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How to Compare Arrays in PostgreSQL

The equality operators (=, <>) do an exact element-by-element comparison.

select
array[1,2,3] = array[1,2,4] as compare1, -- arrays are equal
array[1,2,3] <> array[1,2,4] as compare2; -- arrays are not equal
 compare1 | compare2
----------+----------
 f        | t

The ordering operators (>, <, >=, <=) also compare each element in an array in order. Results are based on the first different pair of elements, not the sizes of the arrays.

select
array[1,2,5] >= array[1,2,4] as compare1,
array[1,2,5] <= array[1,2,4,5] as compare2;
 compare1 | compare2
----------+----------
 t        | f

Then there are the containment operators (@>, <@). They are casually called "bird operators", well, because @> looks like a bird. An array is said to be contained in another array if each of its unique elements is also present in the other array.

-- This reads as array['a', 'b', 'c'] contains array['a', 'b', 'b', 'a']
select array['a', 'b', 'c'] @> array['a', 'b', 'b', 'a'] as contains;
 contains
----------
 t
-- this reads as array[1, 1, 4] is contained by array[4, 3, 2, 1]
select array[1, 1, 4] <@ array[4, 3, 2, 1] as is_contained_by;
 is_contained_by
-----------------
 t

Lastly, there is the overlap operator (&&). Arrays that have elements in common are called overlapping arrays. To check if two arrays overlap, use the && operator:

select
array[1, 2] && array[2, 3] as overlap1,
array[1, 2] && array[3, 4] as overlap2;
 overlap1 | overlap2
----------+----------
 t        | f

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