PH16694: NO ROW IN DSN_QUERYINFO_TABLE FOR QINAME1 = 'ACCELMDL' WHEN DB2 ZPARM ACCELMODEL=YES, QUERY ACCELERATION ¬= NONE, EXPLAIN USED

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Db2 EXPLAIN table DSN_QUERYINFO_TABLE does not contain expected
  row for SQL query where column QINAME1 contains value 'ACCELMDL'
  when EXPLAIN is used for the query and ,
   - Db2 subsystem parameter ACCELMODEL = YES
     (to request Accelerator modeling for an SQL query), and
   - QUERY ACCELERATION ¬= NONE
     (to request query acceleration)
  .
  A DSN_QUERYINFO_TABLE row where column QINAME1 = ACCELMDL is
  expected for the SQL query in this scenario.
  .
  Additional search keywords:  IDAAV5R1/K IDAAV7R1/K
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All Db2 12 for z/OS users of QUERY                           *
  * ACCELERATION, Accelerator modeling using                     *
  * Db2 subsystem parameter ACCELMODEL=YES, and                  *
  * EXPLAIN is used for a dynamic query.                         *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * When Db2 subsystem parm ACCELMODEL=YES                       *
  * (to request Accelerator modeling for                         *
  * SQL queries), Db2 EXPLAIN table                              *
  * DSN_QUERYINFO_TABLE does not contain                         *
  * expected row for a dynamic SQL query                         *
  * where column QINAME1 = 'ACCELMDL' when                       *
  * EXPLAIN is used for the query and both                       *
  * of the following conditions are true:                        *
  * 1. QUERY ACCELERATION ^= NONE to                             *
  * request query acceleration, and                              *
  * 2. there are no Accelerators currently                       *
  * active or STARTed in Db2z.                                   *
  * .                                                            *
  * A DSN_QUERYINFO_TABLE row where column                       *
  * QINAME1 = 'ACCELMDL' is expected for                         *
  * the dyn SQL query in this scenario.                          *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply corrective PTF when available                          *
  ****************************************************************
  Db2 12 for z/OS user requested Accelerator modeling using Db2
  subsystem parameter (zparm) ACCELMODEL = YES and
  QUERY ACCELERATION ^= NONE , and EXPLAIN is used to generate
  a row in Db2 EXPLAIN table DSN_QUERYINFO_TABLE for a dynamic
  query where column QINAME1 = 'ACCELMDL'. However, Db2 does not
  insert the expected row in DSN_QUERYINFO_TABLE for the dyn SQL
  query.
  .
  Further investigation showed that this problem occurred when
  no Accelerator was active or STARTed in Db2z at that time.
  .
  A DSN_QUERYINFO_TABLE row where column QINAME1='ACCELMDL' is
  expected for the dyn SQL query in this scenario when Db2 zparm
  ACCELMODEL=YES to requesting Accelerator modeling.
  .
  In addition, in the EXPLAIN table PLAN_TABLE row for the dyn
  query, the column ACCESSTYPE = 'A' and column QBLOCK_TYPE =
  'SELECT' are expected, to reflect the successful "accelerator
  modeling" for this query scenario; instead of the ACCESSTYPE
  and QBLOCK_TYPE values indicating the regular Db2z-specific
  values.
  .
  The problem does not occur if an Accelerator is STARTed in Db2z
  at the time, or when QUERY ACCELERATION = NONE.
  

Problem conclusion

• Db2 12 for z/OS code was corrected to insert the expected
  QINAME1 = 'ACCELMDL' row into EXPLAIN table DSN_QUERYINFO_TABLE
  for the dynamic query in this reported scenario when
  no Accelerator is STARTed in Db2z.
  .
  Also, with this change, in the EXPLAIN table PLAN_TABLE row
  for the dynamic query, the column ACCESSTYPE = 'A' and column
  QBLOCK_TYPE = 'SELECT' to reflect the successful "accelerator
  modeling" for this query scenario.
  .
  Additional search keywords: SQLEXPLAIN
                              IDAAV5R1/K IDAAV7R1/K IDAAV7R5/K
  

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:

  UI75314

Modules/Macros

• DSNXOMPS
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RC10 PSY UI75314

     UP21/05/18 P F105

Fix is available

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