|
Problem IC85425
|
Status: Closed |
QUERY WITH A UNION AND TWO CORRELATED BRANCHES MIGHT RETURN INCORRECT RESULTS IN PARTITIONED DATABASE ENVIRONMENTS |
| product: |
DB2 FOR LUW / DB2FORLUW / A10 - DB2 |
| Problem description: |
If you are using the partitioned database environment and
your query satisfies the following conditions, then the results
returned might be incorrect
1. there is a table, T1, that is hash distributed across two or
more database partitions;
2. T1 is correlated to multiple branches below a UNION;
3. each branch of the UNION is correlated to at least one
different column in T1;
4. one of the branches is correlated to the hash distribution
key of T1;
5. the columns in the select list of each UNION branch includes
the correlation column.
The following is an example of a query that satisfies the above
conditions, where T1 is hash distributed on column X:
SELECT *
FROM T1,
TABLE(SELECT X FROM T2 WHERE X = T1.X
UNION ALL
SELECT Y FROM T3 WHERE Y = T1.Y); |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All users of database partitioning feature. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 version 10.1.0.2. *
**************************************************************** |
| Local Fix: |
You can avoid the problem by rewriting the query to remove the
correlation below the UNION. |
| available fix packs: |
DB2 Version 10.1 Fix Pack 2 for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 3 for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 4 for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 3a for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 6 for Linux, UNIX, and Windows
|
| Solution |
The problem is first fixed in DB2 version 10.1.0.2. |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 19.07.2012
07.12.2012
07.12.2012 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 10.1.0.2
|
 |
| 10.5.0.2
|
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