Postgres 14

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.
CREATE TABLE tbl (tbl_id int, ts timestamp);
INSERT INTO tbl VALUES
  ( 1, '2013-09-01 00:01:00')
, ( 2, '2013-09-01 00:02:05')
, ( 3, '2013-09-01 00:02:06')
, ( 4, '2013-09-01 03:05:00')
, ( 5, '2013-09-01 03:05:00')
, ( 6, '2013-09-01 03:05:01')
, ( 7, '2013-09-01 03:10:00')
, ( 8, '2013-09-01 03:10:02')
, ( 9, '2013-09-01 03:25:00')
, (10, '2013-09-02 13:00:00')
, (11, '2013-09-02 13:01:00')
, (12, '2013-09-02 13:06:59')
, (12, '2013-09-02 13:07:00');


CREATE OR REPLACE FUNCTION f_rowgrid(i interval)
  RETURNS SETOF timestamp
  LANGUAGE plpgsql AS
$func$
DECLARE
   _this  timestamp;
   _last  timestamp := '-infinity';     -- init so that 1 row passes
BEGIN
   FOR _this IN
       SELECT ts FROM tbl ORDER BY 1
   LOOP
       IF _this >= _last + i THEN
          RETURN NEXT _this;
          _last := _this;
       END IF;
   END LOOP;
END
$func$;

CREATE TABLE



INSERT 0 13



CREATE FUNCTION


-- 'CTE'
WITH RECURSIVE cte AS (
   (
   SELECT ts FROM tbl
   ORDER BY ts
   LIMIT 1
   )

   UNION ALL
   (
   SELECT t.ts
   FROM   cte c
   JOIN   tbl t ON t.ts >= c.ts + interval '5 min'
   ORDER  BY t.ts
   LIMIT 1
   )
   )
TABLE cte ORDER BY ts;


ts


2013-09-01 00:01:00

2013-09-01 03:05:00

2013-09-01 03:10:00

2013-09-01 03:25:00

2013-09-02 13:00:00

2013-09-02 13:06:59



SELECT 6


-- function:
SELECT * FROM f_rowgrid('5 min');


f_rowgrid


2013-09-01 00:01:00

2013-09-01 03:05:00

2013-09-01 03:10:00

2013-09-01 03:25:00

2013-09-02 13:00:00

2013-09-02 13:06:59



SELECT 6