Re: Missing rows under dba_hist_sqlstat

In the absence of further information I think Maris' observation is the correct one, and you would get a better handle on this by taking a snapshot of the session activity stats and session events for your test case.

However, I would be interested in seeing the justification Oracle support gave for their 'not a bug' conclusion.

Regards
Jonathan Lewis

On Wed, 25 Nov 2020 at 10:17, Cherif Ben Henda <cherif.benhenda_at_gmail.com> wrote:

> Hi All,
> During monitoring of PROD long running reporting...
> Oracle version 12.1/ optimizer_adaptive_features =false and optimizer_adaptive_plans
> =true, I identified a query taking more than 17 000 sec. The next day
> when I generated AWR covering its execution period, I found that this query
> had taken 2600 sec. I have checked dba_hist_sqlstat , there is only one
> row / one snap. The delta elapsed time was 2600 but the total elapsed time
> was exact / AWR report is based on delta columns. Under
> dba_hist_active_sess_history , I get the exact number of snap_id, in fact
> , there are many missing rows under dba_hist_sqlstat .
> I have identified the root cause. During these snapshots , we don't have a
> final execution plan ( it was a complex query with more than 14 tables), it
> was executed with an adaptive execution plan.
> I identified that this behavior happened with dozens of queries.
>
> I can not share with you the real issue , I succeed in reproducing it.
> I need to know if you have encountered a similar issue ? It seems like a
> bug
> Please find a test case, I have changed AWR snap duration to 5 min.
> https://livesql.oracle.com/apex/livesql/s/kv21hp90yyy8j142r41w00n3s
>
> I have opened an SR but they think it is not a bug ....
> --
> Cordialement,
> Cherif Ben Henda
>
>
>

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