Re: RE: query slow in 9i, but not slow in 8i

  • From: Mark Richard <mrichard@xxxxxxxxxxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Tue, 2 Mar 2004 15:14:17 +1100


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I am unfortunately speaking from heresay, however I heard once that having
histograms all over the place can slow down parsing as they have to be
inspected.  I was left with the impression that unless the data is skewed
enough to warrant a histogram then there actually is a negative cost
associated with having too many histograms.

Surely someone on this list can either support me or shoot me down on this
one?



                                                                                
                                                     
                      Wolfgang Breitling                                        
                                                     
                      <breitliw@centrexc        To:       
oracle-l@xxxxxxxxxxxxx                                                     
                      c.com>                    cc:                             
                                                     
                      Sent by:                  Subject:  Re: RE: query slow in 
9i, but not slow in 8i                               
                      oracle-l-bounce@fr                                        
                                                     
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                      02/03/2004 12:04                                          
                                                     
                      Please respond to                                         
                                                     
                      oracle-l                                                  
                                                     
                                                                                
                                                     
                                                                                
                                                     




As long as it works for you - nothing.

However - to quote myself:
"Histograms are like drugs –  An overdose [of histograms] can kill
[performance]."

And like drugs, the practice may seem harmless and you get used to it,
until one day ...

"It seems easier just to ..." is never a good enough reason for me to do -
or not do - something.

At 04:14 PM 3/1/2004, you wrote:
>If you have the window and use monitoring what is wrong with getting
>histograms on every table? I'm doing all new development with new queries
>getting developed everyday. It seems easier just to put histograms on
>everything. I have the window to do this overnight and will have it when
we
>go live?

Wolfgang Breitling
Oracle7, 8, 8i, 9i OCP DBA
Centrex Consulting Corporation
http://www.centrexcc.com

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