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Problem IT35118
|
Status: Closed |
POSSIBLE WRONG RESULT WITH ALWAYS-FALSE PRED OR EXISTS PRED
|
| product: |
DB2 FOR LUW / DB2FORLUW / B10 - DB2 |
| Problem description: |
When a query has always-false predicates or EXISTS predicates,
we may get wrong results. More specifically, we may get more
rows returned than anticipated.
Another example with always-false predicates:
create table t1 (c1 int);
create table t2 (c1 int);
insert into t1 values (5);
insert into t2 values (5), (5);
-- Bad query with "always false" predicate, should return 1
row, returns 2
select * from t1
where ((t1.c1 < 1 and t1.c1 > 2 ) -- Always false
predicate
or
(exists(select * from t2 where t2.c1=t1.c1)));
C1
-----------
5
5
2 record(s) selected.
-- Same query without "always false" predicate, correctly
returns 1 row
select * from t1
where exists(select * from t2 where t2.c1=t1.c1);
C1
-----------
5
1 record(s) selected. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Db2 version 11.1.4.6 *
**************************************************************** |
| Local Fix: |
|
| Solution |
|
| Workaround |
****************************************************************
* USERS AFFECTED: *
* All *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Db2 version 11.1.4.6 *
**************************************************************** |
| Comment |
Fixed in Db2 version 11.1.4.6 |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 01.12.2020
16.03.2021
29.03.2021 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
