|
Problem IT10683
|
Status: Closed |
DB2 MIGHT PRODUCE A SUB-OPTIMAL PLAN FOR QUERY HAVING EXISTS WITH OR ON LOCAL PREDICATE AND SUBQUERY |
| product: |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 |
| Problem description: |
DB2 will improve the performance of queries with the following
pattern:
1) The query contains one or more existential subqueries
2) The subqueries are of type IN/EXISTS/NOT EXISTS
3) One or more subqueries are involved in a single OR predicate
4) There is one or more local predicate within the same OR
predicate
Example 1:
Select * from t1 where (exists (select 1 from t2 where t1.c2 =
t2.c2) OR T1.c1 is null OR (exists (select 1 from t3 where t1.c3
= t3.c3) ))
Example 2:
Select * from t1 where (exists(select 1 from t2 where t1.c2 =
t2.c2) or (T1.c2 is null and T2.c2 is null)) |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* engn_sqnr *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 version 105 fix pack 7 *
**************************************************************** |
| Local Fix: |
|
| Solution |
The improvement is first available in DB2 version 105 fix pack 7 |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 13.08.2015
19.01.2016
19.01.2016 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 10.5.0.7
|
 |
