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DB2 - Problem description
| Problem IC61901 | Status: Closed |
ENABLE GENERATION OF IMPLIED IN-LIST PREDICATES FOR OR PREDICATE WHEN QUERY ON A SINGLE TABLE. | |
| product: | |
DB2 FOR LUW / DB2FORLUW / 950 - DB2 | |
| Problem description: | |
We are enabling generatiuon of implied IN-list predicates for
the OR predicate set when query on a single table. The OR
predicate is restricted to have only equal (=) and inlist (IN)
predicate subterm therefore only implied IN-list predicate would
be generated. With the new IN-list generated, we have new
opportunity to carry out IN-TO-JOIN transformation to enhance
query performance.
e.g.
select a1,a2,a3
from a
where (a1 = 1 and a3 in ('aa','bb','cc')) or (a1 = 1 and a3 in
('dd','ee')) or (a1 = 2 and a3 in ('ff'));
Optimized query:
SELECT ALL Q3.A1, Q3.A2, Q3.A3
FROM A Q3
WHERE SYSIBM.SINLIST(Q3.A3, 'aa', 'bb', 'cc', 'dd', 'ee', 'ff')
AND
SYSIBM.SINLIST(Q3.A1, 1, 2) AND
(((Q3.A1 = 1) AND SYSIBM.SINLIST(Q3.A3, 'aa', 'bb', 'cc')) OR
((Q3.A1 = 1) AND SYSIBM.SINLIST(Q3.A3, 'dd', 'ee'))) OR
((Q3.A1 = 2) AND (Q3.A3 = 'ff'));
Note that there are existing condition to carry IN-TO-JOIN
transfromation, the new IN predicate is expected to comply to
those existing condition for have IN-TO-JOIN resulted. | |
| Problem Summary: | |
ENABLE GENERATION OF IMPLIED IN-LIST PREDICATES FOR OR PREDICATE WHEN QUERY ON A SINGLE TABLE. | |
| Local Fix: | |
Workaround: You may manually rewritten the query with the implied IN predicate as shown in the example. defect: wsdbu00554342 | |
| available fix packs: | |
DB2 Version 9.5 Fix Pack 6a for Linux, UNIX, and Windows | |
| Solution | |
Problem was first fixed in Version 9.5 Fix Pack 6 | |
| Workaround | |
not known / see Local fix | |
| Timestamps | |
Date - problem reported : Date - problem closed : Date - last modified : | 08.07.2009 17.05.2010 17.05.2010 |
| Problem solved at the following versions (IBM BugInfos) | |
9.5.FP6 | |
| Problem solved according to the fixlist(s) of the following version(s) | |