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MF63539 - OSP-PERFM INDEX NOT USED DUE TO INCORRECT 'IS NOT NULL' EKR

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PTF ( Program Temporary Fixes ) Cover letter


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Abstract

OSP-PERFM INDEX NOT USED DUE TO INCORRECT 'IS NOT NULL' EKR


Pre/Co-Requisite PTF / Fix List

REQ  LICENSED           PTF/FIX  LEVEL

TYPE PROGRAM  RELEASE   NUMBER   MIN/MAX  OPTION
---- -------- --------- -------  -------  ------
CO   5770999  V7R3M0    MF62376   00/00    0000
CO   5770999  V7R3M0    MF61181   00/00    0000
CO   5770999  V7R3M0    MF61180   00/00    0000



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APAR Error Description / Circumvention

-----------------------------------------------
EKR was giving an estimate of 100% for the IsNotNull when
actually all rows are Null for a particular column. This invalid
estimate caused the desirable index to not be used.

CORRECTION FOR APAR MA46186 :
-----------------------------
The algorithm for calculating the number of non-NULL values for
a given key was found to have a bug that resulted in an estimate
of 100% when it should have been 0%.  The estimate problem is
specific to EKRs that are trying to determine the non-NULL
count.

CIRCUMVENTION FOR APAR MA46186 :
--------------------------------
None.


Activation Instructions


None.




Special Instructions


None.


Default Instructions

THIS PTF CAN BE APPLIED IMMEDIATE OR DELAYED.



Supersedes

PTF/FIX NO(S).  APAR TITLE LINE
--------------  ------------------------------------------------------------
   MF62379      LIC-DB-OTHER Internal Database Maintenance.
   MF62223      LIC-DB-OTHER-WAIT Queries may hang during optimization
   MF61949      LIC-DB-OTHER-UNPRED Internal Database Maintenance
   MF61395      LIC-DB-OTHER Internal database maintenance
   MF61179      LIC-DB-OTHER Enable key range estimate operations to return

Summary Information

System..............................i
Models..............................
Release.............................V7R3M0
Licensed Program...............5770999
APAR Fixed..........................View details for APAR MA46186
Superseded by:......................View fix details for PTF MF68793
Recompile...........................N
Library.............................QSYS
MRI Feature ........................NONE
Cum Level...........................C7283730


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Document Information

Modified date:
07 September 2021