PI11801: TOTAL ESTIMATED COST FOR A QUERY WITH A COMMON TABLE EXPRESSION (CTE) MAY BE INACCURATE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• For example, the total cost of the query did not accurately
  reflect the cost of executing the common table expression.  This
  could cause the total estimated cost of the query to be too low
  which could impact IDAA offloading or the predictive governor
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: DB2 11 for z/OS users of common table        *
  *                 expressions (CTEs).                          *
  ****************************************************************
  * PROBLEM DESCRIPTION: The total cost of a query with common   *
  *                      table expressions may be                *
  *                      underestimated.                         *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The total cost of a query with common table expressions may be
  underestimated as the cost of materializing common table
  expressions may not be included in the total cost. This problem
  may prevent a query with common table expressions from being
  offloaded to IBM DB2 Analytics Accelerator.
  
  The cost estimation of a query can be checked in
  DSN_STATEMNT_TABLE and DSN_DETCOST_TABLE after EXPLAINing a
  query.
  
  Additional Keywords:
  SQLACCESSPATH  SQLEXPLAIN  SQLCTE  IDAAV2R1/K  IDAAV3R1/K
  IDAAV4R1/K  DSN_STATEMNT_TABLE  DSN_DETCOST_TABLE
  

Problem conclusion

• Code has been modified to include the cost of materializing
  common table expressions in the total cost.
  

Temporary fix

Comments

APAR Information

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

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

  UI17501

Modules/Macros

• DSNXOTS
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RB10 PSY UI17501

     UP14/05/14 P F405

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.