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566 lines
14 KiB
Markdown
566 lines
14 KiB
Markdown
---
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slug: /en/sql-reference/functions/tuple-functions
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sidebar_position: 66
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sidebar_label: Tuples
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title: "Functions for Working with Tuples"
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---
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## tuple
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A function that allows grouping multiple columns.
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For columns with the types T1, T2, …, it returns a Tuple(T1, T2, …) type tuple containing these columns. There is no cost to execute the function.
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Tuples are normally used as intermediate values for an argument of IN operators, or for creating a list of formal parameters of lambda functions. Tuples can’t be written to a table.
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The function implements the operator `(x, y, …)`.
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**Syntax**
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``` sql
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tuple(x, y, …)
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```
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## tupleElement
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A function that allows getting a column from a tuple.
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If the second argument is a number `n`, it is the column index, starting from 1. If the second argument is a string `s`, it represents the name of the element. Besides, we can provide the third optional argument, such that when index out of bounds or element for such name does not exist, the default value returned instead of throw exception. The second and third arguments if provided are always must be constant. There is no cost to execute the function.
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The function implements the operator `x.n` and `x.s`.
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**Syntax**
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``` sql
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tupleElement(tuple, n/s [, default_value])
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```
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## untuple
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Performs syntactic substitution of [tuple](../../sql-reference/data-types/tuple.md#tuplet1-t2) elements in the call location.
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**Syntax**
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``` sql
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untuple(x)
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```
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You can use the `EXCEPT` expression to skip columns as a result of the query.
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**Arguments**
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- `x` — A `tuple` function, column, or tuple of elements. [Tuple](../../sql-reference/data-types/tuple.md).
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**Returned value**
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- None.
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**Examples**
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Input table:
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``` text
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┌─key─┬─v1─┬─v2─┬─v3─┬─v4─┬─v5─┬─v6────────┐
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│ 1 │ 10 │ 20 │ 40 │ 30 │ 15 │ (33,'ab') │
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│ 2 │ 25 │ 65 │ 70 │ 40 │ 6 │ (44,'cd') │
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│ 3 │ 57 │ 30 │ 20 │ 10 │ 5 │ (55,'ef') │
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│ 4 │ 55 │ 12 │ 7 │ 80 │ 90 │ (66,'gh') │
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│ 5 │ 30 │ 50 │ 70 │ 25 │ 55 │ (77,'kl') │
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└─────┴────┴────┴────┴────┴────┴───────────┘
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```
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Example of using a `Tuple`-type column as the `untuple` function parameter:
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Query:
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``` sql
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SELECT untuple(v6) FROM kv;
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```
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Result:
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``` text
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┌─_ut_1─┬─_ut_2─┐
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│ 33 │ ab │
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│ 44 │ cd │
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│ 55 │ ef │
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│ 66 │ gh │
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│ 77 │ kl │
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└───────┴───────┘
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```
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Note: the names are implementation specific and are subject to change. You should not assume specific names of the columns after application of the `untuple`.
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Example of using an `EXCEPT` expression:
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Query:
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``` sql
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SELECT untuple((* EXCEPT (v2, v3),)) FROM kv;
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```
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Result:
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``` text
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┌─key─┬─v1─┬─v4─┬─v5─┬─v6────────┐
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│ 1 │ 10 │ 30 │ 15 │ (33,'ab') │
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│ 2 │ 25 │ 40 │ 6 │ (44,'cd') │
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│ 3 │ 57 │ 10 │ 5 │ (55,'ef') │
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│ 4 │ 55 │ 80 │ 90 │ (66,'gh') │
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│ 5 │ 30 │ 25 │ 55 │ (77,'kl') │
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└─────┴────┴────┴────┴───────────┘
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```
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**See Also**
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- [Tuple](../../sql-reference/data-types/tuple.md)
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## tupleHammingDistance
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Returns the [Hamming Distance](https://en.wikipedia.org/wiki/Hamming_distance) between two tuples of the same size.
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**Syntax**
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``` sql
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tupleHammingDistance(tuple1, tuple2)
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```
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**Arguments**
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- `tuple1` — First tuple. [Tuple](../../sql-reference/data-types/tuple.md).
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- `tuple2` — Second tuple. [Tuple](../../sql-reference/data-types/tuple.md).
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Tuples should have the same type of the elements.
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**Returned value**
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- The Hamming distance.
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Type: The result type is calculed the same way it is for [Arithmetic functions](../../sql-reference/functions/arithmetic-functions.md), based on the number of elements in the input tuples.
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``` sql
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SELECT
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toTypeName(tupleHammingDistance(tuple(0), tuple(0))) AS t1,
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toTypeName(tupleHammingDistance((0, 0), (0, 0))) AS t2,
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toTypeName(tupleHammingDistance((0, 0, 0), (0, 0, 0))) AS t3,
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toTypeName(tupleHammingDistance((0, 0, 0, 0), (0, 0, 0, 0))) AS t4,
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toTypeName(tupleHammingDistance((0, 0, 0, 0, 0), (0, 0, 0, 0, 0))) AS t5
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```
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``` text
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┌─t1────┬─t2─────┬─t3─────┬─t4─────┬─t5─────┐
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│ UInt8 │ UInt16 │ UInt32 │ UInt64 │ UInt64 │
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└───────┴────────┴────────┴────────┴────────┘
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```
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**Examples**
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Query:
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``` sql
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SELECT tupleHammingDistance((1, 2, 3), (3, 2, 1)) AS HammingDistance;
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```
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Result:
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``` text
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┌─HammingDistance─┐
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│ 2 │
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└─────────────────┘
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```
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Can be used with [MinHash](../../sql-reference/functions/hash-functions.md#ngramminhash) functions for detection of semi-duplicate strings:
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``` sql
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SELECT tupleHammingDistance(wordShingleMinHash(string), wordShingleMinHashCaseInsensitive(string)) as HammingDistance FROM (SELECT 'ClickHouse is a column-oriented database management system for online analytical processing of queries.' AS string);
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```
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Result:
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``` text
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┌─HammingDistance─┐
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│ 2 │
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└─────────────────┘
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```
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## tupleToNameValuePairs
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Turns a named tuple into an array of (name, value) pairs. For a `Tuple(a T, b T, ..., c T)` returns `Array(Tuple(String, T), ...)`
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in which the `Strings` represents the named fields of the tuple and `T` are the values associated with those names. All values in the tuple should be of the same type.
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**Syntax**
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``` sql
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tupleToNameValuePairs(tuple)
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```
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**Arguments**
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- `tuple` — Named tuple. [Tuple](../../sql-reference/data-types/tuple.md) with any types of values.
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**Returned value**
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- An array with (name, value) pairs.
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Type: [Array](../../sql-reference/data-types/array.md)([Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md), ...)).
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**Example**
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Query:
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``` sql
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CREATE TABLE tupletest (`col` Tuple(user_ID UInt64, session_ID UInt64) ENGINE = Memory;
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INSERT INTO tupletest VALUES (tuple( 100, 2502)), (tuple(1,100));
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SELECT tupleToNameValuePairs(col) FROM tupletest;
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```
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Result:
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``` text
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┌─tupleToNameValuePairs(col)────────────┐
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│ [('user_ID',100),('session_ID',2502)] │
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│ [('user_ID',1),('session_ID',100)] │
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└───────────────────────────────────────┘
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```
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It is possible to transform colums to rows using this function:
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``` sql
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CREATE TABLE tupletest (`col` Tuple(CPU Float64, Memory Float64, Disk Float64)) ENGINE = Memory;
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INSERT INTO tupletest VALUES(tuple(3.3, 5.5, 6.6));
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SELECT arrayJoin(tupleToNameValuePairs(col))FROM tupletest;
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```
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Result:
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``` text
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┌─arrayJoin(tupleToNameValuePairs(col))─┐
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│ ('CPU',3.3) │
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│ ('Memory',5.5) │
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│ ('Disk',6.6) │
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└───────────────────────────────────────┘
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```
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If you pass a simple tuple to the function, ClickHouse uses the indexes of the values as their names:
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``` sql
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SELECT tupleToNameValuePairs(tuple(3, 2, 1));
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```
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Result:
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``` text
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┌─tupleToNameValuePairs(tuple(3, 2, 1))─┐
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│ [('1',3),('2',2),('3',1)] │
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└───────────────────────────────────────┘
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```
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## tuplePlus
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Calculates the sum of corresponding values of two tuples of the same size.
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**Syntax**
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```sql
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tuplePlus(tuple1, tuple2)
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```
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Alias: `vectorSum`.
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**Arguments**
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- `tuple1` — First tuple. [Tuple](../../sql-reference/data-types/tuple.md).
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- `tuple2` — Second tuple. [Tuple](../../sql-reference/data-types/tuple.md).
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**Returned value**
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- Tuple with the sum.
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Type: [Tuple](../../sql-reference/data-types/tuple.md).
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**Example**
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Query:
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```sql
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SELECT tuplePlus((1, 2), (2, 3));
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```
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Result:
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```text
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┌─tuplePlus((1, 2), (2, 3))─┐
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│ (3,5) │
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└───────────────────────────┘
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```
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## tupleMinus
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Calculates the subtraction of corresponding values of two tuples of the same size.
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**Syntax**
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```sql
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tupleMinus(tuple1, tuple2)
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```
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Alias: `vectorDifference`.
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**Arguments**
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- `tuple1` — First tuple. [Tuple](../../sql-reference/data-types/tuple.md).
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- `tuple2` — Second tuple. [Tuple](../../sql-reference/data-types/tuple.md).
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**Returned value**
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- Tuple with the result of subtraction.
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Type: [Tuple](../../sql-reference/data-types/tuple.md).
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**Example**
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Query:
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```sql
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SELECT tupleMinus((1, 2), (2, 3));
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```
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Result:
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```text
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┌─tupleMinus((1, 2), (2, 3))─┐
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│ (-1,-1) │
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└────────────────────────────┘
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```
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## tupleMultiply
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Calculates the multiplication of corresponding values of two tuples of the same size.
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**Syntax**
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```sql
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tupleMultiply(tuple1, tuple2)
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```
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**Arguments**
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- `tuple1` — First tuple. [Tuple](../../sql-reference/data-types/tuple.md).
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- `tuple2` — Second tuple. [Tuple](../../sql-reference/data-types/tuple.md).
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**Returned value**
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- Tuple with the multiplication.
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Type: [Tuple](../../sql-reference/data-types/tuple.md).
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**Example**
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Query:
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```sql
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SELECT tupleMultiply((1, 2), (2, 3));
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```
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Result:
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```text
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┌─tupleMultiply((1, 2), (2, 3))─┐
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│ (2,6) │
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└───────────────────────────────┘
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```
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## tupleDivide
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Calculates the division of corresponding values of two tuples of the same size. Note that division by zero will return `inf`.
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**Syntax**
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```sql
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tupleDivide(tuple1, tuple2)
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```
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**Arguments**
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- `tuple1` — First tuple. [Tuple](../../sql-reference/data-types/tuple.md).
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- `tuple2` — Second tuple. [Tuple](../../sql-reference/data-types/tuple.md).
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**Returned value**
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- Tuple with the result of division.
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Type: [Tuple](../../sql-reference/data-types/tuple.md).
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**Example**
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Query:
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```sql
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SELECT tupleDivide((1, 2), (2, 3));
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```
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Result:
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```text
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┌─tupleDivide((1, 2), (2, 3))─┐
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│ (0.5,0.6666666666666666) │
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└─────────────────────────────┘
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```
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## tupleNegate
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Calculates the negation of the tuple values.
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**Syntax**
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```sql
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tupleNegate(tuple)
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```
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**Arguments**
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- `tuple` — [Tuple](../../sql-reference/data-types/tuple.md).
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**Returned value**
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- Tuple with the result of negation.
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Type: [Tuple](../../sql-reference/data-types/tuple.md).
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**Example**
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Query:
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```sql
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SELECT tupleNegate((1, 2));
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```
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Result:
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```text
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┌─tupleNegate((1, 2))─┐
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│ (-1,-2) │
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└─────────────────────┘
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```
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## tupleMultiplyByNumber
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Returns a tuple with all values multiplied by a number.
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**Syntax**
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```sql
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tupleMultiplyByNumber(tuple, number)
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```
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**Arguments**
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- `tuple` — [Tuple](../../sql-reference/data-types/tuple.md).
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- `number` — Multiplier. [Int/UInt](../../sql-reference/data-types/int-uint.md), [Float](../../sql-reference/data-types/float.md) or [Decimal](../../sql-reference/data-types/decimal.md).
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**Returned value**
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- Tuple with multiplied values.
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Type: [Tuple](../../sql-reference/data-types/tuple.md).
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**Example**
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Query:
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```sql
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SELECT tupleMultiplyByNumber((1, 2), -2.1);
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```
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Result:
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```text
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┌─tupleMultiplyByNumber((1, 2), -2.1)─┐
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│ (-2.1,-4.2) │
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└─────────────────────────────────────┘
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```
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## tupleDivideByNumber
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Returns a tuple with all values divided by a number. Note that division by zero will return `inf`.
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**Syntax**
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```sql
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tupleDivideByNumber(tuple, number)
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```
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**Arguments**
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- `tuple` — [Tuple](../../sql-reference/data-types/tuple.md).
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- `number` — Divider. [Int/UInt](../../sql-reference/data-types/int-uint.md), [Float](../../sql-reference/data-types/float.md) or [Decimal](../../sql-reference/data-types/decimal.md).
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**Returned value**
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- Tuple with divided values.
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Type: [Tuple](../../sql-reference/data-types/tuple.md).
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**Example**
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Query:
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```sql
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SELECT tupleDivideByNumber((1, 2), 0.5);
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```
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Result:
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```text
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┌─tupleDivideByNumber((1, 2), 0.5)─┐
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│ (2,4) │
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└──────────────────────────────────┘
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```
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## dotProduct
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Calculates the scalar product of two tuples of the same size.
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**Syntax**
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```sql
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dotProduct(tuple1, tuple2)
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```
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Alias: `scalarProduct`.
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**Arguments**
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- `tuple1` — First tuple. [Tuple](../../sql-reference/data-types/tuple.md).
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- `tuple2` — Second tuple. [Tuple](../../sql-reference/data-types/tuple.md).
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**Returned value**
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- Scalar product.
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Type: [Int/UInt](../../sql-reference/data-types/int-uint.md), [Float](../../sql-reference/data-types/float.md) or [Decimal](../../sql-reference/data-types/decimal.md).
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**Example**
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||
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Query:
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```sql
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SELECT dotProduct((1, 2), (2, 3));
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```
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||
|
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Result:
|
||
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```text
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┌─dotProduct((1, 2), (2, 3))─┐
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│ 8 │
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└────────────────────────────┘
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```
|
||
|
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|
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## Distance functions
|
||
|
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All supported functions are described in [distance functions documentation](../../sql-reference/functions/distance-functions.md).
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