DB2 FOR LUW / DB2FORLUW / 970 - DB2

DB2 Rewrite will optimize the performance of union all views by 
performing pushdown of local predicates of a base table which 
joins the union all view if the join is considered to be non 
expanding. 
 
For the rewrite to take place, all the following conditions must 
be true: 
 
1. If we have join predicates from base table that cover all the 
columns in a unique index of Base Table, and, 
2. those columns, via equality classes in various levels, can be 
mapped to all the branches of the UA that also ranges over the 
same base table (BT) 
3. There must be no recursion or correlation in the joins 
related to the rewrite. 
4. The union all must not have a Update, Delete, Insert 
consumer, fetch n rows or be part of a subquery. 
5. The joins with the base table must not be correlated 
6. There must be no side-effects, external action or scratchpad 
below the UNION ALL 
 
Result: 
Local predicates on base table are pushed down to all the base 
tables under Union All view.

**************************************************************** 
* USERS AFFECTED:                                              * 
* All                                                          * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* DB2 Rewrite will optimize the performance of union all views * 
* by                                                           * 
* performing pushdown of local predicates of a base table      * 
* which                                                        * 
* joins the union all view if the join is considered to be non * 
*                                                              * 
* expanding.                                                   * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to DB2 v970 fixpack 4                                * 
****************************************************************

DB2 Version 9.7 Fix Pack 4 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 5 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 6 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 7 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 8 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 9 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 9a for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 10 for Linux, UNIX, and Windows
 

The enhancement is available in DB2 v970 fixpack 4

keiner bekannt / siehe Local-Fix

Datum - Problem gemeldet    :
Datum - Problem geschlossen :
Datum - der letzten Änderung:

13.05.2010
29.04.2011
29.04.2011

9.7.0