Fixes are available
APAR status
Closed as program error.
Error description
A performance degradation in Db2 V11.1 M4FP4 can be observed when joining VARCHAR columns in BLU queries on AIX. Compared Db2 V11.1 M4FP4 to Db2 V11.1 M3FP3, the degradation reduced query performance up to 20-30%. If you analysis such queries using tprof, you can find ibm_cde::services::ManagedStringBase::assign very close to the top. A sample tprof output of a query affected by this issue: ... Total Ticks For All Processes (/db2/m3_1109/lib64/libdb2blu.a[shr_64.o]) = 18097 Subroutine Ticks % Source Address Bytes ========== ===== ====== ====== ======= ===== .ibm_cde::query::ConcatEvaluator::computeListOfNotCodeableInputs (bool&,ibm_cde::types::BitString&,ibm_cde::query::WorkUnit&) 2561 9.82 ConcatEvaluator.cpp 4c80848 3520 .ibm_cde::services::ManagedStringBase::assign(const unsigned char*,const unsigned long) 1791 6.87 ColumnDictionaryVersionBase.cpp 1125638 200 .ibm_cde::types::VarLenString::initCompareFunc() 941 3.61 VarLenString.cpp bbceb8 2b0 .ibm_cde::types::VarLenString::formString(const char*,ibm_cde::types::DataType,unsigned short) 923 3.54 ColumnDictionaryVersionBase.cpp 110a4a8 2d0 .ibm_cde::data::ColumnDictionaryVersion<ibm_cde::types::VarLenSt ring>::decode(ibm_cde::data::QCode,ibm_cde::types::ValUncoded&) const 895 3.43 ColumnDictionaryVersionBase.cpp 1168908 360 ...
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: * * ALL * **************************************************************** * PROBLEM DESCRIPTION: * * See Error Description * **************************************************************** * RECOMMENDATION: * * Upgrade to Db2 11.1 Mod 4 Fixpack 5 or higher * ****************************************************************
Problem conclusion
First fixed in Db2 11.1 Mod 4 Fixpack 5
Temporary fix
Comments
APAR Information
APAR number
IT27216
Reported component name
DB2 FOR LUW
Reported component ID
DB2FORLUW
Reported release
B10
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2018-12-05
Closed date
2020-01-16
Last modified date
2020-01-16
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 FOR LUW
Fixed component ID
DB2FORLUW
Applicable component levels
RB10 PSN
UP
[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSEPGG","label":"DB2 for Linux- UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1","Line of Business":{"code":"LOB10","label":"Data and AI"}}]
Document Information
Modified date:
04 May 2022