SET client_min_messages = warning;
CREATE EXTENSION IF NOT EXISTS vector;
SET enable_seqscan = off;
CREATE TABLE t (val vector(3));
INSERT INTO t (val) VALUES ('[0,0,0]'), ('[1,2,3]'), ('[1,1,1]'), (NULL);
CREATE INDEX ON t (val);
SELECT * FROM t WHERE val = '[1,2,3]';
   val   
---------
 [1,2,3]
(1 row)

SELECT * FROM t ORDER BY val LIMIT 1;
   val   
---------
 [0,0,0]
(1 row)

DROP TABLE t;