A fix is available
APAR status
Closed as program error.
Error description
Index scan can not pick up start/stop key due to missing once-only computation for string castings in SQL compiler This results in a poor query plan and poor performance of these types of queries. Reproduction: CREATE TABLE "DSC_FILE" ( "FILE_ID" CHAR(17) FOR BIT DATA NOT NULL , "OBJECT_ID" CHAR(17) FOR BIT DATA NOT NULL , "PATH" VARCHAR(64) , "FORMAT" VARCHAR(64) , "FLAGS" SMALLINT NOT NULL ) ; ALTER TABLE "DSC_FILE" ADD PRIMARY KEY ("FILE_ID"); generate 1000 rows generate runstats db2 "select format from dsc_file where file_id = CAST( CAST ( ? AS CLOB(17) ) AS CHAR ) " Reproduction: CREATE TABLE "DSC_FILE" ( "FILE_ID" CHAR(17) FOR BIT DATA NOT NULL , "OBJECT_ID" CHAR(17) FOR BIT DATA NOT NULL , "PATH" VARCHAR(64) , "FORMAT" VARCHAR(64) , "FLAGS" SMALLINT NOT NULL ) ; ALTER TABLE "DSC_FILE" ADD PRIMARY KEY ("FILE_ID"); generate 1000 rows generate runstats db2 "select format from dsc_file where file_id = CAST( CAST ( ? AS CLOB(17) ) AS CHAR ) "
Local fix
N/A
Problem summary
INDEX SCAN CAN NOT PICK UP START/STOP KEY DUE TO MISSING ONCE-ONLY COMPUTATION FOR STRING CASTINGS IN SQL COMPILER
Problem conclusion
First fixed in DB2 UPD Version 8.2, FixPak 14. The performance enhancement is not enabled by default due to the potential of getting erroneous runtime errors (APAR JR22061). To enable this performance enhancement, set the following registry value: db2set db2compopt=33882629
Temporary fix
N/A
Comments
APAR Information
APAR number
IY85488
Reported component name
DB2 UDB ESE SOL
Reported component ID
5765F4102
Reported release
820
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2006-05-30
Closed date
2008-03-13
Last modified date
2008-03-13
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
Fix information
Fixed component name
DB2 UDB ESE SOL
Fixed component ID
5765F4102
Applicable component levels
R820 PSY
UP
[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSEPGG","label":"Db2 for Linux, UNIX and Windows"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"820","Edition":"","Line of Business":{"code":"LOB10","label":"Data and AI"}}]
Document Information
Modified date:
13 March 2008