PH13163: ZPARM FOR DISABLING CODE USED TO INCORPORATE UNCERTAINTY FACTOR IN PREDICATE FILTER FACTOR ESTIMATE FOR AC 19/06/11 PTF PECHANGE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• This APAR will change the default of zparm option QUERY ACCEL
  OPTION 9 introduced by APAR PH10758 to disable code
  used for incorporating the uncertainty factor
  (DSN_PREDICAT_TABLE.UNCERTAINTY) in the predicate
  filter factor estimate when there are insufficient
  statistics to determine whether to send a query to
  IBM Db2 Analytics Accelerator. Accelerator users who want
  to enable the uncertainty cost estimation will need to enable
  the new zparm to get this behaviour.
  Additional Keywords:
  ZSA45
  

Local fix

• No work around available
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All Db2 11 and Db2 12 for z/OS users                         *
  * of IBM Db2 Analytics Accelerator                             *
  * offload to execute queries with host                         *
  * variables or parameter markers.                              *
  * who have PH10758 (UI63176/UI63171)                           *
  * applied.                                                     *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * PH13163 is the PE-fixing APAR of                             *
  * PH10758 and the PTFs UI63176 (V11) and                       *
  * UI63171 (V12).                                               *
  *                                                              *
  * PH10758 introduced a new option, 9,                          *
  * to the Db2 subsystem parameter                               *
  * QUERY_ACCEL_OPTIONS. When the user                           *
  * specifies QUERY_ACCEL_OPTIONS with                           *
  * option 9, Db2 will not adjust the                            *
  * cost estimate even when 'uncertainty'                        *
  * is detected. By default,                                     *
  * QUERY_ACCEL_OPTIONS does not specify                         *
  * option 9.                                                    *
  *                                                              *
  * PH13163 will switch the 'costing'                            *
  * behavior when QUERY_ACCEL_OPTIONS                            *
  * has option 9 and when                                        *
  * QUERY_ACCEL_OPTIONS has the default                          *
  * value. When QUERY_ACCEL_OPTIONS                              *
  * has the default value, Db2 will not                          *
  * adjust the cost estimate even when                           *
  * 'uncertainty' is detected. When                              *
  * QUERY_ACCEL_OPTIONS specifies                                *
  * option 9, Db2 will adjust the cost                           *
  * estimate when 'uncertainty' is                               *
  * detected.                                                    *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply corrective PTF when available.                         *
  ****************************************************************
  PH13163 is the PE-fixing APAR of PH10758 and the PTFs UI63176
  and UI63171.
  
  PH10758 introduced a new option, 9, to the Db2 subsystem
  parameter QUERY_ACCEL_OPTIONS. When the user specifies
  QUERY_ACCEL_OPTIONS with option 9, Db2 will not adjust the
  cost estimate even when 'uncertainty' is detected. By default,
  QUERY_ACCEL_OPTIONS does not specify option 9.
  
  PH13163 will switch the 'costing' behavior when
  QUERY_ACCEL_OPTIONS has option 9 and when QUERY_ACCEL_OPTIONS
  has the default value. When QUERY_ACCEL_OPTIONS has the default
  value, Db2 will not adjust the cost estimate even when
  'uncertainty' is detected. When QUERY_ACCEL_OPTIONS specifies
  option 9, Db2 will adjust the cost estimate when 'uncertainty'
  is detected.
  

Problem conclusion

• PH13163 will switch the 'costing' behavior when
  QUERY_ACCEL_OPTIONS has option 9 and when QUERY_ACCEL_OPTIONS
  has the default value.
  
  IDAAV5R1/K IDAAV7R1/K SQLHOSTVAR SQLACCESSPATH
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  UI63856 UI63859

Modules/Macros

• DSNWZIFB DSNWZIFC DSNTIP8A DSNDQWPZ DSNTINST DSNDSPRM DSN6SPRM
  DSNXOGP
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RB10 PSY UI63859

     UP19/06/27 P F906 «

• RC10 PSY UI63856

     UP19/06/27 P F906 «

Fix is available

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