|
Problem IT08277
|
Status: Closed |
DB2 MIGHT PERFORM POORLY FOR EXISTENTIAL SUBQUERY WITH COLUMN ORGANIZED TABLES AND COMPLEX OUTER SUBSELECTS |
| product: |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 |
| Problem description: |
Under rare scenarios, DB2 might produce a suboptimal query plan
when the following conditions are satisfied:
1) The query contains one or more EXISTS/IN subqueries
2) The subquery references one or more column organized tables
3) The outer query block for the subquery is complex and
contains one or more outer join, UNION ALL and Group By clauses.
eg.
with V1 as (
Select count(*), C1, C2
from T1 left join T2 on T1.C1 = T2.C1
inner join T3 on T1.C2 = T3.C2
Group By C1,C2)
Select *
from V1
where EXISTS (select 1
from Tx
where Tx.C1 = V1.C2) |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 version 10.5.0.7 *
**************************************************************** |
| Local Fix: |
|
| Solution |
Fixed in DB2 version 10.5.0.7 |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 13.04.2015
05.02.2016
05.02.2016 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 10.5.0.7
|
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