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IT32238: IN VERY RARE SCENARIOS CONCURRENT UPDATES OR INSERTS INTO INSERTTIME CLUSTERING (ITC) TABLES CAN LEAD TO DEADLATCH

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APAR status

  • Closed as fixed if next.

Error description

  • The deadlatch is between a page latch
    (SQLO_LT_SQLB_BPD__bpdLatch_SX) and the DMS Page Cache Latch
    (SQLO_LT_SQLD_PAGE_CACHE__pageCacheLatch)
    
    The deadlatch is encountered during two or more concurrent
    update and/or insert statements on an ITC table. ITC tables are
    the only tables that are affected. Furthermore, for an ITC table
    to be susceptible it requires very specific conditions related
    to blocks being in the possibly-empty state while the concurrent
    transaction utilizes that block.
    
    The stack of one of the deadlatched threads will look like the
    following.  sqldbFindAppendOrEmptyBlock will be involved:
    
    SQLO_SLATCH_CAS64::getConflictComplex(const unsigned long)
    SQLO_SLATCH_CAS64::getConflict(const unsigned long)
    IPRA.$sqlbFindPageInBPOrSim(SQLB_FIX_CB*,int,unsigned
    long,SQLB_BufferPool*)
    sqlbfix(SQLB_FIX_CB*)
    sqldbFindAppendOrEmptyBlock(sqeAgent*,SQLD_DFM_WORK*,SQLD_TABLE_
    CACHE*,SQLD_TABLE_CACHE*,unsigned long*,SQLZ_RID*)
    IPRA.$sqldCreateAppendCachePagesForMDCTable(SQLD_DFM_WORK*,SQLD_
    PAGE_CACHE*,SQLB_FIX_CB*,long,unsigned
    int*,SQLD_TABLE_CACHE*,SQLD_TABLE_CACHE*,dmsBatchCreateCB*)
    sqldCreateNewAppendCache(SQLD_DFM_WORK*,SQLD_PAGE_CACHE*,unsigne
    d long,unsigned long,unsigned
    long*,SQLD_TABLE_CACHE*,SQLD_TABLE_CACHE*)
    sqldExtendAppendCache(SQLD_DFM_WORK*,unsigned
    long,SQLD_TABLE_CACHE*,SQLD_TABLE_CACHE*)
    sqldSearchPageCache(SQLD_DFM_WORK*,SQLD_PAGE_CACHE*,SQLD_TABLE_C
    ACHE*,SQLD_TABLE_CACHE*)
    sqldb_insertITCRow(SQLD_DFM_WORK*,SQLD_TABLE_CACHE*,SQLD_TABLE_C
    ACHE*)
    sqldMDCInsertRow(SQLD_DFM_WORK*,SQLD_PAGESLOT*,SQLD_PAGESLOT*,SQ
    LP_LOCK_INFO*)
    IPRA.$sqldCreateOverflow(SQLD_DFM_WORK*,SQLD_PAGESLOT,SQLD_PAGES
    LOT,SQLD_PAGESLOT,unsigned long,unsigned long,unsigned long)
    IPRA.$sqldUpdateRowComplex(SQLD_DFM_WORK*,SQLD_XOR_UPDATE*,unsig
    ned char*,int)
    sqldUpdateRow(SQLD_DFM_WORK*,SQLD_XOR_UPDATE*,unsigned
    char*,int)
    sqldRowUpdate(sqeAgent*,SQLD_CCB*,unsigned
    long,SQLD_VALUE**,unsigned long,void**)
    sqlriupd(sqlrr_cb*)
    sqlriSectInvoke(sqlrr_cb*,sqlri_opparm*)
    sqlrr_process_execute_request(sqlrr_cb*,int,bool)
    sqlrr_execute(db2UCinterface*,UCstpInfo*)
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * Users of INSERT TIME CLUSTERING (ITC) TABLES                 *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to 11.1.4.6 (mod 4 fix pack 6)                       *
    ****************************************************************
    

Problem conclusion

Temporary fix

Comments

APAR Information

  • APAR number

    IT32238

  • 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

    2020-03-19

  • Closed date

    2021-03-19

  • Last modified date

    2021-03-19

  • 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:
20 March 2021