IT24493: LOCK EXCLUSIVE MDC TABLE WITH LOCKSIZE SET TO BLOCKINSERT, INSERTING ROWS WILL RESULT IN ADDITIONAL LOCKS BEING ACQUIRED.

APAR status

• Closed as program error.

Error description

• Lock exclusive MDC table with LockSize set to BlockInsert, then
  inserting Rows with the same dimension value consecutively will
  result in additional rows locks being acquired on this MDC
  Table.
  
  The folllowing is a simple reproduction of this issue:
  
  ----- Begin repro.ksh -----
  #!/bin/ksh
  
  export DB2OPTIONS="-ctv"
  dbName="wsdb"
  
  db2 "create db $dbName"
  db2 "connect to $dbName"
  db2 "create tablespace ts1"
  db2 "create table t1 (i1 int) organize by (i1) in ts1"
  db2 "alter table t1 locksize blockinsert"
  db2 +c "lock table t1 in exclusive mode"
  db2 +c "insert into t1 values
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0"
  db2pd -db $dbName -locks
  echo
  db2 "commit"
  db2 "drop tablespace ts1"
  db2 "terminate"
  ----- End of repro.ksh -----
  

Local fix

• A workaround to this problem is to set LockSize to either Table
  or Row before the INSERT command and set it back afterwards.
  
  I.e.
  db2 +c "lock table t1 in exclusive mode"
  db2 +c "alter table t1 locksize table"
  db2 +c "insert into t1 values
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0"
  db2 +c "alter table t1 locksize blockinsert"
  db2pd -db $dbName -locks
  echo
  db2 "commit"
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * ALL                                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to Db2 11.1 Mod 4 Fixpack 4 or higher                *
  ****************************************************************
  

Problem conclusion

• First fixed in Db2 11.1 Mod 4 Fixpack 4
  

Temporary fix

Comments

APAR Information

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

  IT24456

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

Fix information

• Fixed component name

  DB2 FOR LUW

• Fixed component ID

  DB2FORLUW

Applicable component levels

• RB10 PSN

     UP