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 | tThe 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 | fThen 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
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tLastly, 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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