Re: How to avoid using the execution plan with parallel on oracle rac 19.13?
Date: Wed, 31 May 2023 13:12:45 +0800
Message-ID: <CABpiuuRHm8wE3a4X=Lm4js7jQiksr_DsZ3r7Z_EvAocd6wFJ4A_at_mail.gmail.com>
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
>
>
>
-- http://www.freelists.org/webpage/oracle-lReceived on Wed May 31 2023 - 07:12:45 CEST
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