Postgres 13

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SELECT ARRAY[0.25, 0.5, 0.75]

array

{0.25,0.5,0.75}

SELECT 1

CREATE TABLE t(i INT);

INSERT INTO t VALUES (1),(2),(3),(4);

CREATE TABLE

INSERT 0 4

select 
       percentile_cont(ARRAY[0.25, 0.5, 0.75]) within group (order by i) as q25
from t

q25

{1.75,2.5,3.25}

SELECT 1

select 
       percentile_cont('{0.25, 0.5, 0.75}'::double precision[]) within group (order by i) as q25
from t

q25

{1.75,2.5,3.25}

SELECT 1