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MF64755 - OSP-PERFM RCTE QUERY CAUSING HIGH CPU UTILIZATION IN DATABAS

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PTF ( Program Temporary Fixes ) Cover letter


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Abstract

OSP-PERFM RCTE QUERY CAUSING HIGH CPU UTILIZATION IN DATABAS


Pre/Co-Requisite PTF / Fix List

REQ  LICENSED           PTF/FIX  LEVEL

TYPE PROGRAM  RELEASE   NUMBER   MIN/MAX  OPTION
---- -------- --------- -------  -------  ------
PRE  5770999  V7R3M0    MF64754   00/00    0000



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APAR Error Description / Circumvention

-----------------------------------------------
Complex RCTE query would intermittently not finish. The issue is
due to the optimizer attempting to validate statistics, and
never coming out of that re-validation. This caused that job to
utilize CPU continuously while it was attempting to re-validate
these stats.

CORRECTION FOR APAR MA46786 :
-----------------------------
The statistics engine was having difficulties recognizing which
levels of RCTE recursion had already been evaluated, thus it was
continuously re-calculating and looping through the levels many
times.  As a result, estimate validation was taking a very long
time when trying to determine if a cached plan could be re-used.

CIRCUMVENTION FOR APAR MA46786 :
--------------------------------
None.


Activation Instructions


None.




Special Instructions


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THIS PTF CAN BE APPLIED IMMEDIATE OR DELAYED.



Supersedes

PTF/FIX NO(S).  APAR TITLE LINE
--------------  ------------------------------------------------------------
   MF63896      OSP-OTHER-PERFM PSEUDO_OPEN_CHECK_HOST_VARS QAQQINI SETTING
   MF62677      LIC-DB-OTHER-PERFM SQL STATEMENT CONTAINING A RCTE IS RE-OPT

Summary Information

System..............................i
Models..............................
Release.............................V7R3M0
Licensed Program...............5770999
APAR Fixed..........................View details for APAR MA46786
Superseded by:......................
Recompile...........................N
Library.............................QSYS
MRI Feature ........................NONE
Cum Level...........................C8242730


System i Support

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Document Information

Modified date:
08 May 2018