IT03863: ASSERTION FAILURE SEGV IN LKDEQUE WHEN USING PDQ, COMMITTED READ LAST COMMITTED ISOLATION AND BATCHEDREAD_INDEX SET TO 0

APAR status

• Closed as program error.

Error description

• A query that has PDQ enabled and multiple threads, that is using
  the committed read last committed isolation level and it
  encounters a locked row doing a index scan when
  BATCHEDREAD_INDEX is set to 0 will assert fail crash the server
  with the following stack trace:
  
  afstack
  mt_ex_throw_sig
  afsig_handler
  <signal frame>
  lkdeque
  lkwait
  lkmanagex
  lkrow
  read_record_lc
  read_record
  gather_records
  rsread
  fmread
  gettupl
  scan_next
  join_next
  producer_thread
  startup
  
  
  Portions of onstat -g ses output that show pdq enabled and
  committed read last committed isolation level:
  
  tid      name     rstcb            flags    curstk   status
  242      sqlexec  66608740         ---P---  6784     sleeping
  secs: 1     -
  246      nljoin_1 66608ff8         ----R--  1717808992 running-
  247      nljoin_1 666098b0         Y------  496      cond wait
  await_MC1 -
  248      nljoin_1 6660a168         L---R--  1719364656 running-
  249      nljoin_1 6660aa20         Y------  496      cond wait
  await_MC1 -
  250      scan_2.0 6660b2d8         Y------  496      cond wait
  await_MC2 -
  251      scan_2.1 6660bb90         Y------  496      cond wait
  await_MC2 -
  
  
  sqscb info
  scb              sqscb            optofc   pdqpriority
  optcompind  directives
  670621c0         681a8028         0        40          2
  1
  
  Sess       SQL            Current            Iso Lock       SQL
  ISAM F.E.
  Id         Stmt type      Database           Lvl Mode       ERR
  ERR  Vers  Explain
  183        SELECT         clear              LC  Not Wait   0
  0    9.24  Off
  
  Lastly the value of BATCHEDREAD_INDEX from the onstat -c output:
  
  BATCHEDREAD_INDEX   0
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * 12.10 users using Last Committed and PDQ                     *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Update to IDS-12.10.xC5                                      *
  ****************************************************************
  

Problem conclusion

• Problem Fixed In IDS-12.10.xC5
  

Temporary fix

Comments

APAR Information

• 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

  INFORMIX SERVER

• Fixed component ID

  5725A3900

Applicable component levels

• RA10 PSN

     UP

• RA10 PSY

     UP

• RB10 PSN

     UP

• RB10 PSY

     UP

• RB50 PSN

     UP

• RB50 PSY

     UP

• RB70 PSN

     UP

• RB70 PSY

     UP

• RC10 PSN

     UP

• RC10 PSY

     UP