Re: Guidelines for avoid Bind Variable Peeking behavior

  • From: Roberto Veiga <roberto_veiga@xxxxxxxxx>
  • To: breitliw@xxxxxxxxxxxxx
  • Date: Mon, 1 Jun 2009 08:18:59 -0700 (PDT)

We are using Oracle 10 R2.
We did a test without histogram in a QA environment and we found a lot of 
performance problems in many processes. We had to fallback the change 
rapidly. I suppose that many statatements that use histogram to perform better 
start to use a worse plan.
The idea in identifying the Hash Join is because in a recent situation the plan 
was changed from Hash Join to Nested Loop and the performance falls down. There 
is nothing wrong with Hash Join! My idea is to use Hash Join and freeze this 
Thanks a lot.

--- Em dom, 31/5/09, Wolfgang Breitling <breitliw@xxxxxxxxxxxxx> escreveu:

De: Wolfgang Breitling <breitliw@xxxxxxxxxxxxx>
Assunto: Re: Guidelines for avoid Bind Variable Peeking behavior
Para: roberto_veiga@xxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Data: Domingo, 31 de Maio de 2009, 11:32

What Oracle version?

I am curious to know more how the situation became worse without 
histograms. The plans shouldn't change as often without histograms.
What is wrong with access plans using hash joins? I often prefer 
those over nested loops.

At 08:14 AM 5/31/2009, Roberto Veiga wrote:

>We have already tried to remove histograms and the situation become worse.
>-Access plan using Hash Join


Wolfgang Breitling
Centrex Consulting Corporation 


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