|
Problem IC63995
|
Status: Closed |
VERY SLOW QUERY DUE TO CORRELATED HSJN ON THE INNER OF NLJN |
| product: |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 |
| Problem description: |
Query runs very slow due to a correlated HSJN on the inner of
a NLJN.
Example :
0.306141
NLJOIN
( 16)
1.03309e+07
199966
/--------------+----------\
5.9579e+07 5.1384e-09
IXSCAN HSJOIN
( 17) ( 18)
310054 78.8668
199957 9.04414
| /---------+----------\
5.9579e+07 1
INDEX: GRPBY
<schema.inx1> ( 27)
Q7 35.0439
4.02207
|
2.55873
FETCH
( 28)
35.0435
4.02207
/---+---\
2.55873 1.52447e+08
IXSCAN TABLE:
( 29) <schema.tab1>
26.1437 Q9
3
|
1.52447e+08
INDEX:
<schema.inx2>
Q9
Example of optimized part of SQL :
(SELECT MIN(Q10.$C0)
FROM
(SELECT Q9.<col1>
FROM <schema.tab1> AS Q9
WHERE (Q9.<col2> = Q7.<col2>)) AS Q10) AS Q11,
This is a side effect of another code fix which went in V9.1
FP5 |
| Problem Summary: |
Users Affected : Any user using V9.1 FP5 and above
Problem Summay : Please see the APAR description
Problem Solution : This is an under-estimation of the
buffer requirement which is fixed by this APAR |
| Local Fix: |
Use optimizer guideline similar to :
<OPTGUIDELINES><NLJOIN><ACCESS TABID='Q7'/><ACCESS
TABID='Q11'/></NLJOIN></OPTGUIDELINES> |
| 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 |
This APAR is fixed in V9.7 FixPak1
(CQ defect#wsdbu00548004) |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 22.10.2009
30.12.2009
30.12.2009 |
| Problem solved at the following versions (IBM BugInfos) |
9.7.
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 9.7.0.1
|
 |
