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MF68748 - OSP-DB-OTHER-PERFM SQL HIGH CPU JOIN SKEW

PTF Cover Letter


PTF ( Program Temporary Fixes ) Cover letter


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Abstract

OSP-DB-OTHER-PERFM SQL HIGH CPU JOIN SKEW


Pre/Co-Requisite PTF / Fix List

REQ  LICENSED           PTF/FIX  LEVEL

TYPE PROGRAM  RELEASE   NUMBER   MIN/MAX  OPTION
---- -------- --------- -------  -------  ------
NONE



NOTICE:
-------
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APAR Error Description / Circumvention

-----------------------------------------------
The statistics engine provides a poor estimate for a join after
expecting skewed data on the join, despite having related local
predicates that should prevent the skewed value from joining.
The bad estimate results in a poorly performing plan.

CORRECTION FOR APAR MA49069 :
-----------------------------
In certain code paths, the statistics engine is using an
incorrect padding value for graphic unicode fields, which leads
to an invalid comparison between variables and a poor estimate.

CIRCUMVENTION FOR APAR MA49069 :
--------------------------------
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
--------------  ------------------------------------------------------------
     NONE

Summary Information

System..............................i
Models..............................
Release.............................V7R3M0
Licensed Program...............5770999
APAR Fixed..........................View details for APAR MA49069
Superseded by:......................
Recompile...........................N
Library.............................QSYS
MRI Feature ........................NONE
Cum Level...........................C1245730


IBM i Support

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Document Information

Modified date:
14 September 2021