DB2 FOR LUW / DB2FORLUW / A50 - DB2

Negative COLCARD value can cause OPTIMIZER to choose a bad plan 
resulting in poor query performance. This issue can occur if all 
of the following conditions are present: 
 
1. If COLCARD exceeds 2147483647. 
 
2. Almost all possible values between high2key and low2key 
appear in the table. 
 
3. The column is BIGINT type. 
 
4. The column is not the leading column of any index. 
 
5. The column is not unique.

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* USERS AFFECTED:                                              * 
* All                                                          * 
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* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
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* RECOMMENDATION:                                              * 
* Upgrade to DB2 v10.5 FP5 or higher                           * 
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Workaround for this issue is to manually update COLCARD in 
SYSSTAT.COLUMNS table. You can do this as follows: 
 
1. db2  "select count(distinct(<columnname>)) from 
<schema>.<tablename>" 
 
where: 
<columnname> is the name of the column with the negative COLCARD 
value. 
<schema> is the schema for the table. 
<tablename> is the name of the table. 
 
2. Update the value as follows: 
 
db2 "UPDATE SYSSTAT.COLUMNS SET COLCARD=<value> WHERE COLNAME = 
'<coulmnname>' AND TABNAME = '<tablename>' AND TABSCHEMA = 
'<schema>' " 
 
where: 
<value> is the result of the query from step 1.

Fixed in DB2 v10.5 FP5

not known / see Local fix

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

14.08.2014
27.01.2015
27.01.2015