Functions for Working with Tuples

The function implements the operator .

Syntax

A function that allows getting a column from a tuple.
‘N’ is the column index, starting from 1. N must be a constant. ‘N’ must be a constant. ‘N’ must be a strict postive integer no greater than the size of the tuple.
There is no cost to execute the function.

The function implements the operator x.N.

Syntax

tupleElement(tuple, n)

Performs syntactic substitution of tuple elements in the call location.

Syntax

untuple(x)

You can use the EXCEPT expression to skip columns as a result of the query.

Arguments

• x — A tuple function, column, or tuple of elements. .

• None.

Examples

Input table:

┌─key─┬─v1─┬─v2─┬─v3─┬─v4─┬─v5─┬─v6────────┐
│   1 │ 10 │ 20 │ 40 │ 30 │ 15 │ (33,'ab') │
│   2 │ 25 │ 65 │ 70 │ 40 │  6 │ (44,'cd') │
│   3 │ 57 │ 30 │ 20 │ 10 │  5 │ (55,'ef') │
│   5 │ 30 │ 50 │ 70 │ 25 │ 55 │ (77,'kl') │

Example of using a Tuple-type column as the untuple function parameter:

Query:

Result:

┌─_ut_1─┬─_ut_2─┐
│    33 │ ab    │
│    44 │ cd    │
│    55 │ ef    │
│    66 │ gh    │
│    77 │ kl    │
└───────┴───────┘

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.

Example of using an EXCEPT expression:

Query:

SELECT untuple((* EXCEPT (v2, v3),)) FROM kv;

Result:

│   1 │ 10 │ 30 │ 15 │ (33,'ab') │
│   3 │ 57 │ 10 │  5 │ (55,'ef') │
│   4 │ 55 │ 80 │ 90 │ (66,'gh') │
│   5 │ 30 │ 25 │ 55 │ (77,'kl') │
└─────┴────┴────┴────┴───────────┘

• Tuple

Returns the between two tuples of the same size.

Syntax

Arguments

• tuple1 — First tuple. Tuple.
• tuple2 — Second tuple. .

Tuples should have the same type of the elements.

Returned value

• The Hamming distance.

Type: UInt8.

Examples

Query:

SELECT tupleHammingDistance((1, 2, 3), (3, 2, 1)) AS HammingDistance;

Result:

┌─HammingDistance─┐
│               2 │
└─────────────────┘

Result: