IBM Support

IT30242: SQLIUNDOADDKEY MAY CRASH THE DATABASE IF ANOTHER TRANSACTION IS PERFORMING A SMO ON THE SAME PAGE

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APAR status

  • Closed as program error.

Error description

  • Database System crash causes the production database damaged.
    User can not make new connection on database.
    
    Multiple FODC observed before DATABASE CRASH
    
    Db2diag.log error messages:
    2019-08-13-13.16.13.506658+000 I28539404E630         LEVEL:
    Severe
    PID     : 4079                 TID : 139808458401536 PROC :
    db2sysc 0
    INSTANCE: db2edwp1             NODE : 000            DB   :
    DBEDWP1
    APPHDL  : 0-16862              APPID:
    10.5.38.27.47106.190813131543
    UOWID   : 1                    ACTID: 111068
    AUTHID  : EDAVDM1P             HOSTNAME: sl55edwdbp01
    EDUID   : 231370               EDUNAME: db2agent (DBEDWP1) 0
    FUNCTION: DB2 UDB, index manager, sqliUndoAddKey, probe:519
    RETCODE : ZRC=0x8510000A=-2062548982=SQLP_LFUL
              "Lock list full - SQL0912 Reason code 1"
              DIA8310C Lock list was full.
    
    Root Cause:
    
    When undoing a change of a page which another transaction is
    currently performing a structure modification operation (SMO)
    such as a page split on, the undo process will see the SMO bit
    and try to grab the tree lock again, which might hit the lock
    manager boundary and crash the database.
    
    The issue happened during undo, typically during undo we do not
    acquire any additional resources, ie. we should have acquired
    whatever lock during statement execution, not during undo .. or
    at least reserved the LRB via IN mode.
    
    But for index undo a special case could happen if another
    transaction is doing a structure modification operation(SMO) and
    holding a tree lock, the undo process would wait for that SMO
    finished by acquiring the tree lock to see if has been released
    by the SMO, which might hit the lock manager boundary and crash
    the database.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Db2 11.1 Mod 4 Fixpack 5 or higher                *
    ****************************************************************
    

Problem conclusion

  • First fixed in Db2 11.1 Mod 4 Fixpack 5
    

Temporary fix

  • See local fix or increase lock size list
    

Comments

APAR Information

  • APAR number

    IT30242

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2019-09-10

  • Closed date

    2020-01-16

  • Last modified date

    2020-01-16

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

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

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • RB10 PSN

       UP

[{"Business Unit":{"code":"BU048","label":"IBM Software"},"Product":{"code":"SSEPGG","label":"DB2 for Linux, UNIX and Windows"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1","Edition":"","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Document Information

Modified date:
16 January 2020