PM80445: "READ_UNCOMMITTED" SETTING FOR THE FETCH PLAN ISOLATION LEVEL IS IGNORED IN DB2DICTIONARY

8.5.0.2: WebSphere Application Server V8.5 Fix Pack 2

APAR status

• Closed as program error.

Error description

• When a user sets an isolation query hint of "READ_UNCOMMITTED"
  for DB2, this hint/isolation level is ignored and the default
  isolation level is used.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM WebSphere Application      *
  *                  Server                                      *
  *                  Liberty Profile                             *
  ****************************************************************
  * PROBLEM DESCRIPTION: "READ_UNCOMMITTED" isolation level      *
  *                      setting for the OpenJPA fetch plan      *
  *                      isolation level is ignored in           *
  *                      DB2Dictionary.                          *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Take the following JPA Query hint:
  Query query = EntityManager.createQuery(.....
  query.setHint("openjpa.FetchPlan.Isolation",
  "READ_UNCOMMITTED");
  When you set a query hint as shown above for DB2, no "with UR"
  clause is append to the query; the setting is completely
  ignored.
  

Problem conclusion

• With this fix, code has been added to OpenJPA to support a
  "READ_UNCOMMITTED" isolation level setting for the OpenJPA
  fetch plan. It should be noted that an uncommitted read is
  risky and should be avoided if possible. The JPA specification
  requires a minimum of read committed isolation to ensure that
  no "dirty reads" or "non-repeatible reads" can occur.  Use of
  "READ_UNCOMMITTED" isolation may cause data integrity
  problems.
  
  The fix for this APAR is currently targeted for inclusion in
  fix pack 8.5.0.2. Please refer to the Recommended Updates page
  for delivery information:
  http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
  

Temporary fix

Comments

APAR Information

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

  PM71710

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

Fix information

• Fixed component name

  LIBERTY PROFILE

• Fixed component ID

  5724J0814

Applicable component levels

• R850 PSY

     UP