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IT31808: TRAP MAY HAPPEN WHEN RUNNING DB2EXPLN BY '-CACHE' OPTION WITH WRONG ENVIRONMENT ID

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APAR status

  • Closed as fixed if next.

Error description

  • TRAP may happen when running db2expln by '-cache' option with
    wrong environment ID.
    The stack pattern is like below.
    
    ..
    sqloEDUCodeTrapHandler
    _Z18sqlra_hash_loc_envP8sqlrr_cbP14sqlra_cmpl_envP17sqlra_cached
    _stmtibPP16sqlra_cached_envS7_PiPm
    _Z18sqlra_find_var_envP8sqlrr_cbP17sqlra_anchor_stmtP17sqlra_cac
    hed_stmtP13sqlra_stmt_idjP14sqlra_cmpl_env15sqlra_fill_modebbPiS
    A_PP16sqlra_cached_envSA_Pm
    _Z14sqlra_find_varP8sqlrr_cbP17sqlra_cached_stmt13sqlra_stmt_idj
    jPhjthP14sqlra_cmpl_env15sqlra_fill_modePiiS8_iiiS8_P14SQLP_LOCK
    _INFOPP16sqlra_cached_varS8_bSA_Pb
    sqlra_get_sql_cache_sect
    _Z29sqlerTrustedRtnCallbackRouterjPPv
    sqlCache
    ..
    
    The example reproduction scenario is like below.
    
    - connect to a db
    - issue a dynamic SQL statement
    - issue db2pd -db <dbname> dynamic and in the Dynamic SQL
    Variations find the AnchID/StmtID/EnvID/VarID of a variation in
    the cache.
    
    For example, from this part of the output:
    
    Dynamic SQL Variations:
    Address            AnchID StmtUID    EnvID      VarID
    NumRef     Typ Lockname                   Val Insert Time
    Sect Size  Num Copies
    0x00007FFEFA17C0A0 68     1          1          1          1
    1   010000000100000001008008D6 Y   2020-02-04-10.09.29.589167
    1928       0
    
    There is an entry in the cache with a AnchID/StmtID/EnvID/VarID
    of 68,1,1,1.
    
    Running the following command, db2explan generates the section
    from the cache explained.
    
    db2expln -d <dbname> -cache 68,1,1,1 -o expln.out
    
    Specifying an ID that is not in the cache should result in a
    "Section not found in SQL cache" message in the expln.out file.
    This will happen, for example if the following is specified:
    
    db2expln -d <dbname> -cache 68,20,1,1 -o expln.out
    
    However if one specifies a correct anchor ID and statement ID,
    but the environment ID is not in the cache, the trag may occur.
    
    db2expln -d <dbname> -cache 68,1,33,1 -o expln.out
    

Local fix

  • Running 'db2expln' with correct environment ID.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All platform                                                 *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to V11.1 mod4 fixpack 6                              *
    ****************************************************************
    

Problem conclusion

Temporary fix

Comments

APAR Information

  • APAR number

    IT31808

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED FIN

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2020-02-10

  • Closed date

    2021-03-16

  • Last modified date

    2021-03-16

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

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

Fix information

Applicable component levels

[{"Line of Business":{"code":"LOB10","label":"Data and AI"},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSEPGG","label":"Db2 for Linux, UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1"}]

Document Information

Modified date:
18 March 2021