— Purpose: Find statements that have significantly different elapsed time than before.
— Usage: This scripts prompts for four values.
—
— days_ago: how long ago was the change made that you wish to evaluate
— (this could easily be changed to a snap_id for more precision)
—
— min_stddev: the minimum “normalized” standard deviation between plans
— (the default is 2 – which means twice as fast/slow)
—
— min_etime: only include statements that have an avg. etime > this value
— (the default is .1 second)
—
—
— faster_slower: a flag to indicate if you want only Faster or Slower SQL
— (the default is both – use S% for slower and F% for faster)
—
— Description: This scripts attempts to find statements with significantly different
— average elapsed times per execution. It uses AWR data and computes a
— normalized standard deviation between the average elapsed time per
— execution before and after the date specified by the days_ago parameter.
—
— The ouput includes the following:
—
— SQL_ID – the sql_id of a statement that is in the shared pool (v$sqlarea)
—
— EXECS – the total number of executions in the AWR tables
—
— AVG_ETIME_BEFORE – the average elapsed time per execution before the REFERENCE_TIME
—
— AVG_ETIME_AFTER – the average elapsed time per execution after the REFERENCE_TIME
—
— NORM_STDDEV – this is a normalized standard deviation (i.e. how many times slower/faster is it now)
————————————————————————————————————————–
accept days_ago –
prompt ‘Enter Days ago: ‘ –
default ‘1’
set lines 155
col execs for 999,999,999
col before_etime for 999,990.99
col after_etime for 999,990.99
col before_avg_etime for 999,990.99 head AVG_ETIME_BEFORE
col after_avg_etime for 999,990.99 head AVG_ETIME_AFTER
col min_etime for 999,990.99
col max_etime for 999,990.99
col avg_etime for 999,990.999
col avg_lio for 999,999,990.9
col norm_stddev for 999,990.9999
col begin_interval_time for a30
col node for 99999
break on plan_hash_value on startup_time skip 1
select * from (
select sql_id, execs, before_avg_etime, after_avg_etime, norm_stddev,
case when to_number(before_avg_etime) < to_number(after_avg_etime) then ‘Slower’ else ‘Faster’ end result
— select *
from (
select sql_id, sum(execs) execs, sum(before_execs) before_execs, sum(after_execs) after_execs,
sum(before_avg_etime) before_avg_etime, sum(after_avg_etime) after_avg_etime,
min(avg_etime) min_etime, max(avg_etime) max_etime, stddev_etime/min(avg_etime) norm_stddev,
case when sum(before_avg_etime) > sum(after_avg_etime) then ‘Slower’ else ‘Faster’ end better_or_worse
from (
select sql_id,
period_flag,
execs,
avg_etime,
stddev_etime,
case when period_flag = ‘Before’ then execs else 0 end before_execs,
case when period_flag = ‘Before’ then avg_etime else 0 end before_avg_etime,
case when period_flag = ‘After’ then execs else 0 end after_execs,
case when period_flag = ‘After’ then avg_etime else 0 end after_avg_etime
from (
select sql_id, period_flag, execs, avg_etime,
stddev(avg_etime) over (partition by sql_id) stddev_etime
from (
select sql_id, period_flag, sum(execs) execs, sum(etime)/sum(decode(execs,0,1,execs)) avg_etime from (
select sql_id, ‘Before’ period_flag,
nvl(executions_delta,0) execs,
(elapsed_time_delta)/1000000 etime
— sum((buffer_gets_delta/decode(nvl(buffer_gets_delta,0),0,1,executions_delta))) avg_lio
from DBA_HIST_SQLSTAT S, DBA_HIST_SNAPSHOT SS
where ss.snap_id = S.snap_id
and ss.instance_number = S.instance_number
and executions_delta > 0
and elapsed_time_delta > 0
and ss.begin_interval_time <= sysdate-&&days_ago
union
select sql_id, ‘After’ period_flag,
nvl(executions_delta,0) execs,
(elapsed_time_delta)/1000000 etime
— (elapsed_time_delta)/decode(nvl(executions_delta,0),0,1,executions_delta)/1000000 avg_etime
— sum((buffer_gets_delta/decode(nvl(buffer_gets_delta,0),0,1,executions_delta))) avg_lio
from DBA_HIST_SQLSTAT S, DBA_HIST_SNAPSHOT SS
where ss.snap_id = S.snap_id
and ss.instance_number = S.instance_number
and executions_delta > 0
and elapsed_time_delta > 0
and ss.begin_interval_time > sysdate-&&days_ago
— and s.snap_id > 7113
)
group by sql_id, period_flag
)
)
)
group by sql_id, stddev_etime
)
where norm_stddev > nvl(to_number(‘&min_stddev’),2)
and max_etime > nvl(to_number(‘&min_etime’),.1)
)
where result like nvl(‘&Faster_Slower’,result)
order by norm_stddev
/
