Re: Can we have pending system statistics in 11g /RC for plan switch between NL & HJ

The most important item in the test database is missing: SREADTIM. That defines the price of doing a single block read, for instance an index read.

On 09/27/2018 11:51 AM, kunwar singh wrote:
> PROD:
>
> PNAME                  PVAL1
> ------------------------------ ----------
> CPUSPEEDNW                  1460
> IOSEEKTIM                     10
> IOTFRSPEED                  4096
> SREADTIM                  .019
> MREADTIM                  .146
> CPUSPEED                  1616
> MBRC
> MAXTHR            1653342432
> SLAVETHR               5633100
>
> TEST:
>
> PNAME                  PVAL1
> ------------------------------ ----------
> CPUSPEEDNW                  1753
> IOSEEKTIM                     10
> IOTFRSPEED                  4096
> SREADTIM
> MREADTIM                  .003
> CPUSPEED                  1754
> MBRC
> MAXTHR             321806336
> SLAVETHR              19452160
>
> On Thu, Sep 27, 2018 at 3:43 AM Harmandeep Singh <singh.bedi_at_gmail.com
> <mailto:singh.bedi_at_gmail.com>> wrote:
>
> Please get the result of below sql from both dbs
>
> select * from sys.aux_stats$;
>
> Regards,
> Harman
>
> On Wed, Sep 26, 2018 at 2:25 PM kunwar singh
> <krishsingh.111_at_gmail.com <mailto:krishsingh.111_at_gmail.com>> wrote:
>
> Hi everyone,
> I am having a hard time in debugging the RC for many plan
> differences between 2 DBs where the only difference is in
> system statistics (especially MREADTIM and CPUSPEED) . All
> other DB parameters are same.
>
> Bad plans (using NL joins) in PROD. Good plan( Hash joins) in test
>
> I read this article from Franck and one more where he mention
> an existing bug opened.
> https://blog.dbi-services.com/can-you-have-pending-system-statistics/
>
> Is there any workaround to getting /pending system statistics
> /working in 11.2.0.4 in order to check if that will
> resolve the problem? I do not want to cause widespread issues 
> by importing system statistics when i know ( per the above
> blog) that system statistics wont remain pending!
>
> Or would you suggest any other structured approach in order to
> find the problem? I am not good at all in reading 10053 trace .
> --
> Cheers,
> Kunwar
>
>
>
> --
> Cheers,
> Kunwar

-- 
Mladen Gogala
Database Consultant
Tel: (347) 321-1217


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