CREATE OR REPLACE FUNCTION generate_histogram()
    RETURNS TABLE (
    range TEXT, freq INT, bar TEXT
  )  AS $$
Declare
    bucket_id integer;
    query_id text;
BEGIN
    select bucket into bucket_id from pg_stat_monitor order by calls desc limit 1;
    select queryid into query_id from pg_stat_monitor order by calls desc limit 1;
    --RAISE INFO 'bucket_id %', bucket_id;
    --RAISE INFO 'query_id %', query_id;
    return query
    SELECT * FROM histogram(bucket_id, query_id) AS a(range TEXT, freq INT, bar TEXT);
END;
$$ LANGUAGE plpgsql;
CREATE OR REPLACE FUNCTION run_pg_sleep(INTEGER) RETURNS VOID AS $$
DECLARE
    loops ALIAS FOR $1;
BEGIN
    FOR i IN 1..loops LOOP
	--RAISE INFO 'Current timestamp: %', timeofday()::TIMESTAMP;
	RAISE INFO 'Sleep % seconds', i;
	PERFORM pg_sleep(i);
    END LOOP;
END;
$$ LANGUAGE 'plpgsql' STRICT;
CREATE EXTENSION pg_stat_monitor;
SELECT pg_stat_monitor_reset();
 pg_stat_monitor_reset 
-----------------------
 
(1 row)

Set pg_stat_monitor.pgsm_track='all';
select run_pg_sleep(5);
INFO:  Sleep 1 seconds
INFO:  Sleep 2 seconds
INFO:  Sleep 3 seconds
INFO:  Sleep 4 seconds
INFO:  Sleep 5 seconds
 run_pg_sleep 
--------------
 
(1 row)

SELECT substr(query, 0,50) as query, calls, resp_calls FROM pg_stat_monitor ORDER BY query COLLATE "C";
                       query                       | calls |      resp_calls       
---------------------------------------------------+-------+-----------------------
 SELECT pg_sleep(i)                                |     5 | {0,0,0,0,0,0,3,2,0,0}
 SELECT pg_stat_monitor_reset()                    |     1 | {1,0,0,0,0,0,0,0,0,0}
 SELECT substr(query, $1,$2) as query, calls, resp |     1 | {1,0,0,0,0,0,0,0,0,0}
 Set pg_stat_monitor.pgsm_track='all'              |     1 | {1,0,0,0,0,0,0,0,0,0}
 select run_pg_sleep($1)                           |     1 | {0,0,0,0,0,0,0,0,1,0}
(5 rows)

select * from generate_histogram();
       range        | freq |              bar               
--------------------+------+--------------------------------
 (0 - 3)}           |    0 | 
  (3 - 10)}         |    0 | 
  (10 - 31)}        |    0 | 
  (31 - 100)}       |    0 | 
  (100 - 316)}      |    0 | 
  (316 - 1000)}     |    0 | 
  (1000 - 3162)}    |    3 | ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  (3162 - 10000)}   |    2 | ■■■■■■■■■■■■■■■■■■■■
  (10000 - 31622)}  |    0 | 
  (31622 - 100000)} |    0 | 
(10 rows)

DROP EXTENSION pg_stat_monitor;