PostgreSQL 18 reference · JSON Functions

PostgreSQL JSONB_ARRAY_LENGTH() Function

Return the number of elements in a JSON array. Raises an error for objects and scalars.

PostgreSQL 18 Since 9.4

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Syntax

jsonb_array_length(jsonb)

Parameter	Description
`jsonb`	A `jsonb` (or `json`) value.

integer.

Count elements

SELECT jsonb_array_length('[1, 2, 3]') AS n;

Output

 n
---
 3
(1 row)

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

A nested array

SELECT jsonb_array_length('{"tags":["x","y"]}'::jsonb -> 'tags') AS tags;

Output

 tags
------
    2
(1 row)

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

Version	Change
PostgreSQL 9.4	Added

JSONB_ARRAY_ELEMENTS() · Expand a JSON array into one row per element. jsonb_array_elements_text() returns the elements as text.
JSONB_TYPEOF() · Return the type of the top-level JSON value: object, array, string, number, boolean or null.
CARDINALITY() · Return the total number of elements in an array across all dimensions, and 0 for an empty array.
SQL String Functions · tutorial