zabbix=# SELECT
zabbix-#   to_timestamp(clock),
zabbix-#   COUNT(*)
zabbix-# FROM history_uint_p1525824000
zabbix-# WHERE itemid = 616241
zabbix-# GROUP BY 1
zabbix-# ORDER BY 1;
      to_timestamp      | count
------------------------+-------
 2018-05-09 02:00:54+02 |     1
 2018-05-09 02:01:56+02 |     1
 2018-05-09 02:02:58+02 |     1
 2018-05-09 02:04:00+02 |     1
 2018-05-09 02:05:02+02 |     1
 2018-05-09 02:06:04+02 |     1
 2018-05-09 02:07:06+02 |     1
 2018-05-09 02:08:08+02 |     1
 2018-05-09 02:09:09+02 |     1
 2018-05-09 02:10:18+02 |     1
 2018-05-09 02:11:21+02 |     1
 2018-05-09 02:12:23+02 |     1
 2018-05-09 02:13:25+02 |     1
 2018-05-09 02:14:26+02 |     1
 2018-05-09 02:15:28+02 |     1
 2018-05-09 02:16:30+02 |     1
 2018-05-09 02:17:31+02 |     1
 2018-05-09 02:18:33+02 |     1
 2018-05-09 02:19:35+02 |     1
 2018-05-09 02:20:37+02 |     1
 2018-05-09 02:21:39+02 |     1
 2018-05-09 02:22:40+02 |     1
 2018-05-09 02:23:41+02 |     1
 2018-05-09 02:24:42+02 |     1
 2018-05-09 02:25:43+02 |     1
 2018-05-09 02:26:45+02 |     1
 2018-05-09 02:27:46+02 |     1
 2018-05-09 02:28:47+02 |     1
 2018-05-09 02:29:49+02 |     1
 2018-05-09 02:30:50+02 |     1
 2018-05-09 02:31:51+02 |     1
 2018-05-09 02:32:53+02 |     1
 2018-05-09 02:33:54+02 |     1
 2018-05-09 02:34:55+02 |     1
 2018-05-09 02:35:57+02 |     1
 2018-05-09 02:36:58+02 |     1
 2018-05-09 02:37:59+02 |     1
 2018-05-09 02:39:00+02 |     1
 2018-05-09 02:40:01+02 |     1
 2018-05-09 02:41:03+02 |     1
 2018-05-09 02:42:04+02 |     1
 2018-05-09 02:43:05+02 |     1
 2018-05-09 02:44:06+02 |     1
 2018-05-09 02:45:07+02 |     1
 2018-05-09 02:46:09+02 |     1
 2018-05-09 02:47:10+02 |     1
 2018-05-09 02:48:11+02 |     1
 2018-05-09 02:49:12+02 |     1
 2018-05-09 02:50:13+02 |     1
 2018-05-09 02:51:15+02 |     1
 2018-05-09 02:52:16+02 |     1
 2018-05-09 02:53:17+02 |     1
 2018-05-09 02:54:18+02 |     1
 2018-05-09 02:55:19+02 |     1
 2018-05-09 02:56:21+02 |     1
 2018-05-09 02:57:22+02 |     1
 2018-05-09 02:58:23+02 |     1
 2018-05-09 02:59:24+02 |     1
 2018-05-09 03:00:26+02 |     1
 2018-05-09 03:01:28+02 |     1
 2018-05-09 03:02:44+02 |  2006
 2018-05-09 03:04:00+02 |  2006
 2018-05-09 03:05:50+02 |  2000
 2018-05-09 03:05:51+02 |     5
 2018-05-09 03:07:30+02 |  2005
 2018-05-09 03:09:10+02 |  2000
 2018-05-09 03:09:11+02 |     5
 2018-05-09 03:10:50+02 |  2004
 2018-05-09 03:10:51+02 |     1
 2018-05-09 03:12:30+02 |  2005
 2018-05-09 03:14:10+02 |  1999
 2018-05-09 03:14:11+02 |     5
 2018-05-09 03:15:50+02 |  2004
 2018-05-09 03:17:30+02 |  1999
 2018-05-09 03:17:31+02 |     5
 2018-05-09 03:19:10+02 |  2003
 2018-05-09 03:19:11+02 |     1
 2018-05-09 03:20:50+02 |  2004
 2018-05-09 03:22:30+02 |  1999
 2018-05-09 03:22:31+02 |     5
 2018-05-09 03:24:10+02 |  2004
 2018-05-09 03:25:50+02 |  1999
 2018-05-09 03:25:51+02 |     5
 2018-05-09 03:27:30+02 |  2003
 2018-05-09 03:27:31+02 |     1
 2018-05-09 03:29:10+02 |  2004
 2018-05-09 03:30:50+02 |  1999
 2018-05-09 03:30:51+02 |     5
 2018-05-09 03:32:30+02 |  2004
 2018-05-09 03:34:10+02 |  1999
 2018-05-09 03:34:11+02 |     5
 2018-05-09 03:35:50+02 |  2003
 2018-05-09 03:35:51+02 |     1
 2018-05-09 03:37:30+02 |  2004
 2018-05-09 03:39:10+02 |  1999
 2018-05-09 03:39:11+02 |     5
 2018-05-09 03:40:50+02 |  2004
 2018-05-09 03:42:30+02 |  1999
 2018-05-09 03:42:31+02 |     5
 2018-05-09 03:44:10+02 |  2003
 2018-05-09 03:44:11+02 |     1
 2018-05-09 03:45:50+02 |  2003
 2018-05-09 03:47:30+02 |  1998
 2018-05-09 03:47:31+02 |     5
 2018-05-09 03:49:10+02 |  2003
 2018-05-09 03:50:50+02 |  1998
 2018-05-09 03:50:51+02 |     5
 2018-05-09 03:52:30+02 |  2002
 2018-05-09 03:52:31+02 |     1
 2018-05-09 03:54:10+02 |  2003
 2018-05-09 03:55:50+02 |  1998
 2018-05-09 03:55:51+02 |     5
 2018-05-09 03:57:30+02 |  2003
 2018-05-09 03:59:10+02 |  1998
 2018-05-09 03:59:11+02 |     5
 2018-05-09 04:00:50+02 |  2003
 2018-05-09 04:00:51+02 |     1
 2018-05-09 04:01:59+02 |  2000
 2018-05-09 04:03:04+02 |  1995
 2018-05-09 04:04:12+02 |  1988
 2018-05-09 04:04:13+02 |     1
 2018-05-09 04:05:20+02 |  1981
 2018-05-09 04:06:25+02 |  1974
 2018-05-09 04:06:26+02 |     1
 2018-05-09 04:07:28+02 |  1966
 2018-05-09 04:07:29+02 |     3
 2018-05-09 04:08:34+02 |  1963
 2018-05-09 04:09:54+02 |  1957
 2018-05-09 04:09:55+02 |     1
 2018-05-09 04:11:01+02 |  1945
 2018-05-09 04:11:02+02 |     5
 2018-05-09 04:12:11+02 |  1945
 2018-05-09 04:13:17+02 |  1939
 2018-05-09 04:14:25+02 |  1933
 2018-05-09 04:14:26+02 |     1
 2018-05-09 04:15:29+02 |  1928
 2018-05-09 04:16:35+02 |  1924
 2018-05-09 04:17:43+02 |  1914
 2018-05-09 04:17:44+02 |     5
 2018-05-09 04:18:53+02 |  1914
(140 rows)

zabbix=#