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DB2 - Problembeschreibung

Problem IC61784 Status: Geschlossen

OPTIMIZER MIGHT OVERESTIMATE THE SELECTIVITY OF A RANGE PREDICATE
WHICH XML INDEX IS CREATED AS TIMESTAMP DATA TYPE

Produkt:
DB2 FOR LUW / DB2FORLUW / 970 - DB2
Problembeschreibung:
Problem Description: Optimizer might overestimate the 
selectivity of a range predicate when the range predicate is 
based on an XML index defined as TIMESTAMP data type. Optimizer 
might choose this TIMESTAMP data type XML index and it could 
lead to inefficient plan. 
 
For example, the following query has range predicate on the 
TIMESTAMP data type XML index issueIndex.  Optimizer might 
overestimate selectivity of the range predicate. 
 
create table T(id int, xmldata XML); 
create index issueIndex on T(xmldata) 
  generate key using xmlpattern '/test/account/issueDate' as 
SQLTIMESTAMP; 
 
   SELECT X.col 
   from T, 
 xmltable(' 
     for $i in 
 
$doc/test/account[issueDate[.<=xs:dateTime("2008-12-31T00:00:00 
") 
 and .>=xs:dateTime("2008-01-01T00:00:00")]] 
   return $i' 
   passing T."XMLDATA" as "doc" 
   columns col TimeStamp path 'issueDate') X; 
 
 Local fix: No. Recommendation: upgrade to v95fp5 or v97fp1
Problem-Zusammenfassung:
**************************************************************** 
* USERS AFFECTED:                                              * 
* Users who issue XQuery or SQL/XML query containing the range * 
* predicate based on an XML index defined as TIMESTAMP data    * 
* type.                                                        * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* Optimizer might overestimate the selectivity of a range      * 
* predicate when the range predicate is  based on an XML index * 
* defined as TIMESTAMP data type. Optimizer might choose this  * 
* TIMESTAMP data type XML index and it could lead to           * 
* inefficient plan.                                            * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to V97FP1.                                           * 
****************************************************************
Local-Fix:
Recommendation: upgrade to v95fp5 or v97fp1
verfügbare FixPacks:
DB2 Version 9.7 Fix Pack 1 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 2 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 3 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 3a for Linux, UNIX, and Windows
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 7 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 9a for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 6 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 10 for Linux, UNIX, and Windows

Lösung
The XML index defined as TIMESTAMP data type will be evaluated 
as access plan candidate.
Workaround
keiner bekannt / siehe Local-Fix
Weitere Daten
Datum - Problem gemeldet    :
Datum - Problem geschlossen :
Datum - der letzten Änderung:
29.06.2009
25.01.2010
25.01.2010
Problem behoben ab folgender Versionen (IBM BugInfos)
9.7.FP1
Problem behoben lt. FixList in der Version
9.7.0.1 FixList