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

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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