Skip to main content
This function takes an integer n and a text sequence, then splits the sequence into overlapping contiguous subsequences of length n.

​
Syntax

​
Parameters

​
Return Types

ARRAY(TEXT)
  • If any of the inputs is nullable, the result type is ARRAY(TEXT) NULL.

​
Behavior

The function splits the input text into overlapping contiguous subsequences of length n.
  • If n is smaller than the size of the input text, an array containing the single value of the input text is returned.
  • If n is smaller than 1, an error is thrown.
  • If any input is NULL, the result is NULL regardless of the other input value.

​
Errors

An error is thrown if n is smaller than 1.

​
Respect/Ignore Nulls

Propagates nulls: If any input is NULL, the result is NULL.

​
Examples

The following example generates 2-grams (bigrams) from the string ‘hello world’:

Rows: 1Execution time: 5.56ms

The following example generates 3-grams (trigrams) from the string ‘hello world’:

Rows: 1Execution time: 5.68ms

The following example generates 1-grams (unigrams) from the string ‘hello’:

Rows: 1Execution time: 5.62ms

The following example generates 10-grams from the string ‘hi’. Since the string length matches the n-gram size, the result contains the entire string:

Rows: 1Execution time: 5.08ms

The following example uses an n-gram size of 0, which is invalid and throws an error:
ERROR: Line 1, Column 8: Invalid n-gram size: 0. Must be greater than 0. Choose an n-gram size larger than 0 or NULL. The following example uses a negative n-gram size, which is invalid and throws an error:
ERROR: Line 1, Column 8: Invalid n-gram size: -1. Must be greater than 0. Choose an n-gram size larger than 0 or NULL. The following example generates 2-grams (bigrams) from the Japanese string ‘こんにちは’:

Rows: 1Execution time: 5.10ms

The following example generates 2-grams (bigrams) from the string of emojis ’😊👍🎉‘:

Rows: 1Execution time: 5.69ms