A fix is available
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 number
PH16694
Reported component name
DB2 OS/390 & Z/
Reported component ID
5740XYR00
Reported release
C10
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2019-09-10
Closed date
2021-05-10
Last modified date
2021-06-02
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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Document Information
Modified date:
03 June 2021