PostgreSQL 18 reference · Array Functions

PostgreSQL CARDINALITY() Function

Return the total number of elements in an array across all dimensions, and 0 for an empty array.

PostgreSQL 18 Since 9.4

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Syntax

cardinality(array)

Parameter	Description
`array`	An array value.

integer.

All dimensions

SELECT cardinality(ARRAY[[1, 2], [3, 4]]) AS elements;

Output

 elements
----------
        4
(1 row)

Run this on your computer — see “Get Started” for setup.

Count collected values

SELECT country, cardinality(array_agg(name)) AS customers
FROM customers
GROUP BY country
ORDER BY customers DESC
LIMIT 2;

Output

 country | customers
---------+-----------
 USA     |         5
 UK      |         2
(2 rows)

Run this on your computer — see “Get Started” for setup.

Version	Change
PostgreSQL 9.4	Added

ARRAY_LENGTH() · Return the length of one dimension of an array (use 1 for ordinary arrays). Empty arrays give NULL, not 0.
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