ARRAY_POSITION function - Amazon Redshift

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ARRAY_POSITION function

Returns the position (index) of the first occurrence of a specified element in an array. The index is 0-based, where 0 indicates the first element, 1 indicates the second element, and so on. Returns -1 if the element is not found in the array.

The function returns only the position of the first occurrence. To find all occurrences, consider using the ARRAY_POSITIONS function function.

Syntax

ARRAY_POSITION( array, value [, null_match] )

Arguments

array

A SUPER expression that specifies the array in which to search.

value

A value that specifies the element to search for.

null_match

A boolean value that specifies how NULL values are handled:

  • null_match = FALSE: Searching for NULL returns NULL. If the array contains NULL values and no match is found for a non-NULL search value, returns NULL.
  • null_match = TRUE: NULLs are treated as valid, searchable elements. If the array contains NULL values and no match is found for a non-NULL search value, it returns -1.

The default is TRUE.

Default NULL handling can also be specified by the configuration option:

-- same as null_match = TRUE SET default_array_search_null_handling to TRUE;

Return type

The ARRAY_POSITION function returns an INT type.

Example

The following examples show the ARRAY_POSITION function.

SELECT ARRAY_POSITION(ARRAY('red', 'green'), 'red'); array_position ---------------- 0 (1 row) SELECT ARRAY_POSITION(ARRAY(1, 2, 3), 4); array_position ---------------- -1 (1 row) -- only the position of the first occurrence is returned SELECT ARRAY_POSITION(ARRAY('red', 'green', 'red'), 'red'); array_position ---------------- 0 (1 row)

The following examples show the function behavior with null_match set to TRUE.

SET default_array_search_null_handling to TRUE; -- NULL search is enabled SELECT ARRAY_POSITION(ARRAY('red', NULL, 'green'), NULL); array_position ---------------- 1 (1 row) -- The array can contain NULLs SELECT ARRAY_POSITION(ARRAY('red', NULL, 'green'), 'blue', TRUE); array_position ---------------- -1 (1 row)

The following examples show the function behavior with null_match set to FALSE. Note that specifying the null_match behavior in the function will override the default configuration setting.

-- same as null_match = TRUE SET default_array_search_null_handling to TRUE; -- NULL search is disabled. The default behavior is overridden SELECT ARRAY_POSITION(ARRAY('red', 'green'), NULL, FALSE); array_position ---------------- (1 row) -- same as null_match = FALSE SET default_array_search_null_handling to FALSE; -- The array contains NULL and a match is found SELECT ARRAY_POSITION(ARRAY('red', NULL, 'green'), 'green'); array_position ---------------- 2 (1 row) -- The array contains NULL but no match is found SELECT ARRAY_POSITION(ARRAY('red', NULL, 'green'), 'blue'); array_position ---------------- (1 row)

See also