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566 lines
13 KiB
Markdown
566 lines
13 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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‘N’ is the column index, starting from 1. ‘N’ must be a constant. ‘N’ must be a strict postive integer no greater than the size of the tuple.
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There is no cost to execute the function.
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The function implements the operator `x.N`.
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**Syntax**
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``` sql
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tupleElement(tuple, n)
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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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||
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```sql
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SELECT dotProduct((1, 2), (2, 3));
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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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## 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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