PH59459: THE VISUAL EXPLAIN BUTTON IN DATA STUDIO DOESN'T SHOW THE EXPLAIN GRAPH OF AN ACCELERATED QUERY

APAR status

• Closed as documentation error.

Error description

• The Visual Explain button in Data Studio (located in the Data
  Studio SQL Editor) doesn't show the explain graph of an
  accelerated query any more. Accelerated query in this case means
  
  - you have set the QUERY_ACCELERATION option in the Visual
  Explain dialogue to either ELIGIBLE, ENABLE, or ALL
  - Db2 for z/OS has considered the query to be elibible for the
  Accelerator.
  
  Instead of showing the Explain graph obtained from
  the Accelerator, one of the following symptons can occur:
  - An error message occurs after several minutes:
  Ýjcc¨Ýt4¨Ý2050¨Ý11326¨Ý4.31.10¨ Execution failed due to a
  distribution protocol error that caused deallocation of the
  conversation. The identified cursor is not open.
  ERRORCODE=-4499, SQLSTATE=58009
  - A small graph is shown after several minutes showing that the
  query can be accelerated but the explain graph is missing.
  
  The issue occurs when using the stored procedures for
  Accelerator maintenance level 7.5.9 or later.
  
  It is caused by a change of stored procedure
  SYSPROC.ACCEL_GET_QUERY_EXPLAIN introduced with
  
  maintenance level 7.5.9.
  
  A fix for this issue will be made available with Accelerator
  maintenance level 7.5.13.
  
  Additional keywords:
  TS014317842 TS005409738
  Visual Explain #idaa759 Data Studio
  SYSPROC.ACCEL_GET_QUERY_EXPLAIN
  ERRORCODE4499, SQLSTATE58009
  GH/.../Customer-Cases/issues/614
  DT258707
  

Local fix

• The following workaround exists to get the explain graph for an
  accelerated query:
  - Route the query to the accelerator by using acceleration
  option SET CURRENT QUERY ACCELERATION ALL.
  - Cancel the query immediately after it has arrived on the
  accelerator to avoid complete execution.
  - Identify the query in the Accelerator Studio Query Monitoring
  section.
  - Use the Show Plan option to show the Explain graph for this
  query.
  

Problem summary

• Problem Summary:
  The Visual Explain button in Data Studio doesn't show the
  explain graph of an accelerated query.
  
  
  
  Users Affected:
  Users of Db2 Analytics Accelerator Studio using the
  
  - Stored Procedures for Accelerator maintenance level 7.5.9
  (7.5.10.x, 7.5.11.x, 7.5.12.x)
  and the
  
  - Visual Explain button to see the Explain graph of an
  accelerated query.
  
  
  
  Problem Scenario:
  See APAR Error description.
  
  Problem Symptoms:
  See APAR Error description.
  

Problem conclusion

• The issue has been fixed with PTF UI97750 for APAR PH61845
  delivering a new edition of the Stored Procedures for
  Db2 Analytics Accelerator V7.5 for z/OS.
  
  a) The stored procedure ACCEL_GET_QUERY_EXPLAIN has been
  reverted back to its original purpose to only retrieve Db2
  EXPLAIN information for a query from an accelerator. It does
  
  no longer return the output of the db2support command from
  
  the accelerator.
  
  b) A new stored procedure ACCEL_GET_QUERY_DOC has been
  
  introduced that returns the output of the db2support
  
  command from the accelerator.
  
  Upgrade your Stored Procedures by applying PTF UI97750
  
  or its successor.
  

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:

Fix information

Applicable component levels