A DBA_HIST_SQLSTAT query that I am very fond of

This is a quick post to share a SQL statement I use a lot at work. The query mines the AWR tables (beware the licence implications) for a specific SQL ID and date/time range and shows a few choice statistics for each snapshot period.


prompt enter start and end times in format DD-MON-YYYY [HH24:MI]
column sample_end format a21
select to_char(min(s.end_interval_time),'DD-MON-YYYY DY HH24:MI') sample_end
, q.sql_id
, q.plan_hash_value
, sum(q.EXECUTIONS_DELTA) executions
, round(sum(DISK_READS_delta)/greatest(sum(executions_delta),1),1) pio_per_exec
, round(sum(BUFFER_GETS_delta)/greatest(sum(executions_delta),1),1) lio_per_exec
, round((sum(ELAPSED_TIME_delta)/greatest(sum(executions_delta),1)/1000),1) msec_exec
from dba_hist_sqlstat q, dba_hist_snapshot s
where q.SQL_ID=trim('&sqlid.')
and s.snap_id = q.snap_id
and s.dbid = q.dbid
and s.instance_number = q.instance_number
and s.end_interval_time >= to_date(trim('&start_time.'),'dd-mon-yyyy hh24:mi')
and s.begin_interval_time <= to_date(trim('&end_time.'),'dd-mon-yyyy hh24:mi')
and substr(to_char(s.end_interval_time,'DD-MON-YYYY DY HH24:MI'),13,2) like '%&hr24_filter.%'
group by s.snap_id
, q.sql_id
, q.plan_hash_value
order by s.snap_id, q.sql_id, q.plan_hash_value

Nothing ground breaking and I’m sure many will have a similar script.

Below I have example output showing one of the scripts many successful outings, quite a dramatic plan change I’m sure you’ll agree.

SQL> @awrsql
enter start and end times in format DD-MON-YYYY [HH24:MI]
Enter value for sqlid: 1jjpo2i4b313g
Enter value for start_time: 15-NOV-2011
Enter value for end_time: 21-NOV-2011 13:00
Enter value for hr24_filter:

--------------------- ------------- --------------- ---------- ------------ ------------ ----------
15-nov-2011 TUE 08:00 1jjpo2i4b313g      3133159894     129629            0            5          0
16-nov-2011 WED 08:01 1jjpo2i4b313g      3133159894     115003            0            5         .1
17-nov-2011 THU 08:01 1jjpo2i4b313g      3133159894     115741            0            5          0
18-nov-2011 FRI 07:00 1jjpo2i4b313g      3133159894      30997            0            5         .1
18-nov-2011 FRI 08:00 1jjpo2i4b313g      3133159894      81034            0            5          0
21-nov-2011 MON 00:00 1jjpo2i4b313g       790865878         16     323091.6     323128.3    36905.8
21-nov-2011 MON 01:00 1jjpo2i4b313g       790865878         29     349676.2     349713.7    48387.2
21-nov-2011 MON 02:00 1jjpo2i4b313g       790865878         35     339474.6     339509.2    34057.7
21-nov-2011 MON 03:00 1jjpo2i4b313g       790865878         37     340934.6     340970.2    35899.4
21-nov-2011 MON 04:01 1jjpo2i4b313g       790865878         38     333469.1     333503.9    35450.8
21-nov-2011 MON 05:00 1jjpo2i4b313g       790865878         35     347559.3     347595.2    35231.8
21-nov-2011 MON 06:00 1jjpo2i4b313g       790865878         32     340224.8       340260    35208.3

I also like to use the query to track number of executions or LIO per execution over a longer time frame to see if either the frequency or individual impact of the SQL is changing over time. I can use the “hr24_filter” variable to do this, for example showing me all snapshots for hour “13” over a whole month.


7 thoughts on “A DBA_HIST_SQLSTAT query that I am very fond of

  1. It’s bit confusing to see the results of that report if one long execution (with single SQL_EXEC_ID) is spanned across multiple AWR snapshots 🙂

    • Hi Alex,
      You are correct, the executions column will show zero for snapshots in which the SQL did not complete. This can be confusing. I suspect there are similar and better variations out there – however this one still serves me well in most cases.

  2. Thanks for sharing the query.Can i know the reason behind using the function greatest in this query

    round(sum(DISK_READS_delta)/greatest(sum(executions_delta),1),1) pio_per_exec

    • Hi, thanks for the comment. The purpose of the GREATEST() function is to handle executions_delta = 0. This can happen if the query is still executing.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s