It took a bit of time to find because I'd remembered it incorrectly.
The thing I had in mind was about the decision to use (or not) serial direct
path reads for segment scans. It used to be based on the segment HWM, but
changed to the object level stats in 11.2, with a controlling parameter (Tanel
has a note
https://blog.tanelpoder.com/2012/09/03/optimizer-statistics-driven-direct-path-read-decision-for-full-table-scans-_direct_read_decision_statistics_driven/
) so not relevant in your case.
Regards
Jonathan Lewis
________________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx <oracle-l-bounce@xxxxxxxxxxxxx> on behalf
of Lothar Flatz <l.flatz@xxxxxxxxxx>
Sent: 17 June 2018 15:55
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: Explain Plan and Security
Hi Jonathan,
yes, we are currently thinking of such a solution. Would be great if you
could dig up the events.
An other approach would be a thin clone. But that would actually just
circumvent the words of the security statement, but violate the meaning.
Regards and thanks
Lothar
Am 17.06.2018 um 13:43 schrieb Jonathan Lewis:
Lothar,
Can you export the object definitions and object stats ? If so then you could
model and run the query to see if you can get the plan you want against the
production stats without seeing any production data (except the low, high and
histogram values). The rowsource execution stats would be meaningless, of
course, but the plan should match if you've got a matching environment.
You may have to set a couple of events to tell Oracle to use the object stats
instead of the segment HWM - but off the top of my head I can't give you an
immediate description of exactly what you'd have to do for that bit.
Regards
Jonathan Lewis
________________________________________
From: l.flatz@xxxxxxxxxx <l.flatz@xxxxxxxxxx>
Sent: 16 June 2018 14:28
To: martin.a.berger@xxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx; Jonathan Lewis
Subject: Re: Re: Re: Explain Plan and Security
Hi Martin,
that would not work. I am working for a service provider. The data is not
ours. We are by policy forbitten to run queries on prod other than against
the dictionary.
We must look for an other way. Maybe some instant clone would work.
Thanks
Lothar
----Ursprüngliche Nachricht----
Von : martin.a.berger@xxxxxxxxx
Datum : 15/06/2018 - 21:04 (CEST)
An : l.flatz@xxxxxxxxxx
Cc : jonathan@xxxxxxxxxxxxxxxxxx, oracle-l@xxxxxxxxxxxxx
Betreff : Re: Re: Explain Plan and Security
If I followed this thread right, there is nothing you can do than execute the
query. Everything else will generate different results.
Is there any chance you get permission to execute the query if you can
guarantee it only runs for "a very short time"?
E.g. a special (proxy) user with a very strict LOGICAL_READS_PER_SESSION
comes to my mind.
Or you add an additional filter with "where 1 =impossible_function" and your
"impossible_function" does an execute immediate "select 1/0 from dual".
More methods come to my mind, but I'm sure you get the idea.
The execution-trap can be tested in non-profit environment and so you might
convince your customer?
hth,
berx
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