of the same value. For the first row of the passed array, [1, 2, 3], the corresponding
-- result is [1, 1, 1], indicating that this is the first time 1, 2 and 3 are encountered.
-- For the second row of the provided array, [2, 2, 1], the corresponding result is [2, 3, 3],
-- indicating that 2 is encountered for a second and third time, and 1 is encountered
-- for the second time. Likewise, for the third row of the provided array [3] the
-- corresponding result is [2] indicating that 3 is encountered for the second time.

SELECT arrayEnumerateUniqRanked(1, [[1, 2, 3], [2, 2, 1], [3]], 2);

[[1, 1, 1], [2, 3, 2], [2]]

Example 4

-- Changing clear_depth=2, results in elements being enumerated separately for each row.
SELECT arrayEnumerateUniqRanked(2,[[1, 2, 3],[2, 2, 1],[3]], 2);

[[1, 1, 1], [1, 2, 1], [1]]

Introduced in version 20.1.

arrayExcept

Returns an array containing elements from source that are not present in except, preserving the original order.

This function performs a set difference operation between two arrays. For each element in source, it checks if the element exists in except (using exact comparison). If not, the element is included in the result.

The operation maintains these properties:

1. Order of elements from source is preserved
2. Duplicates in source are preserved if they don't exist in except
3. NULL is handled as a separate value

Syntax

arrayExcept(source, except)

Arguments

• source — The source array containing elements to filter. Array(T)
• except — The array containing elements to exclude from the result. Array(T)

Returned value

Returns an array of the same type as the input array containing elements from source that weren't found in except. Array(T)

Examples

basic

SELECT arrayExcept([1, 2, 3, 2, 4], [3, 5])

[1, 2, 2, 4]

with_nulls1

SELECT arrayExcept([1, NULL, 2, NULL], [2])

[1, NULL, NULL]

with_nulls2

SELECT arrayExcept([1, NULL, 2, NULL], [NULL, 2, NULL])

[1]

strings

SELECT arrayExcept(['apple', 'banana', 'cherry'], ['banana', 'date'])

['apple', 'cherry']

Introduced in version 25.9.

arrayExists

Returns 1 if there is at least one element in a source array for which func(x[, y1, y2, ... yN]) returns true. Otherwise, it returns 0.

Syntax

arrayExists(func(x[, y1, ..., yN]), source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Array(T)
• [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns 1 if the lambda function returns true for at least one element, 0 otherwise UInt8

Examples

Usage example

SELECT arrayExists(x, y -> x=y, [1, 2, 3], [0, 0, 0])

0

Introduced in version 1.1.

arrayFill

The arrayFill function sequentially processes a source array from the first element to the last, evaluating a lambda condition at each position using elements from the source and condition arrays. When the lambda function evaluates to false at position i, the function replaces that element with the element at position i-1 from the current state of the array. The first element is always preserved regardless of any condition.

Syntax

arrayFill(func(x [, y1, ..., yN]), source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x [, y1, ..., yN]) — A lambda function func(x [, y1, y2, ... yN]) → F(x [, y1, y2, ... yN]) which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Lambda function
• [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns an array Array(T)

Examples

Example with single array

SELECT arrayFill(x -> not isNull(x), [1, null, 2, null]) AS res

[1, 1, 2, 2]

Example with two arrays

SELECT arrayFill(x, y, z -> x > y AND x < z, [5, 3, 6, 2], [4, 7, 1, 3], [10, 2, 8, 5]) AS res

[5, 5, 6, 6]

Introduced in version 20.1.

arrayFilter

Returns an array containing only the elements in the source array for which a lambda function returns true.

Syntax

arrayFilter(func(x[, y1, ..., yN]), source_arr[, cond1_arr, ... , condN_arr])]

Arguments

• func(x[, y1, ..., yN]) — A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Array(T)
• [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns a subset of the source array Array(T)

Examples

Example 1

SELECT arrayFilter(x -> x LIKE '%World%', ['Hello', 'abc World']) AS res

['abc World']

Example 2

SELECT
    arrayFilter(
        (i, x) -> x LIKE '%World%',
        arrayEnumerate(arr),
        ['Hello', 'abc World'] AS arr)
    AS res

[2]

Introduced in version 1.1.

arrayFirst

Returns the first element in the source array for which func(x[, y1, y2, ... yN]) returns true, otherwise it returns a default value.

Syntax

arrayFirst(func(x[, y1, ..., yN]), source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function. - source_arr — The source array to process. Array(T). - [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T).

Returned value

Returns the first element of the source array for which λ is true, otherwise returns the default value of T.

Examples

Usage example

SELECT arrayFirst(x, y -> x=y, ['a', 'b', 'c'], ['c', 'b', 'a'])

b

No match

SELECT arrayFirst(x, y -> x=y, [0, 1, 2], [3, 3, 3]) AS res, toTypeName(res)

0 UInt8

Introduced in version 1.1.

arrayFirstIndex

Returns the index of the first element in the source array for which func(x[, y1, y2, ... yN]) returns true, otherwise it returns '0'.

Syntax

arrayFirstIndex(func(x[, y1, ..., yN]), source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function. - source_arr — The source array to process. Array(T). - [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T).

Returned value

Returns the index of the first element of the source array for which func is true, otherwise returns 0 UInt32

Examples

Usage example

SELECT arrayFirstIndex(x, y -> x=y, ['a', 'b', 'c'], ['c', 'b', 'a'])

2

No match

SELECT arrayFirstIndex(x, y -> x=y, ['a', 'b', 'c'], ['d', 'e', 'f'])

0

Introduced in version 1.1.

arrayFirstOrNull

Returns the first element in the source array for which func(x[, y1, y2, ... yN]) returns true, otherwise it returns NULL.

Syntax

arrayFirstOrNull(func(x[, y1, ..., yN]), source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Array(T)
• [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns the first element of the source array for which func is true, otherwise returns NULL.

Examples

Usage example

SELECT arrayFirstOrNull(x, y -> x=y, ['a', 'b', 'c'], ['c', 'b', 'a'])

b

No match

SELECT arrayFirstOrNull(x, y -> x=y, [0, 1, 2], [3, 3, 3]) AS res, toTypeName(res)

NULL Nullable(UInt8)

Introduced in version 1.1.

arrayFlatten

Converts an array of arrays to a flat array.

Function:

• Applies to any depth of nested arrays.
• Does not change arrays that are already flat.

The flattened array contains all the elements from all source arrays.

Syntax

arrayFlatten(arr)

Arguments

• arr — A multidimensional array. Array(Array(T))

Returned value

Returns a flattened array from the multidimensional array Array(T)

Examples

Usage example

SELECT arrayFlatten([[[1]], [[2], [3]]]);

[1, 2, 3]

Introduced in version 20.1.

arrayFold

Applies a lambda function to one or more equally-sized arrays and collects the result in an accumulator.

Syntax

arrayFold(λ(acc, x1 [, x2, x3, ... xN]), arr1 [, arr2, arr3, ... arrN], acc)

Arguments

• λ(x, x1 [, x2, x3, ... xN]) — A lambda function λ(acc, x1 [, x2, x3, ... xN]) → F(acc, x1 [, x2, x3, ... xN]) where F is an operation applied to acc and array values from x with the result of acc re-used. Lambda function
• arr1 [, arr2, arr3, ... arrN] — N arrays over which to operate. Array(T)
• acc — Accumulator value with the same type as the return type of the Lambda function.

Returned value

Returns the final acc value.

Examples

Usage example

SELECT arrayFold(acc,x -> acc + x*2, [1, 2, 3, 4], 3::Int64) AS res;

23

Fibonacci sequence

SELECT arrayFold(acc, x -> (acc.2, acc.2 + acc.1),range(number),(1::Int64, 0::Int64)).1 AS fibonacci FROM numbers(1,10);

┌─fibonacci─┐
│         0 │
│         1 │
│         1 │
│         2 │
│         3 │
│         5 │
│         8 │
│        13 │
│        21 │
│        34 │
└───────────┘

Example using multiple arrays

SELECT arrayFold(
(acc, x, y) -> acc + (x * y),
[1, 2, 3, 4],
[10, 20, 30, 40],
0::Int64
) AS res;

300

Introduced in version 23.10.

arrayIntersect

Takes multiple arrays and returns an array with elements which are present in all source arrays. The result contains only unique values.

Syntax

arrayIntersect(arr, arr1, ..., arrN)

Arguments

• arrN — N arrays from which to make the new array. Array(T).

Returned value

Returns an array with distinct elements that are present in all N arrays Array(T)

Examples

Usage example

SELECT
arrayIntersect([1, 2], [1, 3], [2, 3]) AS empty_intersection,
arrayIntersect([1, 2], [1, 3], [1, 4]) AS non_empty_intersection

┌─non_empty_intersection─┬─empty_intersection─┐
│ []                     │ [1]                │
└────────────────────────┴────────────────────┘

Introduced in version 1.1.

arrayJaccardIndex

Returns the Jaccard index of two arrays.

Syntax

arrayJaccardIndex(arr_x, arr_y)

Arguments

• arr_x — First array. Array(T)
• arr_y — Second array. Array(T)

Returned value

Returns the Jaccard index of arr_x and arr_y Float64

Examples

Usage example

SELECT arrayJaccardIndex([1, 2], [2, 3]) AS res

0.3333333333333333

Introduced in version 23.7.

arrayJoin

The arrayJoin function takes a row that contains an array and unfolds it, generating multiple rows – one for each element in the array. This is in contrast to Regular Functions in RawTree which map input values to output values within the same row, and Aggregate Functions which take a group of rows and "compress" or "reduce" them into a single summary row (or a single value within a summary row if used with GROUP BY).

All the values in the columns are simply copied, except the values in the column where this function is applied; these are replaced with the corresponding array value.

Syntax

arrayJoin(arr)

Arguments

• arr — An array to unfold. Array(T)

Returned value

Returns a set of rows unfolded from arr.

Examples

Basic usage

SELECT arrayJoin([1, 2, 3] AS src) AS dst, 'Hello', src

┌─dst─┬─\'Hello\'─┬─src─────┐
│   1 │ Hello     │ [1,2,3] │
│   2 │ Hello     │ [1,2,3] │
│   3 │ Hello     │ [1,2,3] │
└─────┴───────────┴─────────┘

arrayJoin affects all sections of the query

-- The arrayJoin function affects all sections of the query, including the WHERE section. Notice the result 2, even though the subquery returned 1 row.

SELECT sum(1) AS impressions
FROM
(
    SELECT ['Istanbul', 'Berlin', 'Bobruisk'] AS cities
)
WHERE arrayJoin(cities) IN ['Istanbul', 'Berlin'];

┌─impressions─┐
│           2 │
└─────────────┘

Using multiple arrayJoin functions

- A query can use multiple arrayJoin functions. In this case, the transformation is performed multiple times and the rows are multiplied.

SELECT
    sum(1) AS impressions,
    arrayJoin(cities) AS city,
    arrayJoin(browsers) AS browser
FROM
(
    SELECT
        ['Istanbul', 'Berlin', 'Bobruisk'] AS cities,
        ['Firefox', 'Chrome', 'Chrome'] AS browsers
)
GROUP BY
    2,
    3

┌─impressions─┬─city─────┬─browser─┐
│           2 │ Istanbul │ Chrome  │
│           1 │ Istanbul │ Firefox │
│           2 │ Berlin   │ Chrome  │
│           1 │ Berlin   │ Firefox │
│           2 │ Bobruisk │ Chrome  │
│           1 │ Bobruisk │ Firefox │
└─────────────┴──────────┴─────────┘

Unexpected results due to optimizations

-- Using multiple arrayJoin with the same expression may not produce the expected result due to optimizations.
-- For these cases, consider modifying the repeated array expression with extra operations that do not affect join result.
- e.g. arrayJoin(arraySort(arr)), arrayJoin(arrayConcat(arr, []))

SELECT
    arrayJoin(dice) as first_throw,
    /* arrayJoin(dice) as second_throw */ -- is technically correct, but will annihilate result set
    arrayJoin(arrayConcat(dice, [])) as second_throw -- intentionally changed expression to force re-evaluation
FROM (
    SELECT [1, 2, 3, 4, 5, 6] as dice
);

┌─first_throw─┬─second_throw─┐
│           1 │            1 │
│           1 │            2 │
│           1 │            3 │
│           1 │            4 │
│           1 │            5 │
│           1 │            6 │
│           2 │            1 │
│           2 │            2 │
│           2 │            3 │
│           2 │            4 │
│           2 │            5 │
│           2 │            6 │
│           3 │            1 │
│           3 │            2 │
│           3 │            3 │
│           3 │            4 │
│           3 │            5 │
│           3 │            6 │
│           4 │            1 │
│           4 │            2 │
│           4 │            3 │
│           4 │            4 │
│           4 │            5 │
│           4 │            6 │
│           5 │            1 │
│           5 │            2 │
│           5 │            3 │
│           5 │            4 │
│           5 │            5 │
│           5 │            6 │
│           6 │            1 │
│           6 │            2 │
│           6 │            3 │
│           6 │            4 │
│           6 │            5 │
│           6 │            6 │
└─────────────┴──────────────┘

Using the ARRAY JOIN syntax

-- Note the ARRAY JOIN syntax in the `SELECT` query below, which provides broader possibilities.
-- ARRAY JOIN allows you to convert multiple arrays with the same number of elements at a time.

SELECT
    sum(1) AS impressions,
    city,
    browser
FROM
(
    SELECT
        ['Istanbul', 'Berlin', 'Bobruisk'] AS cities,
        ['Firefox', 'Chrome', 'Chrome'] AS browsers
)
ARRAY JOIN
    cities AS city,
    browsers AS browser
GROUP BY
    2,
    3

┌─impressions─┬─city─────┬─browser─┐
│           1 │ Istanbul │ Firefox │
│           1 │ Berlin   │ Chrome  │
│           1 │ Bobruisk │ Chrome  │
└─────────────┴──────────┴─────────┘

Using Tuple

-- You can also use Tuple

SELECT
    sum(1) AS impressions,
    (arrayJoin(arrayZip(cities, browsers)) AS t).1 AS city,
    t.2 AS browser
FROM
(
    SELECT
        ['Istanbul', 'Berlin', 'Bobruisk'] AS cities,
        ['Firefox', 'Chrome', 'Chrome'] AS browsers
)
GROUP BY
    2,
    3

┌─impressions─┬─city─────┬─browser─┐
│           1 │ Istanbul │ Firefox │
│           1 │ Berlin   │ Chrome  │
│           1 │ Bobruisk │ Chrome  │
└─────────────┴──────────┴─────────┘

Introduced in version 1.1.

arrayLast

Returns the last element in the source array for which a lambda func(x [, y1, y2, ... yN]) returns true, otherwise it returns a default value.

Syntax

arrayLast(func(x[, y1, ..., yN]), source[, cond1, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function. - source — The source array to process. Array(T). - [, cond1, ... , condN] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T).

Returned value

Returns the last element of the source array for which func is true, otherwise returns the default value of T.

Examples

Usage example

SELECT arrayLast(x, y -> x=y, ['a', 'b', 'c'], ['a', 'b', 'c'])

c

No match

SELECT arrayFirst(x, y -> x=y, [0, 1, 2], [3, 3, 3]) AS res, toTypeName(res)

0 UInt8

Introduced in version 1.1.

arrayLastIndex

Returns the index of the last element in the source array for which func(x[, y1, y2, ... yN]) returns true, otherwise it returns '0'.

Syntax

arrayLastIndex(func(x[, y1, ..., yN]), source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Array(T)
• [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns the index of the last element of the source array for which func is true, otherwise returns 0 UInt32

Examples

Usage example

SELECT arrayLastIndex(x, y -> x=y, ['a', 'b', 'c'], ['a', 'b', 'c']);

3

No match

SELECT arrayLastIndex(x, y -> x=y, ['a', 'b', 'c'], ['d', 'e', 'f']);

0

Introduced in version 1.1.

arrayLastOrNull

Returns the last element in the source array for which a lambda func(x [, y1, y2, ... yN]) returns true, otherwise it returns NULL.

Syntax

arrayLastOrNull(func(x[, y1, ..., yN]), source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x [, y1, ..., yN]) — A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function. - source_arr — The source array to process. Array(T). - [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T).

Returned value

Returns the last element of the source array for which λ is not true, otherwise returns NULL.

Examples

Usage example

SELECT arrayLastOrNull(x, y -> x=y, ['a', 'b', 'c'], ['a', 'b', 'c'])

c

No match

SELECT arrayLastOrNull(x, y -> x=y, [0, 1, 2], [3, 3, 3]) AS res, toTypeName(res)

NULL Nullable(UInt8)

Introduced in version 1.1.

arrayLevenshteinDistance

Calculates the Levenshtein distance for two arrays.

Syntax

arrayLevenshteinDistance(from, to)

Arguments

• from — The first array. Array(T). - to — The second array. Array(T).

Returned value

Levenshtein distance between the first and the second arrays. Float64

Examples

Usage example

SELECT arrayLevenshteinDistance([1, 2, 4], [1, 2, 3])

1

Introduced in version 25.4.

arrayLevenshteinDistanceWeighted

Calculates Levenshtein distance for two arrays with custom weights for each element. The number of elements for the array and its weights should match.

Syntax

arrayLevenshteinDistanceWeighted(from, to, from_weights, to_weights)

Arguments

• from — first array. Array(T). - to — second array. Array(T). - from_weights — weights for the first array. Array((U)Int*|Float*)
• to_weights — weights for the second array. Array((U)Int*|Float*)

Returned value

Levenshtein distance between the first and the second arrays with custom weights for each element Float64

Examples

Usage example

SELECT arrayLevenshteinDistanceWeighted(['A', 'B', 'C'], ['A', 'K', 'L'], [1.0, 2, 3], [3.0, 4, 5])

14

Introduced in version 25.4.

arrayMap

Returns an array obtained from the original arrays by applying a lambda function to each element.

Syntax

arrayMap(func, arr)

Arguments

• func — A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• arr — N arrays to process. Array(T)

Returned value

Returns an array from the lambda results Array(T)

Examples

Usage example

SELECT arrayMap(x -> (x + 2), [1, 2, 3]) as res;

[3, 4, 5]

Creating a tuple of elements from different arrays

SELECT arrayMap((x, y) -> (x, y), [1, 2, 3], [4, 5, 6]) AS res

[(1, 4),(2, 5),(3, 6)]

Introduced in version 1.1.

arrayMax

Returns the maximum element in the source array.

If a lambda function func is specified, returns the maximum element of the lambda results.

Syntax

arrayMax([func(x[, y1, ..., yN])], source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — Optional. A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Array(T)
• [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns the maximum element in the source array, or the maximum element of the lambda results if provided.

Examples

Basic example

SELECT arrayMax([5, 3, 2, 7]);

7

Usage with lambda function

SELECT arrayMax(x, y -> x/y, [4, 8, 12, 16], [1, 2, 1, 2]);

12

Introduced in version 21.1.

arrayMin

Returns the minimum element in the source array.

If a lambda function func is specified, returns the minimum element of the lambda results.

Syntax

arrayMin([func(x[, y1, ..., yN])], source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — Optional. A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Array(T)
• cond1_arr, ... — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns the minimum element in the source array, or the minimum element of the lambda results if provided.

Examples

Basic example

SELECT arrayMin([5, 3, 2, 7]);

2

Usage with lambda function

SELECT arrayMin(x, y -> x/y, [4, 8, 12, 16], [1, 2, 1, 2]);

4

Introduced in version 21.1.

arrayNormalizedGini

Calculates the normalized Gini coefficient.

Syntax

arrayNormalizedGini(predicted, label)

Arguments

• predicted — The predicted value. Array(T)
• label — The actual value. Array(T)

Returned value

A tuple containing the Gini coefficients of the predicted values, the Gini coefficient of the normalized values, and the normalized Gini coefficient (= the ratio of the former two Gini coefficients) Tuple(Float64, Float64, Float64)

Examples

Usage example

SELECT arrayNormalizedGini([0.9, 0.3, 0.8, 0.7],[6, 1, 0, 2]);

(0.18055555555555558, 0.2638888888888889, 0.6842105263157896)

Introduced in version 25.1.

arrayPartialReverseSort

This function is the same as arrayReverseSort but with an additional limit argument allowing partial sorting.

:::tip To retain only the sorted elements use arrayResize. :::

Syntax

arrayPartialReverseSort([f,] arr [, arr1, ... ,arrN], limit)

Arguments

• f(arr[, arr1, ... ,arrN]) — The lambda function to apply to elements of array x. Lambda function
• arr — Array to be sorted. Array(T)
• arr1, ... ,arrN — N additional arrays, in the case when f accepts multiple arguments. Array(T)
• limit — Index value up until which sorting will occur. (U)Int*

Returned value

Returns an array of the same size as the original array where elements in the range [1..limit] are sorted in descending order. The remaining elements (limit..N] are in an unspecified order.

Examples

simple_int

SELECT arrayPartialReverseSort(2, [5, 9, 1, 3])

[9, 5, 1, 3]

simple_string

SELECT arrayPartialReverseSort(2, ['expenses','lasso','embolism','gladly'])

['lasso','gladly','expenses','embolism']

retain_sorted

SELECT arrayResize(arrayPartialReverseSort(2, [5, 9, 1, 3]), 2)

[9, 5]

lambda_simple

SELECT arrayPartialReverseSort((x) -> -x, 2, [5, 9, 1, 3])

[1, 3, 5, 9]

lambda_complex

SELECT arrayPartialReverseSort((x, y) -> -y, 1, [0, 1, 2], [1, 2, 3]) as res

[0, 1, 2]

Introduced in version 23.2.

arrayPartialShuffle

Returns an array of the same size as the original array where elements in range [1..limit] are a random subset of the original array. Remaining (limit..n] shall contain the elements not in [1..limit] range in undefined order. Value of limit shall be in range [1..n]. Values outside of that range are equivalent to performing full arrayShuffle:

:::note This function will not materialize constants.

The value of limit should be in the range [1..N]. Values outside of that range are equivalent to performing full arrayShuffle. :::

Syntax

arrayPartialShuffle(arr [, limit[, seed]])

Arguments

• arr — The array to shuffle. Array(T)
• seed — Optional. The seed to be used with random number generation. If not provided, a random one is used. (U)Int*
• limit — Optional. The number to limit element swaps to, in the range [1..N]. (U)Int*

Returned value

Array with elements partially shuffled. Array(T)

Examples

no_limit1

SELECT arrayPartialShuffle([1, 2, 3, 4], 0)

[2, 4, 3, 1]

no_limit2

SELECT arrayPartialShuffle([1, 2, 3, 4])

[4, 1, 3, 2]

random_seed

SELECT arrayPartialShuffle([1, 2, 3, 4], 2)

[3, 4, 1, 2]

explicit_seed

SELECT arrayPartialShuffle([1, 2, 3, 4], 2, 41)

[3, 2, 1, 4]

materialize

SELECT arrayPartialShuffle(materialize([1, 2, 3, 4]), 2, 42), arrayPartialShuffle([1, 2, 3], 2, 42) FROM numbers(10)

┌─arrayPartial⋯4]), 2, 42)─┬─arrayPartial⋯ 3], 2, 42)─┐
│ [3,2,1,4]                │ [3,2,1]                  │
│ [3,2,1,4]                │ [3,2,1]                  │
│ [4,3,2,1]                │ [3,2,1]                  │
│ [1,4,3,2]                │ [3,2,1]                  │
│ [3,4,1,2]                │ [3,2,1]                  │
│ [1,2,3,4]                │ [3,2,1]                  │
│ [1,4,3,2]                │ [3,2,1]                  │
│ [1,4,3,2]                │ [3,2,1]                  │
│ [3,1,2,4]                │ [3,2,1]                  │
│ [1,3,2,4]                │ [3,2,1]                  │
└──────────────────────────┴──────────────────────────┘

Introduced in version 23.2.

arrayPartialSort

This function is the same as arraySort but with an additional limit argument allowing partial sorting.

:::tip To retain only the sorted elements use arrayResize. :::

Syntax

arrayPartialSort([f,] arr [, arr1, ... ,arrN], limit)

Arguments

• f(arr[, arr1, ... ,arrN]) — The lambda function to apply to elements of array x. Lambda function
• arr — Array to be sorted. Array(T)
• arr1, ... ,arrN — N additional arrays, in the case when f accepts multiple arguments. Array(T)
• limit — Index value up until which sorting will occur. (U)Int*

Returned value

Returns an array of the same size as the original array where elements in the range [1..limit] are sorted in ascending order. The remaining elements (limit..N] are in an unspecified order.

Examples

simple_int

SELECT arrayPartialSort(2, [5, 9, 1, 3])

[1, 3, 5, 9]

simple_string

SELECT arrayPartialSort(2, ['expenses', 'lasso', 'embolism', 'gladly'])

['embolism', 'expenses', 'gladly', 'lasso']

retain_sorted

SELECT arrayResize(arrayPartialSort(2, [5, 9, 1, 3]), 2)

[1, 3]

lambda_simple

SELECT arrayPartialSort((x) -> -x, 2, [5, 9, 1, 3])

[9, 5, 1, 3]

lambda_complex

SELECT arrayPartialSort((x, y) -> -y, 1, [0, 1, 2], [1, 2, 3]) as res

[2, 1, 0]

Introduced in version 23.2.

arrayPopBack

Removes the last element from the array.

Syntax

arrayPopBack(arr)

Arguments

• arr — The array for which to remove the last element from. Array(T)

Returned value

Returns an array identical to arr but without the last element of arr Array(T)

Examples

Usage example

SELECT arrayPopBack([1, 2, 3]) AS res;

[1, 2]

Introduced in version 1.1.

arrayPopFront

Removes the first item from the array.

Syntax

arrayPopFront(arr)

Arguments

• arr — The array for which to remove the first element from. Array(T)

Returned value

Returns an array identical to arr but without the first element of arr Array(T)

Examples

Usage example

SELECT arrayPopFront([1, 2, 3]) AS res;

[2, 3]

Introduced in version 1.1.

arrayProduct

Returns the product of elements in the source array.

If a lambda function func is specified, returns the product of elements of the lambda results.

Syntax

arrayProduct([func(x[, y1, ..., yN])], source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — Optional. A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Array(T)
• [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns the product of elements in the source array, or the product of elements of the lambda results if provided. Float64

Examples

Basic example

SELECT arrayProduct([1, 2, 3, 4]);

24

Usage with lambda function

SELECT arrayProduct(x, y -> x+y, [2, 2], [2, 2]) AS res;

16

Introduced in version 21.1.

arrayPushBack

Adds one item to the end of the array.

Syntax

arrayPushBack(arr, x)

Arguments

• arr — The array for which to add value x to the end of. Array(T)
• x —
• Single value to add to the end of the array. Array(T).

:::note

• Only numbers can be added to an array with numbers, and only strings can be added to an array of strings.
• When adding numbers, RawTree automatically sets the type of x for the data type of the array.
• Can be NULL. The function adds a NULL element to an array, and the type of array elements converts to Nullable.

For more information about the types of data in RawTree, see Data types. :::

Returned value

Returns an array identical to arr but with an additional value x at the end of the array Array(T)

Examples

Usage example

SELECT arrayPushBack(['a'], 'b') AS res;

['a','b']

Introduced in version 1.1.

arrayPushFront

Adds one element to the beginning of the array.

Syntax

arrayPushFront(arr, x)

Arguments

• arr — The array for which to add value x to the end of. Array(T). - x —
• Single value to add to the start of the array. Array(T).

:::note

• Only numbers can be added to an array with numbers, and only strings can be added to an array of strings.
• When adding numbers, RawTree automatically sets the type of x for the data type of the array.
• Can be NULL. The function adds a NULL element to an array, and the type of array elements converts to Nullable.

For more information about the types of data in RawTree, see Data types. :::

Returned value

Returns an array identical to arr but with an additional value x at the beginning of the array Array(T)

Examples

Usage example

SELECT arrayPushFront(['b'], 'a') AS res;

['a','b']

Introduced in version 1.1.

arrayROCAUC

Calculates the area under the receiver operating characteristic (ROC) curve. A ROC curve is created by plotting True Positive Rate (TPR) on the y-axis and False Positive Rate (FPR) on the x-axis across all thresholds. The resulting value ranges from zero to one, with a higher value indicating better model performance.

The ROC AUC (also known as simply AUC) is a concept in machine learning. For more details, please see here, here and here.

Syntax

arrayROCAUC(scores, labels[, scale[, partial_offsets]])

Arguments

• scores — Scores prediction model gives. Array((U)Int*) or Array(Float*)
• labels — Labels of samples, usually 1 for positive sample and 0 for negative sample. Array((U)Int*) or Enum
• scale — Optional. Decides whether to return the normalized area. If false, returns the area under the TP (true positives) x FP (false positives) curve instead. Default value: true. Bool
• partial_offsets —
• An array of four non-negative integers for calculating a partial area under the ROC curve (equivalent to a vertical band of the ROC space) instead of the whole AUC. This option is useful for distributed computation of the ROC AUC. The array must contain the following elements [higher_partitions_tp, higher_partitions_fp, total_positives, total_negatives]. Array of non-negative Integers. Optional.
  • higher_partitions_tp: The number of positive labels in the higher-scored partitions.
  • higher_partitions_fp: The number of negative labels in the higher-scored partitions.
  • total_positives: The total number of positive samples in the entire dataset.
  • total_negatives: The total number of negative samples in the entire dataset.

:::note When arr_partial_offsets is used, the arr_scores and arr_labels should be only a partition of the entire dataset, containing an interval of scores. The dataset should be divided into contiguous partitions, where each partition contains the subset of the data whose scores fall within a specific range. For example:

• One partition could contain all scores in the range [0, 0.5).
• Another partition could contain scores in the range [0.5, 1.0]. :::

Returned value

Returns area under the receiver operating characteristic (ROC) curve. Float64

Examples

Usage example

SELECT arrayROCAUC([0.1, 0.4, 0.35, 0.8], [0, 0, 1, 1]);

0.75

Introduced in version 20.4.

arrayRandomSample

Returns a subset with samples-many random elements of an input array. If samples exceeds the size of the input array, the sample size is limited to the size of the array, i.e. all array elements are returned but their order is not guaranteed. The function can handle both flat arrays and nested arrays.

Syntax

arrayRandomSample(arr, samples)

Arguments

• arr — The input array or multidimensional array from which to sample elements. Array(T)
• samples — The number of elements to include in the random sample. (U)Int*

Returned value

An array containing a random sample of elements from the input array Array(T)

Examples

Usage example

SELECT arrayRandomSample(['apple', 'banana', 'cherry', 'date'], 2) as res;

['cherry','apple']

Using a multidimensional array

SELECT arrayRandomSample([[1, 2], [3, 4], [5, 6]], 2) as res;

[[3,4],[5,6]]

Introduced in version 23.10.

arrayReduce

Applies an aggregate function to array elements and returns its result. The name of the aggregation function is passed as a string in single quotes 'max', 'sum'. When using parametric aggregate functions, the parameter is indicated after the function name in parentheses 'uniqUpTo(6)'.

Syntax

arrayReduce(agg_f, arr1 [, arr2, ... , arrN)])

Arguments

• agg_f — The name of an aggregate function which should be a constant. String
• arr1 [, arr2, ... , arrN)] — N arrays corresponding to the arguments of agg_f. Array(T)

Returned value

Returns the result of the aggregate function

Examples

Usage example

SELECT arrayReduce('max', [1, 2, 3]);

┌─arrayReduce('max', [1, 2, 3])─┐
│                             3 │
└───────────────────────────────┘

Example with aggregate function using multiple arguments

--If an aggregate function takes multiple arguments, then this function must be applied to multiple arrays of the same size.

SELECT arrayReduce('maxIf', [3, 5], [1, 0]);

┌─arrayReduce('maxIf', [3, 5], [1, 0])─┐
│                                    3 │
└──────────────────────────────────────┘

Example with a parametric aggregate function

SELECT arrayReduce('uniqUpTo(3)', [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);

┌─arrayReduce('uniqUpTo(3)', [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])─┐
│                                                           4 │
└─────────────────────────────────────────────────────────────┘

Introduced in version 1.1.

arrayReduceInRanges

Applies an aggregate function to array elements in the given ranges and returns an array containing the result corresponding to each range. The function will return the same result as multiple arrayReduce(agg_func, arraySlice(arr1, index, length), ...).

Syntax

arrayReduceInRanges(agg_f, ranges, arr1 [, arr2, ... ,arrN)])

Arguments

• agg_f — The name of the aggregate function to use. String
• ranges — The range over which to aggregate. An array of tuples, (i, r) containing the index i from which to begin from and the range r over which to aggregate. Array(T) or Tuple(T)
• arr1 [, arr2, ... ,arrN)] — N arrays as arguments to the aggregate function. Array(T)

Returned value

Returns an array containing results of the aggregate function over the specified ranges Array(T)

Examples

Usage example

SELECT arrayReduceInRanges(
    'sum',
    [(1, 5), (2, 3), (3, 4), (4, 4)],
    [1000000, 200000, 30000, 4000, 500, 60, 7]
) AS res

┌─res─────────────────────────┐
│ [1234500,234000,34560,4567] │
└─────────────────────────────┘

Introduced in version 20.4.

arrayRemove

Removes all elements equal to a given value from an array. NULLs are treated as equal.

Syntax

arrayRemove(arr, elem)

Arguments

• arr — Array(T) - elem — T

Returned value

Returns a subset of the source array Array(T)

Examples

Example 1

SELECT arrayRemove([1, 2, 2, 3], 2)

[1, 3]

Example 2

SELECT arrayRemove(['a', NULL, 'b', NULL], NULL)

['a', 'b']

Introduced in version 25.11.

arrayResize

Changes the length of the array.

Syntax

arrayResize(arr, size[, extender])

Arguments

• arr — Array to resize. Array(T)
• size — -The new length of the array. If size is less than the original size of the array, the array is truncated from the right. If size is larger than the initial size of the array, the array is extended to the right with extender values or default values for the data type of the array items.
• extender — Value to use for extending the array. Can be NULL.

Returned value

An array of length size. Array(T)

Examples

Example 1

SELECT arrayResize([1], 3);

[1,0,0]

Example 2

SELECT arrayResize([1], 3, NULL);

[1,NULL,NULL]

Introduced in version 1.1.

arrayReverse

Reverses the order of elements of a given array.

:::note Function reverse(arr) performs the same functionality but works on other data-types in addition to Arrays. :::

Syntax

arrayReverse(arr)

Arguments

• arr — The array to reverse. Array(T)

Returned value

Returns an array of the same size as the original array containing the elements in reverse order Array(T)

Examples

Usage example

SELECT arrayReverse([1, 2, 3])

[3,2,1]

Introduced in version 1.1.

arrayReverseFill

The arrayReverseFill function sequentially processes a source array from the last element to the first, evaluating a lambda condition at each position using elements from the source and condition arrays. When the condition evaluates to false at position i, the function replaces that element with the element at position i+1 from the current state of the array. The last element is always preserved regardless of any condition.

Syntax

arrayReverseFill(func(x[, y1, ..., yN]), source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Array(T)
• [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns an array with elements of the source array replaced by the results of the lambda. Array(T)

Examples

Example with a single array

SELECT arrayReverseFill(x -> not isNull(x), [1, null, 2, null]) AS res

[1, 2, 2, NULL]

Example with two arrays

SELECT arrayReverseFill(x, y, z -> x > y AND x < z, [5, 3, 6, 2], [4, 7, 1, 3], [10, 2, 8, 5]) AS res;

[5, 6, 6, 2]

Introduced in version 20.1.

arrayReverseSort

Sorts the elements of an array in descending order. If a function f is specified, the provided array is sorted according to the result of the function applied to the elements of the array, and then the sorted array is reversed. If f accepts multiple arguments, the arrayReverseSort function is passed several arrays that the arguments of func will correspond to.

If the array to sort contains -Inf, NULL, NaN, or Inf they will be sorted in the following order:

1. -Inf
2. Inf
3. NaN
4. NULL

arrayReverseSort is a higher-order function.

Syntax

arrayReverseSort([f,] arr [, arr1, ... ,arrN)

Arguments

• f(y1[, y2 ... yN]) — The lambda function to apply to elements of array x. - arr — An array to be sorted. Array(T) - arr1, ..., yN — Optional. N additional arrays, in the case when f accepts multiple arguments.

Returned value

Returns the array x sorted in descending order if no lambda function is provided, otherwise it returns an array sorted according to the logic of the provided lambda function, and then reversed. Array(T).

Examples

Example 1

SELECT arrayReverseSort((x, y) -> y, [4, 3, 5], ['a', 'b', 'c']) AS res;

[5,3,4]

Example 2

SELECT arrayReverseSort((x, y) -> -y, [4, 3, 5], [1, 2, 3]) AS res;

[4,3,5]

Introduced in version 1.1.

arrayReverseSplit

Split a source array into multiple arrays. When func(x[, y1, ..., yN]) returns something other than zero, the array will be split to the right of the element. The array will not be split after the last element.

Syntax

arrayReverseSplit(func(x[, y1, ..., yN]), source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Lambda function
• [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns an array of arrays. Array(Array(T))

Examples

Usage example

SELECT arrayReverseSplit((x, y) -> y, [1, 2, 3, 4, 5], [1, 0, 0, 1, 0]) AS res

[[1], [2, 3, 4], [5]]

Introduced in version 20.1.

arrayRotateLeft

Rotates an array to the left by the specified number of elements. Negative values of n are treated as rotating to the right by the absolute value of the rotation.

Syntax

arrayRotateLeft(arr, n)

Arguments

• arr — The array for which to rotate the elements.Array(T). - n — Number of elements to rotate. (U)Int8/16/32/64.

Returned value

An array rotated to the left by the specified number of elements Array(T)

Examples

Usage example

SELECT arrayRotateLeft([1,2,3,4,5,6], 2) as res;

[3,4,5,6,1,2]

Negative value of n

SELECT arrayRotateLeft([1,2,3,4,5,6], -2) as res;

[5,6,1,2,3,4]

Introduced in version 23.8.

arrayRotateRight

Rotates an array to the right by the specified number of elements. Negative values of n are treated as rotating to the left by the absolute value of the rotation.

Syntax

arrayRotateRight(arr, n)

Arguments

• arr — The array for which to rotate the elements.Array(T). - n — Number of elements to rotate. (U)Int8/16/32/64.

Returned value

An array rotated to the right by the specified number of elements Array(T)

Examples

Usage example

SELECT arrayRotateRight([1,2,3,4,5,6], 2) as res;

[5,6,1,2,3,4]

Negative value of n

SELECT arrayRotateRight([1,2,3,4,5,6], -2) as res;

[3,4,5,6,1,2]

Introduced in version 23.8.

arrayShiftLeft

Shifts an array to the left by the specified number of elements. New elements are filled with the provided argument or the default value of the array element type. If the number of elements is negative, the array is shifted to the right.

Syntax

arrayShiftLeft(arr, n[, default])

Arguments

• arr — The array for which to shift the elements.Array(T). - n — Number of elements to shift.(U)Int8/16/32/64. - default — Optional. Default value for new elements.

Returned value

An array shifted to the left by the specified number of elements Array(T)

Examples

Usage example

SELECT arrayShiftLeft([1,2,3,4,5,6], 2) as res;

[3,4,5,6,0,0]

Negative value of n

SELECT arrayShiftLeft([1,2,3,4,5,6], -2) as res;

[0,0,1,2,3,4]

Using a default value

SELECT arrayShiftLeft([1,2,3,4,5,6], 2, 42) as res;

[3,4,5,6,42,42]

Introduced in version 23.8.

arrayShiftRight

Shifts an array to the right by the specified number of elements. New elements are filled with the provided argument or the default value of the array element type. If the number of elements is negative, the array is shifted to the left.

Syntax

arrayShiftRight(arr, n[, default])

Arguments

• arr — The array for which to shift the elements. Array(T)
• n — Number of elements to shift. (U)Int8/16/32/64
• default — Optional. Default value for new elements.

Returned value

An array shifted to the right by the specified number of elements Array(T)

Examples

Usage example

SELECT arrayShiftRight([1, 2, 3, 4, 5, 6], 2) as res;

[0, 0, 1, 2, 3, 4]

Negative value of n

SELECT arrayShiftRight([1, 2, 3, 4, 5, 6], -2) as res;

[3, 4, 5, 6, 0, 0]

Using a default value

SELECT arrayShiftRight([1, 2, 3, 4, 5, 6], 2, 42) as res;

[42, 42, 1, 2, 3, 4]

Introduced in version 23.8.

arrayShingles

Generates an array of shingles (similar to ngrams for strings), i.e. consecutive sub-arrays with a specified length of the input array.

Syntax

arrayShingles(arr, l)

Arguments

• arr — Array for which to generate an array of shingles. Array(T)
• l — The length of each shingle. (U)Int*

Returned value

An array of generated shingles Array(T)

Examples

Usage example

SELECT arrayShingles([1, 2, 3, 4], 3) as res;

[[1, 2, 3], [2, 3, 4]]

Introduced in version 24.1.

arrayShuffle

Returns an array of the same size as the original array containing the elements in shuffled order. Elements are reordered in such a way that each possible permutation of those elements has equal probability of appearance.

:::note This function will not materialize constants. :::

Syntax

arrayShuffle(arr [, seed])

Arguments

• arr — The array to shuffle. Array(T)
• seed (optional) — Optional. The seed to be used with random number generation. If not provided a random one is used. (U)Int*

Returned value

Array with elements shuffled Array(T)

Examples

Example without seed (unstable results)

SELECT arrayShuffle([1, 2, 3, 4]);

[1,4,2,3]

Example without seed (stable results)

SELECT arrayShuffle([1, 2, 3, 4], 41);

[3,2,1,4]

Introduced in version 23.2.

arraySimilarity

Calculates the similarity of two arrays from 0 to 1 based on weighted Levenshtein distance.

Syntax

arraySimilarity(from, to, from_weights, to_weights)

Arguments

• from — first array Array(T)
• to — second array Array(T)
• from_weights — weights for the first array. Array((U)Int*|Float*)
• to_weights — weights for the second array. Array((U)Int*|Float*)

Returned value

Returns the similarity between 0 and 1 of the two arrays based on the weighted Levenshtein distance Float64

Examples

Usage example

SELECT arraySimilarity(['A', 'B', 'C'], ['A', 'K', 'L'], [1.0, 2, 3], [3.0, 4, 5]);

0.2222222222222222

Introduced in version 25.4.

arraySlice

Returns a slice of the array, with NULL elements included.

Syntax

arraySlice(arr, offset [, length])

Arguments

• arr — Array to slice. Array(T)
• offset — Indent from the edge of the array. A positive value indicates an offset on the left, and a negative value is an indent on the right. Numbering of the array items begins with 1. (U)Int*
• length — The length of the required slice. If you specify a negative value, the function returns an open slice [offset, array_length - length]. If you omit the value, the function returns the slice [offset, the_end_of_array]. (U)Int*

Returned value

Returns a slice of the array with length elements from the specified offset Array(T)

Examples

Usage example

SELECT arraySlice([1, 2, NULL, 4, 5], 2, 3) AS res;

[2, NULL, 4]

Introduced in version 1.1.

arraySort

Sorts the elements of the provided array in ascending order. If a lambda function f is specified, sorting order is determined by the result of the lambda applied to each element of the array. If the lambda accepts multiple arguments, the arraySort function is passed several arrays that the arguments of f will correspond to.

If the array to sort contains -Inf, NULL, NaN, or Inf they will be sorted in the following order:

1. -Inf
2. Inf
3. NaN
4. NULL

arraySort is a higher-order function.

Syntax

arraySort([f,] arr [, arr1, ... ,arrN])

Arguments

• f(y1[, y2 ... yN]) — The lambda function to apply to elements of array x. - arr — An array to be sorted. Array(T) - arr1, ..., yN — Optional. N additional arrays, in the case when f accepts multiple arguments.

Returned value

Returns the array arr sorted in ascending order if no lambda function is provided, otherwise it returns an array sorted according to the logic of the provided lambda function. Array(T).

Examples

Example 1

SELECT arraySort([1, 3, 3, 0]);

[0,1,3,3]

Example 2

SELECT arraySort(['hello', 'world', '!']);

['!','hello','world']

Example 3

SELECT arraySort([1, nan, 2, NULL, 3, nan, -4, NULL, inf, -inf]);

[-inf,-4,1,2,3,inf,nan,nan,NULL,NULL]

Introduced in version 1.1.

arraySplit

Split a source array into multiple arrays. When func(x [, y1, ..., yN]) returns something other than zero, the array will be split to the left of the element. The array will not be split before the first element.

Syntax

arraySplit(func(x[, y1, ..., yN]), source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — A lambda function which operates on elements of the source array (x) and condition arrays (y).Lambda function. - source_arr — The source array to split Array(T). - [, cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T).

Returned value

Returns an array of arrays Array(Array(T))

Examples

Usage example

SELECT arraySplit((x, y) -> y, [1, 2, 3, 4, 5], [1, 0, 0, 1, 0]) AS res

[[1, 2, 3], [4, 5]]

Introduced in version 20.1.

arraySum

Returns the sum of elements in the source array.

If a lambda function func is specified, returns the sum of elements of the lambda results.

Syntax

arrayMax([func(x[, y1, ..., yN])], source_arr[, cond1_arr, ... , condN_arr])

Arguments

• func(x[, y1, ..., yN]) — Optional. A lambda function which operates on elements of the source array (x) and condition arrays (y). Lambda function
• source_arr — The source array to process. Array(T)
• , cond1_arr, ... , condN_arr] — Optional. N condition arrays providing additional arguments to the lambda function. Array(T)

Returned value

Returns the sum of elements in the source array, or the sum of elements of the lambda results if provided.

Examples

Basic example

SELECT arraySum([1, 2, 3, 4]);

10

Usage with lambda function

SELECT arraySum(x, y -> x+y, [1, 1, 1, 1], [1, 1, 1, 1]);

8

Introduced in version 21.1.

arraySymmetricDifference

Takes multiple arrays and returns an array with elements that are not present in all source arrays. The result contains only unique values.

:::note The symmetric difference of more than two sets is mathematically defined as the set of all input elements which occur in an odd number of input sets. In contrast, function arraySymmetricDifference simply returns the set of input elements which do not occur in all input sets. :::

Syntax

arraySymmetricDifference(arr1, arr2, ... , arrN)

Arguments

• arrN — N arrays from which to make the new array. Array(T).

Returned value

Returns an array of distinct elements not present in all source arrays Array(T)

Examples

Usage example

SELECT
arraySymmetricDifference([1, 2], [1, 2], [1, 2]) AS empty_symmetric_difference,
arraySymmetricDifference([1, 2], [1, 2], [1, 3]) AS non_empty_symmetric_difference;

┌─empty_symmetric_difference─┬─non_empty_symmetric_difference─┐
│ []                         │ [3]                            │
└────────────────────────────┴────────────────────────────────┘

Introduced in version 25.4.

arrayUnion

Takes multiple arrays and returns an array which contains all elements that are present in one of the source arrays.The result contains only unique values.

Syntax

arrayUnion(arr1, arr2, ..., arrN)

Arguments

• arrN — N arrays from which to make the new array. Array(T)

Returned value

Returns an array with distinct elements from the source arrays Array(T)

Examples

Usage example

SELECT
arrayUnion([-2, 1], [10, 1], [-2], []) as num_example,
arrayUnion(['hi'], [], ['hello', 'hi']) as str_example,
arrayUnion([1, 3, NULL], [2, 3, NULL]) as null_example

┌─num_example─┬─str_example────┬─null_example─┐
│ [10,-2,1]   │ ['hello','hi'] │ [3,2,1,NULL] │
└─────────────┴────────────────┴──────────────┘

Introduced in version 24.10.

arrayUniq

For a single argument passed, counts the number of different elements in the array. For multiple arguments passed, it counts the number of different tuples made of elements at matching positions across multiple arrays.

For example SELECT arrayUniq([1,2], [3,4], [5,6]) will form the following tuples:

• Position 1: (1,3,5)
• Position 2: (2,4,6)

It will then count the number of unique tuples. In this case 2.

All arrays passed must have the same length.

:::tip If you want to get a list of unique items in an array, you can use arrayReduce('groupUniqArray', arr). :::

Syntax

arrayUniq(arr1[, arr2, ..., arrN])

Arguments

• arr1 — Array for which to count the number of unique elements. Array(T)
• [, arr2, ..., arrN] — Optional. Additional arrays used to count the number of unique tuples of elements at corresponding positions in multiple arrays. Array(T)

Returned value

For a single argument returns the number of unique elements. For multiple arguments returns the number of unique tuples made from elements at corresponding positions across the arrays. UInt32

Examples

Single argument

SELECT arrayUniq([1, 1, 2, 2])

2

Multiple argument

SELECT arrayUniq([1, 2, 3, 1], [4, 5, 6, 4])

3

Introduced in version 1.1.