|
Problem IC64088
|
Status: Closed |
IMPROVE USE OF STATISTICAL VIEWS WHEN 1 OR MORE TABLES JOINED AP PLY 1 OR MORE LOCAL PREDICATESON THE COLS IN VIEWS SELECT CLAU |
| product: |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 |
| Problem description: |
This fix improve the optimizer's use of statistics from views
containing joins, when one or more tables joined applies 1 or
more local predicates on the column(s) in the view's SELECT
clause and there are multiple indexes on this table. For
example:
.
view:
select F.A, F.B, F.C, D.X
from D,F
where D.PK=F.FK;
.
query:
select *
from D,F
where D.PK=F.FK
and F.A=1
and F.B in (1,2)
and D.X = 1
indexes on F(FK,A), F(FK,B), F(A), F(B)
.
Currently, the optimizer will underestimate the cost of all the
index accesses on F when F is on the inner of a NLJN and thus
could go towards the undercosted NLJN plan. The APAR will
improve this by making better use of the view's stats. |
| Problem Summary: |
This fix improve the optimizer's use of statistics from views
containing joins, when one or more tables joined applies 1 or
more local predicates on the column(s) in the view's SELECT
clause and there are multiple indexes on this table. For
example:
.
view:
select F.A, F.B, F.C, D.X
from D,F
where D.PK=F.FK;
.
query:
select *
from D,F
where D.PK=F.FK
and F.A=1
and F.B in (1,2)
and D.X = 1
indexes on F(FK,A), F(FK,B), F(A), F(B)
.
Currently, the optimizer will underestimate the cost of all the
index accesses on F when F is on the inner of a NLJN and thus
could go towards the undercosted NLJN plan. The APAR will
improve this by making better use of the view's stats. |
| Local Fix: |
|
| available fix packs: |
DB2 Version 9.7 Fix Pack 1 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 2 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 3 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 3a for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 4 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 5 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 7 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 9a for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 6 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 8 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 9 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 10 for Linux, UNIX, and Windows
|
| Solution |
module engn_sqno
fixed >= v97 fpk1 |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 22.10.2009
16.02.2010
16.02.2010 |
| Problem solved at the following versions (IBM BugInfos) |
9.7.FPk1
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 9.7.0.1
|
 |
