APPLY_COUNT_ELEMENTS (ARRAY_LENGTH)

Returns the total number of elements in a collection (array or set), including NULLs. To count only non-null values, use APPLY_COUNT (ARRAY_COUNT).

Behavior type

Syntax

APPLY_COUNT_ELEMENTS(collection)

ARRAY_LENGTH is a synonym of APPLY_COUNT_ELEMENTS.

Arguments

collection

Target collection

Supported data types

• Arrays of any dimensionality and element type

• Sets of any element type

Null-handling

This function counts all members, including nulls.

An empty collection (ARRAY[] or SET[]) has a length of 0. A collection containing a single null (ARRAY[null] or SET[null]) has a length of 1.

Examples

The following array has six elements including one null:

=> SELECT apply_count_elements(ARRAY[1,NULL,3,7,8,5]);
apply_count_elements
---------------------
                   6
(1 row)

As the previous example shows, a null element is an element. Thus, an array containing only a null element has one element:

=> SELECT apply_count_elements(ARRAY[null]);
apply_count_elements
---------------------
                   1
(1 row)

A set does not contain duplicates. If you construct a set and pass it directly to this function, the result could differ from the number of inputs:

=> SELECT apply_count_elements(SET[1,1,3]);
apply_count_elements
---------------------
                   2
(1 row)