|
Problem IC68939
|
Status: Closed |
PERFORMANCE ISSUE WHEN CAST AROUND LITERAL FOR BIT DATA IS PRESENT |
| product: |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 |
| Problem description: |
This problem happens ONLY WHEN CAST for BIT DATA and only when
it is on one side and not another and only when literals.
DB2 generate non-optimal plans because BIT_STRING function is
injected and it prevents certain optimization logic. Please
consider the following examples:
CAST(x'00' AS CHAR(1) FOR BIT DATA) = CAST(x'01' AS CHAR(1) FOR
BIT DATA)
- will perform well
x'00' = x'01'
- will perform well
CAST(x'00' AS CHAR(1) FOR BIT DATA) = x'01'
- here PERFROMANCE is BAD. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All *
****************************************************************
* PROBLEM DESCRIPTION: *
* This problem happens ONLY WHEN CAST for BIT DATA and *
* onlywhenit is on one side and not another and only when *
* literals.DB2 generate non-optimal plans because BIT_STRING *
* functionisinjected and it prevents certain optimization *
* logic. Pleaseconsider the following examples:CAST(x'00' AS *
* CHAR(1) FOR BIT DATA) = CAST(x'01' AS CHAR(1)FORBIT DATA)- *
* will perform wellx'00' = x'01'- will perform *
* wellCAST(x'00' AS CHAR(1) FOR BIT DATA) = x'01'- here *
* PERFROMANCE is BAD. *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 9.7 FP3 *
**************************************************************** |
| Local Fix: |
rewrite the statement in the following manner
CAST(x'00' AS CHAR(1) FOR BIT DATA) = CAST(x'01' AS CHAR(1) FOR
BIT DATA) |
| available fix packs: |
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 6 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 7 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 9a for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 10 for Linux, UNIX, and Windows
|
| Solution |
Problem was first fixed in Version 9.7 Fix Pack 3 |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 03.06.2010
19.10.2010
19.10.2010 |
| Problem solved at the following versions (IBM BugInfos) |
9.7.FP3
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 9.7.0.3
|
 |
| 9.7.0.3
|
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