In DB2 for Linux, Unix and Windows, Fixpack 7 or Fixpack 8, the
optimizer might choose a Merge Join (MSJOIN) in cases where the
column(s) in a join predicate also have inequality predicates
applied, those predicates limit the range of the column's
values, and one or both of the columns are the lead column in an
index. For example:
- table t1, with an integer column, c1, with a range of 1 - 100.
- table t2, with an integer column, c2, with a range of 1 - 100.
- inequality predicates: t1.c1 >= 10 and t1.c1 <= 90
- join predicate between t1 and t2: t1.c1 = t2.c1
If the above conditions exist, and the optimizer picked a Hash
Join or Nest Loop Join plan in a fixpack level prior to DB2 for
Linux, Unix and Windows, Version 9.5 Fixpack 7, then you are
likely encountering this APAR. |
****************************************************************
* USERS AFFECTED: *
* All DB2 LUW users *
****************************************************************
* PROBLEM DESCRIPTION: *
* In DB2 for Linux, Unix and Windows, Fixpack 7 or Fixpack 8, *
* the optimizer may choose a Merge Join (MSJOIN) in cases *
* where the column(s) in a join predicate also have inequality *
* predicates applied, those predicates limit the range of the *
* column's values, and one or both of the columns are the lead *
* column in an index. For example: *
* - table t1, with an integer column, c1, with a range of 1 - *
* 100. *
* - table t2, with an integer column, c2, with a range of 1 - *
* 100. *
* - local range predicate: t1.c1 between 10 and 90 *
* - join predicate between t1 and t2: t1.c1 = t2.c1 *
* *
* If the above conditions exist, and the optimizer picked a *
* Hash Join or Nest Loop Join plan in a fixpack level prior to *
* DB2 for Linux, Unix and Windows, Version 9.5 Fixpack 7, then *
* you are likely encountering this APAR. *
* Note: problem does not occur in DB2 for Linux, Unix and *
* Windows Version 9.7 or later versions or fixpacks. *
****************************************************************
* RECOMMENDATION: *
* Upgrade the DB2 for Linux, Unix and Windows server to *
* Version 9.5 fixpack 10 or later *
**************************************************************** |
