Re: Tuning Advice

From: Chris Taylor <christopherdtaylor1994_at_gmail.com>
Date: Fri, 27 Apr 2018 11:22:08 -0500
Message-ID: <CAP79kiRrK=zzktv4OFwm4t=N8wNkvJ7+++1cBR0TgWdcpHtcHw_at_mail.gmail.com>

Questions:

1. Does the inserted table have constraints - especially FK contraints back to a parent table?
2. Is there anything unusual about the table being inserted such as being an IOT , partitioned etc?

Tips:

1. Execute your SELECT sql (without the INSERT) and then immediately execute :

select * from table(dbms_xplan.display_cursor(null,null,'ADVANCED IOSTATS LAST'))
/

From that output you can grab everything under the OUTLINE section - it's a big hint and you can add that to your SELECT statement and use it in your insert.
For example let's say your output under OUTLINE DATA looks something like:

  /*+

      BEGIN_OUTLINE_DATA
      IGNORE_OPTIM_EMBEDDED_HINTS
      OPTIMIZER_FEATURES_ENABLE('12.1.0.2')
      DB_VERSION('12.1.0.2')
      OPT_PARAM('_optim_peek_user_binds' 'false')
      OPT_PARAM('optimizer_dynamic_sampling' 0)
      OPT_PARAM('_bloom_filter_enabled' 'false')
      OPT_PARAM('_optimizer_use_feedback' 'false')
      OPT_PARAM('_px_adaptive_dist_method' 'off')
      OPT_PARAM('_optimizer_dsdir_usage_control' 0)
      OPT_PARAM('_optimizer_adaptive_plans' 'false')
      OPT_PARAM('_optimizer_strans_adaptive_pruning' 'false')
      OPT_PARAM('_optimizer_gather_feedback' 'false')
      OPT_PARAM('_optimizer_aggr_groupby_elim' 'false')
      OPT_PARAM('_optimizer_reduce_groupby_key' 'false')
      OPT_PARAM('_optimizer_nlj_hj_adaptive_join' 'false')
      OPT_PARAM('_fix_control' '20355502:8')
      ALL_ROWS
      OUTLINE_LEAF(_at_"SEL$1")
      FULL(_at_"SEL$1" "N"_at_"SEL$1")
      END_OUTLINE_DATA

  */

Then your INSERT would become:

INSERT into my_table (col1, col2, col3, colN) SELECT /*+

      BEGIN_OUTLINE_DATA
      IGNORE_OPTIM_EMBEDDED_HINTS
      OPTIMIZER_FEATURES_ENABLE('12.1.0.2')
      DB_VERSION('12.1.0.2')
      OPT_PARAM('_optim_peek_user_binds' 'false')
      OPT_PARAM('optimizer_dynamic_sampling' 0)
      OPT_PARAM('_bloom_filter_enabled' 'false')
      OPT_PARAM('_optimizer_use_feedback' 'false')
      OPT_PARAM('_px_adaptive_dist_method' 'off')
      OPT_PARAM('_optimizer_dsdir_usage_control' 0)
      OPT_PARAM('_optimizer_adaptive_plans' 'false')
      OPT_PARAM('_optimizer_strans_adaptive_pruning' 'false')
      OPT_PARAM('_optimizer_gather_feedback' 'false')
      OPT_PARAM('_optimizer_aggr_groupby_elim' 'false')
      OPT_PARAM('_optimizer_reduce_groupby_key' 'false')
      OPT_PARAM('_optimizer_nlj_hj_adaptive_join' 'false')
      OPT_PARAM('_fix_control' '20355502:8')
      ALL_ROWS
      OUTLINE_LEAF(_at_"SEL$1")
      FULL(_at_"SEL$1" "N"_at_"SEL$1")
      END_OUTLINE_DATA

  */
col1, col2, col3, colN from my_other_table;

HTH
Chris

On Fri, Apr 27, 2018 at 10:50 AM, Sheehan, Jeremy <JEREMY.SHEEHAN_at_fpl.com> wrote:

> Hello Gurus,
>
>
>
> Oracle 12.1.0.2
>
> AIX 7.1
>
>
>
> I have a query that runs fairly well. Takes about 8 minutes to run,
> nothing terrible about it (no huge FTS, joins seem to be in place
> correctly). When I try to do an insert into TABLE as SELECT, it picks a
> completely different execution plan and never finishes. The really odd
> thing is that it works great when using CTAS or initial creation of a MV.
>
>
>
> Any suggestion on how I can have the optimizer not use a specific
> execution plan or any session level parameters that would have it use a
> different execution plan?
>
>
>
> Thanks in advance!
>
>
>
> Jeremy
>

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Received on Fri Apr 27 2018 - 18:22:08 CEST