CREATE TABLE tmp ( date timestamp UNIQUE NOT NULL , id_type integer NOT NULL ) ;

INSERT INTO tmp (date, id_type) VALUES ( '2017-01-10 07:19:21.0', 3 ), ( '2017-01-10 07:19:22.0', 3 ), ( '2017-01-10 07:19:23.1', 3 ), ( '2017-01-10 07:19:24.1', 3 ), ( '2017-01-10 07:19:25.0', 3 ), ( '2017-01-10 07:19:26.0', 5 ), ( '2017-01-10 07:19:27.1', 3 ), ( '2017-01-10 07:19:28.0', 5 ), ( '2017-01-10 07:19:29.0', 5 ), ( '2017-01-10 07:19:30.1', 3 ), ( '2017-01-10 07:19:31.0', 5 ), ( '2017-01-10 07:19:32.0', 3 ), ( '2017-01-10 07:19:33.1', 5 ), ( '2017-01-10 07:19:35.0', 5 ), ( '2017-01-10 07:19:36.1', 5 ), ( '2017-01-10 07:19:37.1', 5 );

INSERT INTO tmp(date, id_type) SELECT date + interval '1 day' * g, id_type FROM tmp, generate_series(1,8000) g;

VACUUM ANALYZE tmp;

CREATE OR REPLACE FUNCTION f_tmp_groups() RETURNS TABLE (id_type int, grp_begin timestamp, grp_end timestamp) AS $func$ DECLARE _row tmp; -- use table type for row variable BEGIN FOR _row IN TABLE tmp ORDER BY date -- add more columns to make order deterministic LOOP CASE _row.id_type = id_type WHEN TRUE THEN -- same group continues grp_end := _row.date; -- remember last date so far WHEN FALSE THEN -- next group starts RETURN NEXT; -- return result for last group id_type := _row.id_type; grp_begin := _row.date; grp_end := _row.date; ELSE -- NULL for 1st row id_type := _row.id_type; -- remember row data for starters grp_begin := _row.date; grp_end := _row.date; END CASE; END LOOP; RETURN NEXT; -- return last result row END $func$ LANGUAGE plpgsql;

-- 1. EXPLAIN (ANALYZE, TIMING OFF) SELECT id_type , min(date) AS begin , max(date) AS end FROM ( SELECT date, id_type, count(step OR NULL) OVER (ORDER BY date) AS grp FROM ( SELECT date, id_type , lag(id_type) OVER (ORDER BY date) <> id_type AS step FROM tmp ) sub1 ) sub2 GROUP BY id_type, grp ORDER BY min(date);

-- 2. EXPLAIN (ANALYZE, TIMING OFF) SELECT min(date) AS begin , max(date) AS end , id_type FROM ( SELECT date, id_type , row_number() OVER (ORDER BY date) - row_number() OVER (PARTITION BY id_type ORDER BY date) AS grp FROM tmp ) sub GROUP BY id_type, grp ORDER BY min(date);

-- 3. EXPLAIN (ANALYZE, TIMING OFF) SELECT * FROM f_tmp_groups();