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LI73318: DATA CORRUPTION WHEN A LOB OBJECT ASSOCIATED WITH A TABLE GROWS LARGER THAN 2 TB

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • When a large object (BLOB, CLOB, or DBCLOB data type) object
    that is associated with a table crosses the 2 terabyte (TB) size
    boundary, there is a problem in the space allocation algorithm
    that can lead to corruption of the table space.  For example a
    previously allocated extent might be erroneously reused.  One
    occurrence of this problem resulted in the beginning pages of
    the LOB table space being overwritten when the LOB object grew
    larger than 2 terabytes.
    

Local fix

  • Use a range partitioned table to split LOBs for a column into
    separate LOB objects to avoid crossing the 2TB threshold for a
    single LOB object.
    
    The size of the LOB object can be determined using the following
    command:
    
    db2pd -db dbname -tcbstats
    
    One of the columns that is generated in this report is LobSize
    (which is shown as number of pages).  A quick calculation
    (number of pages * page size) will give the size of the LOB
    object.
    
    If the LOB object has already crossed the 2TB boundary just
    applying the fix will not correct the issue, the table will
    still need to be rebuilt.
    

Problem summary

  • Problem Description: a LOB object that grows larger than 2TB can
    become corrupt
    Problem Summary: see above
    Users Affected: Any with large LOB objects associated with a
    table.
    

Problem conclusion

  • Problem was first fixed in Version 9.5 FixPak 2
    

Temporary fix

  • n/a
    

Comments

APAR Information

  • APAR number

    LI73318

  • Reported component name

    DB2 UDB WSE LIN

  • Reported component ID

    5765F3504

  • Reported release

    950

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2008-03-28

  • Closed date

    2008-09-03

  • Last modified date

    2008-09-04

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

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

    LI73319

Fix information

  • Fixed component name

    DB2 UDB WSE LIN

  • Fixed component ID

    5765F3504

Applicable component levels

  • R810 PSN

       UP

  • R820 PSN

       UP

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Document Information

Modified date:
04 September 2008