When running the same query multiple times, several questions come to mind:
Does the query always execute in the same amount of time?
If some executions are slower, what is the slowest execution time?
When did the slowest exectution happen?
What more can I find out about the slowest exectution?
All of this can be answered from data in Active Session History or ASH. The following query finds the maximum, minimum and average execution times in seconds as well as the time of the slowest execution which is given by start time and end time of the slowest exectuiton:
col av for 9999999
col mx for 9999999
col mn for 9999999
select
sql_id,
count(*),
round(min(delta),0) mn,
round(avg(delta),0) av,
round(max(delta),0) mx,
substr(max(times),12) max_run_time
from (
select
sql_id,
sql_exec_id,
max(delta) delta ,
-- lpad sets a fixed width on delta so it can be
-- stripped off above with substr
-- delta in "times" is just for sorting not displaying
lpad(round(max(delta),0),10) || ' ' ||
to_char(min(start_time),'YY-MM-DD HH24:MI:SS') || ' ' ||
to_char(max(end_time),'YY-MM-DD HH24:MI:SS') times
from ( select
sql_id,
sql_exec_id,
cast(sample_time as date) end_time,
cast(sql_exec_start as date) start_time,
((cast(sample_time as date)) -
(cast(sql_exec_start as date))) * (3600*24) delta
from
dba_hist_active_sess_history
where sql_exec_id is not null
)
group by sql_id,sql_exec_id
)
group by sql_id
having count(*) > 10
order by mx
/
SQL_ID COUNT(*) MN AV MX MAX_RUN_TIME
------------- ---------- -------- -------- -------- -----------------------------------
155vjqzjqp58f 27 0 115 786 11-04-11 07:39:47 11-04-11 07:41:20
7nf5917x3tq5x 113 0 129 791 11-04-11 01:03:19 11-03-02 04:16:09
asg774pz0kqga 11 11 225 799 11-04-14 12:20:10 11-03-02 12:18:58
1kf1jsykb1nk6 529 0 107 800 11-04-09 18:41:28 11-03-01 23:13:56
8rua4c9agcqkb 978 0 73 820 11-03-01 23:13:50 11-03-01 23:13:56
fdagtr1sdk8tn 313 0 242 841 11-04-08 21:30:31 11-04-08 21:30:38
7b5w34atn8q1h 124 0 25 898 11-03-07 20:53:17 11-03-07 20:53:23
9w7mbuv734tfy 11 30 509 954 11-04-14 09:00:55 11-03-02 04:27:33
88qxmg220db9s 23 4 357 1040 11-04-13 22:08:20 11-04-13 02:20:09
83ngzw213v0cs 302 1 207 1122 11-04-11 16:26:32 11-03-07 16:12:11
34cgtc9xkgxny 61 978 1163 1272 11-03-02 10:06:24 11-03-02 10:06:30
g5u58zpg0tuk8 97 1 62 1359 11-04-13 02:49:33 11-04-12 02:23:39
6tkqndn1tzf23 29 7 187 1370 11-04-13 06:56:43 11-03-02 06:56:54
g4wrnvdmf23b1 11 19 458 1397 11-04-14 12:22:28 11-03-02 12:21:19
bpkg6y9wvf717 31 0 189 1427 11-04-13 21:19:51 11-03-02 21:08:00
4d6m2q3ngjcv9 320 3 485 1701 11-04-10 18:00:54 11-03-01 23:10:55
882tp5sbq1tq5 17 39 367 1795 11-04-14 14:00:30 11-03-01 23:04:33
5k7vccwjr5ahd 2653 0 33 1963 11-04-12 09:06:08 11-03-01 23:10:15
44034jty9vnrg 19 2 188 1968 11-03-03 09:17:34 11-03-03 09:17:43
g9n69a23s3wxz 40 6 280 2009 11-04-08 13:47:23 11-03-03 09:37:38
ds8cz0fb8w147 161 13 274 2531 11-04-12 16:10:21 11-03-01 23:11:55
bzyny95313u12 114 0 47 2599 11-03-03 03:06:18 11-03-03 03:06:25
0fvrpk7476b7y 26 0 133 3068 11-03-07 07:57:56 11-03-07 07:58:00
1pjp66rxcj6tg 15 57 768 3106 11-04-09 17:25:21 11-03-07 08:58:26
8r5wuxk1dprhr 39 24 841 3510 11-04-14 14:00:47 11-03-02 09:54:37
0w5uu5kngyyty 21 0 442 3652 11-04-11 08:00:21 11-04-11 09:01:13
0hbv80w9ypy0n 161 0 1184 4089 11-04-12 22:26:09 11-03-02 04:36:15
71fwb4n6a92fv 49 30 677 4481 11-04-10 17:01:17 11-03-01 23:40:45
0bujgc94rg3fj 604 0 25 4929 11-04-08 10:53:34 11-04-08 12:15:43
64dqhdkkw63fd 1083 0 7 7147 11-03-07 04:01:01 11-03-07 06:00:08
990m08w8xav7s 591 0 52 7681 11-04-13 00:39:27 11-04-13 00:39:37
2n5369dsuvn5a 16 303 5727 10472 11-04-14 11:18:11 11-04-14 14:12:43
2spgk3k0f7quz 251 0 546 29607 11-04-12 12:11:47 11-04-12 12:11:48
36pd759xym9tc 12 1391 23862 37934 11-04-13 19:25:49 11-03-01 23:00:12
497wh6n7hu14f 49 0 5498 69438 11-04-12 19:01:17 11-04-13 12:03:54We can add a histogram of execution spread to the query
col 1 for 99999
col 2 for 99999
col 3 for 9999
col 4 for 999
col 5 for 99
col av for 99999.9
col ct for 99999
col mn for 999
col av for 99999.9
with pivot_data as (
select
sql_id,
ct,
mxdelta mx,
mndelta mn,
avdelta av,
-- high_boundary is set to maxdelta + 1 so that
-- nothing ends up in the overflow bucket
-- otherwise the max value ends up in the overflow bucket
width_bucket(delta,mndelta,mxdelta+1,5) as bucket ,
substr(times,12) max_run_time
from (
select
sql_id,
delta,
count(*) OVER (PARTITION BY sql_id) ct,
max(delta) OVER (PARTITION BY sql_id) mxdelta,
min(delta) OVER (PARTITION BY sql_id) mndelta,
avg(delta) OVER (PARTITION BY sql_id) avdelta,
max(times) OVER (PARTITION BY sql_id) times
from (
select
sql_id,
sql_exec_id,
max(delta) delta ,
-- lpad sets a fixed width on delta so it can be
-- stripped off above with substr
-- delta in "times" is just for sorting not displaying
lpad(round(max(delta),0),10) || ' ' ||
to_char(min(start_time),'YY-MM-DD HH24:MI:SS') || ' ' ||
to_char(max(end_time),'YY-MM-DD HH24:MI:SS') times
from ( select
sql_id,
sql_exec_id,
cast(sample_time as date) end_time,
cast(sql_exec_start as date) start_time,
((cast(sample_time as date)) -
(cast(sql_exec_start as date))) * (3600*24) delta
from
dba_hist_active_sess_history
where sql_exec_id is not null
)
group by sql_id,sql_exec_id
)
)
where ct > &min_repeat_executions_filter
)
select * from pivot_data
PIVOT ( count(*) FOR bucket IN (1,2,3,4,5))
order by mx,av;
/
SQL_ID CT MX MN AV MAX_RUN_TIME 1 2 3 4 5
------------- ------ ---------- ---- -------- ----------------------------------- ------ ------ ----- ---- ---
8rua4c9agcqkb 978 820 0 72.7 11-03-01 23:13:50 11-03-01 23:13:56 830 116 21 9 2
fdagtr1sdk8tn 313 841 0 241.8 11-04-08 21:30:31 11-04-08 21:30:38 194 45 0 0 74
7b5w34atn8q1h 124 898 0 24.8 11-03-07 20:53:17 11-03-07 20:53:23 122 0 0 0 2
83ngzw213v0cs 302 1122 1 207.5 11-04-11 16:26:32 11-03-07 16:12:11 200 68 21 6 7
g5u58zpg0tuk8 97 1359 1 62.1 11-04-13 02:49:33 11-04-12 02:23:39 92 3 1 0 1
4d6m2q3ngjcv9 320 1701 3 484.7 11-04-10 18:00:54 11-03-01 23:10:55 92 168 50 9 1
5k7vccwjr5ahd 2653 1963 0 33.4 11-04-12 09:06:08 11-03-01 23:10:15 2623 15 8 4 3
ds8cz0fb8w147 161 2531 13 273.8 11-04-12 16:10:21 11-03-01 23:11:55 136 18 5 1 1
bzyny95313u12 114 2599 0 46.5 11-03-03 03:06:18 11-03-03 03:06:25 113 0 0 0 1
0hbv80w9ypy0n 161 4089 0 1183.9 11-04-12 22:26:09 11-03-02 04:36:15 27 116 9 6 3
71fwb4n6a92fv 49 4481 30 676.9 11-04-10 17:01:17 11-03-01 23:40:45 38 6 2 2 1
0bujgc94rg3fj 604 4929 0 24.7 11-04-08 10:53:34 11-04-08 12:15:43 601 1 1 0 1
64dqhdkkw63fd 1083 7147 0 7.2 11-03-07 04:01:01 11-03-07 06:00:08 1082 0 0 0 1
990m08w8xav7s 591 7681 0 51.8 11-04-13 00:39:27 11-04-13 00:39:37 587 0 0 2 2
2spgk3k0f7quz 251 29607 0 546.1 11-04-12 12:11:47 11-04-12 12:11:48 247 2 0 0 2
497wh6n7hu14f 49 69438 0 5498.2 11-04-12 19:01:17 11-04-13 12:03:54 44 1 0 1 3Finally add the SQL_EXEC_ID of the longest running execution. This SQL_EXEC_ID can then be used to go look at the events in ASH for that particular execution
col 1 for 99999
col 2 for 99999
col 3 for 9999
col 4 for 999
col 5 for 99
col av for 99999
col ct for 99999
col mn for 999
col av for 99999.9
col longest_sql_exec_id for A10
WITH pivot_data AS (
SELECT
sql_id,
ct,
mxdelta mx,
mndelta mn,
round(avdelta) av,
WIDTH_BUCKET(delta_in_seconds,mndelta,mxdelta+.1,5) AS bucket ,
SUBSTR(times,12) max_run_time,
SUBSTR(longest_sql_exec_id, 12) longest_sql_exec_id
FROM (
SELECT
sql_id,
delta_in_seconds,
COUNT(*) OVER (PARTITION BY sql_id) ct,
MAX(delta_in_seconds) OVER (PARTITION BY sql_id) mxdelta,
MIN(delta_in_seconds) OVER (PARTITION BY sql_id) mndelta,
AVG(delta_in_seconds) OVER (PARTITION BY sql_id) avdelta,
MAX(times) OVER (PARTITION BY sql_id) times,
MAX(longest_sql_exec_id) OVER (PARTITION BY sql_id) longest_sql_exec_id
FROM (
SELECT
sql_id,
sql_exec_id,
MAX(delta_in_seconds) delta_in_seconds ,
LPAD(ROUND(MAX(delta_in_seconds),0),10) || ' ' ||
TO_CHAR(MIN(start_time),'YY-MM-DD HH24:MI:SS') || ' ' ||
TO_CHAR(MAX(end_time),'YY-MM-DD HH24:MI:SS') times,
LPAD(ROUND(MAX(delta_in_seconds),0),10) || ' ' ||
TO_CHAR(MAX(sql_exec_id)) longest_sql_exec_id
FROM ( SELECT
sql_id,
sql_exec_id,
CAST(sample_time AS DATE) end_time,
CAST(sql_exec_start AS DATE) start_time,
((CAST(sample_time AS DATE)) -
(CAST(sql_exec_start AS DATE))) * (3600*24) delta_in_seconds
FROM
dba_hist_active_sess_history
WHERE sql_exec_id IS NOT NULL
)
GROUP BY sql_id,sql_exec_id
)
)
where ct > &min_repeat_executions_filter
and mxdelta > &min_elapsed_time
)
SELECT * FROM pivot_data
PIVOT ( COUNT(*) FOR bucket IN (1,2,3,4,5))
ORDER BY mx DESC,av DESC
;
SQL_ID CT MX MN AV MAX_RUN_TIME LONGEST_SQ 1 2 3 4 5
------------- ------ ---------- ---- -------- ----------------------------------- ---------- ------ ------ ----- ---- ---
2spgk3k0f7quz 251 29607 0 546.0 11-04-12 12:11:47 11-04-12 20:25:14 16781748 247 2 0 0 2
990m08w8xav7s 591 7681 0 52.0 11-04-13 00:39:27 11-04-13 02:47:28 16786685 587 0 0 2 2
64dqhdkkw63fd 1083 7147 0 7.0 11-03-07 04:01:01 11-03-07 06:00:08 16777218 1082 0 0 0 1
0bujgc94rg3fj 604 4929 0 25.0 11-04-08 10:53:34 11-04-08 12:15:43 16814628 601 1 1 0 1
0hbv80w9ypy0n 161 4089 0 1184.0 11-03-02 04:36:10 11-04-12 23:34:18 16777290 27 116 9 6 3
bzyny95313u12 114 2599 0 47.0 11-03-03 03:06:18 11-03-03 03:49:37 16781191 113 0 0 0 1
ds8cz0fb8w147 161 2531 13 274.0 11-03-01 23:11:48 11-04-12 16:10:37 16777285 136 18 5 1 1
5k7vccwjr5ahd 2653 1963 0 33.0 11-03-01 23:10:12 11-04-12 09:06:12 16778244 2623 15 8 4 3
4d6m2q3ngjcv9 320 1701 3 485.0 11-03-01 23:10:53 11-04-10 18:01:26 16777261 92 168 50 9 1
g5u58zpg0tuk8 97 1359 1 62.0 11-04-12 02:23:37 11-04-13 02:51:09 16777217 92 3 1 0 1
34cgtc9xkgxny 61 1272 978 1163.0 11-03-02 10:06:24 11-03-02 10:27:36 16777250 4 4 14 30 9