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IZ05975: PAGE AND OBJECT DO NOT MATCH - DATABASE CRASH WITH SQLBUFIX PROBE 155 DURING QUERY EXECUTION

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • On a system with INTRA_PARALLEL enabled, the execution of a
    query that requires a sort (for example, due to a SELECT
    DISTINCT, ORDER BY, or aggregation operator) may cause the
    database to abend.  A message similar to the following will be
    seen in the db2diag.log
    .
    2007-09-08-08.43.55.642903-240 I23338A2173        LEVEL: Severe
    PID     : 11111                TID  : 1           PROC :
    db2agntp (xxxxxxx) 0
    INSTANCE: xxxxxxxx             NODE : 000
    APPHDL  : 0-484                APPID:
    112.32.74.52.39558.070905064434
    AUTHID  : XXXXXXX
    FUNCTION: DB2 UDB, buffer pool services, sqlbufix, probe:155
    DATA #1 : String, 40 bytes
    sqlbufix : Page and Object do not Match!
    .
    The mismatch is between the page header information, which will
    appear in the diag log similar to this:
    .
    DATA #2 : Page header, PD_TYPE_SQLB_PAGE_HEAD, 48 bytes
    pageHead: {pool:4;obj:11;type:128} PPNum:1 OPNum:1
    .
    and the buffer page descriptor, which will appear in the diag
    log similar to this:
    .
    DATA #3 : Buffer page descriptor, PD_TYPE_SQLB_BPD, 152 bytes
      Pagekey: {pool:4;obj:0;type:128} PPNum:1
    .
    The most important pieces of information are that the page type
    is a temporary page (type is 128) and that the object ID is set
    to 0 in the BPD.
    .
    The stack will show function sqlbufix and lower in the stack
    you will see sort functions such as sqlsmergerec.
    

Local fix

  • The problem can be worked around by disabling INTRA_PARALLEL.
    

Problem summary

  • Users affected:  all users of INTRA_PARALLEL
    Problem description:  During execution of a query that uses a
    sort, the database may crash and the db2diag.log will show an
    error from sqlbufix probe 155.
    Problem summary:  With INTRA_PARALLEL enabled, it is possible
    that a temporary page may be freed twice by different subagents,
    resulting in the crash.  This APAR fixes the problem by
    serializing access to the temp page.
    PROBLEM CONCLUSION: First fixed in DB2 UDB Version 9, Fix Pack
    5
    

Problem conclusion

  • First fixed in DB2 UDB Version 9, Fix Pack 5
    

Temporary fix

  • Disable INTRA_PARALLEL.
    

Comments

APAR Information

  • APAR number

    IZ05975

  • Reported component name

    DB2 UDB ESE SOL

  • Reported component ID

    5765F4102

  • Reported release

    910

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2007-10-04

  • Closed date

    2008-05-07

  • Last modified date

    2008-07-10

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

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

    IZ05977 IZ18557

Fix information

  • Fixed component name

    DB2 UDB ESE SOL

  • Fixed component ID

    5765F4102

Applicable component levels

  • R910 PSN

       UP

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Document Information

Modified date:
10 July 2008