|
Problem IC72530
|
Status: Closed |
POOR PERFORMANCE WHEN LIKE PREDICATE HAS MIXED GRAPHIC AND NON-GRAPHIC ARGUMENTS |
| product: |
DB2 FOR LUW / DB2FORLUW / 950 - DB2 |
| Problem description: |
A LIKE predicate with an escape-expression does not use an
available index when the match-expression is a GRAPHIC or
VARGRAPHIC column, and both the pattern-expression and
escape-expression are CHAR or VARCHAR type. For example:
... WHERE graphiccol LIKE 'abc!_%' ESCAPE '!'
Any index on column graphiccol will not be exploited possibly
resulting in poor query performance. This only applies to a
unicode database, since mixing of graphic and non-graphic types
is not allowed otherwise. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* ALL *
****************************************************************
* PROBLEM DESCRIPTION: *
* A LIKE predicate with an escape-expression does not use an *
* available index when the match-expression is a GRAPHIC or *
* VARGRAPHIC column, and both the pattern-expression and *
* escape-expression are CHAR or VARCHAR type. For example: *
* *
* *
* *
* ... WHERE graphiccol LIKE 'abc!_%' ESCAPE '!' *
* *
* *
* *
* Any index on column graphiccol will not be exploited *
* possibly resulting in poor query performance. This only *
* applies to a unicode database, since mixing of graphic and *
* non-graphic types is not allowed otherwise. *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 Version 9.5 and Fix Pack 8 *
**************************************************************** |
| Local Fix: |
Cast the pattern-expression and/or escape-expression to graphic
type. For constants, a G prefix can be added:
... WHERE graphiccol LIKE G'abc!_%' ESCAPE G'!' |
| available fix packs: |
DB2 Version 9.5 Fix Pack 8 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 9 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 10 for Linux, UNIX, and Windows
|
| Solution |
Problem was first fixed in DB2 Version 9.5 and Fix Pack 8 |
| Workaround |
not known / see Local fix |
| BUG-Tracking |
forerunner : APAR is sysrouted TO one or more of the following: IC72599 IC72600
follow-up : |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 11.11.2010
27.06.2011
27.06.2011 |
| Problem solved at the following versions (IBM BugInfos) |
9.5.
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 9.5.0.8
|
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