DB2 - Problem description
Problem IT27216 | Status: Closed |
PERFORMANCE REGRESSION IN BLU QUERIES CONTAINING JOIN ON VARCHARCOLUMNS ON AIX | |
product: | |
DB2 FOR LUW / DB2FORLUW / B10 - DB2 | |
Problem 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::decode(ibm_cde::data::QCode,ibm_cde::types::ValUncoded&) const 895 3.43 ColumnDictionaryVersionBase.cpp 1168908 360 ... | |
Problem Summary: | |
**************************************************************** * USERS AFFECTED: * * ALL * **************************************************************** * PROBLEM DESCRIPTION: * * See Error Description * **************************************************************** * RECOMMENDATION: * * Upgrade to Db2 11.1 Mod 4 Fixpack 5 or higher * **************************************************************** | |
Local Fix: | |
Solution | |
Workaround | |
not known / see Local fix | |
Timestamps | |
Date - problem reported : Date - problem closed : Date - last modified : | 05.12.2018 16.01.2020 16.01.2020 |
Problem solved at the following versions (IBM BugInfos) | |
Problem solved according to the fixlist(s) of the following version(s) |