PM69866: NO RECORD FOUND (SQLCODE +100) WHEN A ISO(UR) ACCESS IS READING A LOB COLUMN

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• DB2 development has found a timing window in the code that
  incorrectly returns a no record found NRF SQLCODE100 when a
  ISO(UR) access is reading a lob column.
  Code added in V9 remove reading the pseudo deleted Aux Index
  key/rid which is allowing the access to the lob column
  during an SQL update of the lob column to incorrect sqlcode +100
  

Local fix

• n/a
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All DB2 9 and DB2 10 for z/OS users of LOBs  *
  *                 (large objects) with isolation level UR      *
  *                 (Uncommitted Read).                          *
  ****************************************************************
  * PROBLEM DESCRIPTION: An unexpected SQLCODE100 (SQLCODE +100) *
  *                      or no records found is returned for an  *
  *                      ISO(UR) reader when fetching LOB        *
  *                      columns.                                *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  An unexpected SQLCODE100 (SQLCODE +100) or no records found can
  be returned for an ISO(UR) reader when fetching LOB columns.
  
  Apar PM18903 (v9 ptf UK60323) intended to close a small
  serialization window to avoid LOB corruption in a data sharing
  environment when a LOB updater and a LOB UR reader are accessing
  the same LOBs.  At the time, it was thought that the fix
  provided in PM18903 (which was not to read a pseudo deleted LOB)
  might close the serialization window.  Unfortunately, it was
  later discovered that this was not the case for v9.  As a
  result, an SQLCODE +100 could be returned as now reported.
  
  In summary, PM18903 did not correct the inconsistency involving
  the read LRSN problem but did restore code that always requests
  a pseudo delete.
  
  The following paragraph provides additional information about
  the serialization which could lead to this LOB inconsistency.
  
  Today, when a LOB is deleted, DB2 always does a pseudo delete on
  both the LOB data storage and its associated Aux index.  DB2
  deploys a read LRSN to claim the LOB data storage and its Aux
  index entry when there is no active thread to access the data.
  In the past, due to an inconsistent read LRSN value, DB2 could
  mistakenly lose both the LOB data storage and its Aux index when
  there is still an active thread accessing the data.
  

Problem conclusion

• The code in DB2 is modified to prevent the SQLCODE +100 or no
  records found condition for ISO(UR) readers of LOB columns.
  
  Additional Keywords: SQLCODE100 SQLLOB INCORROUT
                       SQLINCORR SQLINCORROUT DB2INCORR/K
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  UK81415 UK81416

Modules/Macros

• DSNODCRL
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UK81415

     UP12/09/14 P F209

• R910 PSY UK81416

     UP12/09/14 P F209

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.