nanoid.sql

CREATE EXTENSION IF NOT EXISTS pgcrypto;

CREATE OR REPLACE FUNCTION nanoid(size int DEFAULT 12)
RETURNS text AS $$
DECLARE
  id text := '';
  idx int := 0;
  alphabet char(62) := '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
  bytes bytea := gen_random_bytes(size);
  byte int;
  pos int;
BEGIN
  WHILE idx < size LOOP
    byte := get_byte(bytes, idx);
    pos := (byte & 61) + 1;
    id := id || substr(alphabet, pos, 1);
    idx = idx + 1;
  END LOOP;
  RETURN id;
END
$$ LANGUAGE PLPGSQL STABLE;

-- SELECT nanoid(9);
-- Output: 'SmOiLHnGP'

Nano ID Collision Calculator: https://zelark.github.io/nano-id-cc/