Re: How to avoid using the execution plan with parallel on oracle rac 19.13?

And also the ADDM report in attachment - not sure how much size Oracle-L allowed the max size is, because SQL monitor report has only 10 KB but has 65 KB for a screenshot Oracle-L is forbidden to send (probably the max allowed size is 50 KB).

Quanwen Zhao <quanwenzhao_at_gmail.com> 于2023年5月31日周三 13:12写道：

> Hello Lothar,
>
> You can see the attachment I've uploaded in - it's a SQL monitor report
> generated by tool sqlhc.
>
> Lothar Flatz <l.flatz_at_bluewin.ch> 于2023年5月30日周二 17:53写道：
>
>> Hi,
>>
>> unfortunately there is no attachment in this mail.
>> A query of the v$ views is often one of the most difficult to tune.
>> Statistics are often incorrect, estimates are wrong and there is a
>> tendency by the optimizers to generate inefficient plans.
>> The general strategy is break the query into smaller parts useing WITH
>> .. /*+ materialize */ to prohibit view merging.
>> Even if you read the best books, you would be still a novice with tuning.
>> Yo would need somebody experienced to help you.
>>
>> Thanks
>>
>> Lothar
>> Am 28.05.2023 um 07:23 schrieb Mladen Gogala:
>>
>>
>> On 5/27/23 23:10, Quanwen Zhao wrote:
>>
>>
>> If so, how to optimize the sql to reduce I/O and query time? By the way
>> I've generated the *SQL monitor* and *ADDM reports* for this sql and
>> uploaded them in attachment.
>>
>>
>> Use the Force Quanwen, use the Force. Just kidding. The Force emits CO2
>> and that's bad for the environment. Greta wouldn't want you to use to
>> Force.
>>
>> What you are asking is how to become a DBA. The best way is to join a
>> large organization which has several levels of DBA personnel and have a
>> senior DBA mentor you. I would seriously advise Tom Kyte's "Expert Oracle
>> Arachitecture", the "Core DBA" book by Jonathan Lewis and, mandatory, Cary
>> Millisap's: "Optimizing Oracle for Performance". The last book is written
>> in time of Oracle 8i, but is one of the philosophically most important
>> bookse ever written about Oracle. This is, of course, just for the
>> starters. After that, there is Christian Antognini's Oracle tuning book and
>> many others. Being a DBA is a life long process. A good way to start is to
>> figure out the air speed velocity of an unladen swallow. One has to know
>> these things when you're a DBA
>>
>>
>> --
>> Mladen Gogala
>> Database Consultantu
>> Tel: (347) 321-1217
>> https://dbwhisperer.wordpress.com
>>
>>
>>

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