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PM54681: DB2 MAY CHOOSE AN INEFFECTIVE ACCESS PATH FOR THE PREDICATES REFERENCING A COLUMN WITH FREQUENCY, HISTOGRAM.

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APAR status

  • Closed as program error.

Error description

  • DB2 may choose an ineffective access path for the
predicates referencing a column with frequency, histogram.

Local fix

  • N/A

Problem summary

  • ****************************************************************
* USERS AFFECTED: DB2 for z/OS users with queries containing   *
*                 predicates on columns where frequency or     *
*                 histogram statistics have been collected.    *
****************************************************************
* PROBLEM DESCRIPTION: DB2 may choose an inefficient access    *
*                      path for query with predicates          *
*                      referencing a column or columns where   *
*                      frequency or histogram statistics have  *
*                      been collected.                         *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
DB2 may choose an inefficient access path for query with
predicates referencing a column where frequency or histogram
statistics have been collected.  When the problem occurs, it
might result in a poorly performing access path being selected
by the optimizer.

Problem conclusion

  • The problems mentioned above are fixed so that DB2 will not
give incorrect filter factor estimation in that situation.

ADDITIONAL KEYWORDS:

SQLACCESSPATH SQLPERFORMANCE

Temporary fix

  • 



Comments


    

  • 



APAR Information




    

  • APAR number
    PM54681
    • 

  • Reported component name
    DB2 OS/390 & Z/
    • 

  • Reported component ID
    5740XYR00
    • 

  • Reported release
    A10
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    YesHIPER
    • 

  • Special Attention
    NoSpecatt
    • 

  • Submitted date
    2011-12-20
    • 

  • Closed date
    2012-01-13
    • 

  • Last modified date
    2012-02-02
    • 





    

  • APAR is sysrouted FROM one or more of the following:
    

    • 

  • APAR is sysrouted TO one or more of the following:
    

    
UK75450
    

    • 



Modules/Macros


    

  • DSNXODFB DSNXODFE DSNXODFR DSNXODFT DSNXODFX

    



Fix information


    

  • Fixed component name
    DB2 OS/390 & Z/
    • 

  • Fixed component ID
    5740XYR00
    • 



Applicable component levels


    

  • RA10  PSY  UK75450
       UP12/01/31  P  F201
    • 



Fix is available


    

  • Select the PTF appropriate for your component level.
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Document Information


            

            


                        

            Modified date:
            

            02 February 2012
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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