DB2 FOR LUW / DB2FORLUW / B50 - DB2

In some rare cases a SORT query on a columnar table can hang.
The query does not have to be very complex. Even a
straightforward sort query like INSERT .. SELECT FROM 
ORDER BY col can hang.

The stacks would be:

Threads doing the SORT:
sqloPostEDUWaitPost + 0x0098
ibm_cde::services::EventWaitPost::post(unsigned int) + 0x0080
ibm_cde::query::SortEvaluator::processInputsSynchronously() +
0x0894
ibm_cde::query::Evaluator::evaluate(bool, bool,
ibm_cde::query::Evaluator::EvaluatorRestartState&,
ibm_cde::query::OptPredicateTracker*) + 0x059c
ibm_cde::query::EvaluationRoutine::evaluate(unsigned int,
sql_static_data*) + 0x02f4
ibm_cde::query::Scheduler::evaluateChain(ibm_cde::query::Evaluat
ionRoutine*, unsigned long&, unsigned int) + 0x04d8
ibm_cde::query::Scheduler::runWorkerThread(void*, int*) + 0x0580
ibm_cde::query::cdeEntryPointImpl(sqeAgent*, void*, void*) +
0x0088
cdeInterface::startCdeSubagent(sqeAgent*) + 0x00d4
sqlriInvokeCde(sqlrr_cb*) + 0x0050

or

sqloPostEDUWaitPost + 0x0098
ibm_cde::services::EventWaitPost::post(unsigned int) + 0x0080
ibm_cde::query::SortEvaluator::processInputsSynchronously() +
0x0894
ibm_cde::query::Evaluator::evaluate(bool, bool,
ibm_cde::query::Evaluator::EvaluatorRestartState&,
ibm_cde::query::OptPredicateTracker*) + 0x059c
ibm_cde::query::EvaluationRoutine::evaluate(unsigned int,
sql_static_data*) + 0x02f4
ibm_cde::query::Scheduler::evaluateChain(ibm_cde::query::Evaluat
ionRoutine*, unsigned long&, unsigned int) + 0x04d8
ibm_cde::query::Scheduler::runWorkerThread(void*, int*) + 0x0580
ibm_cde::query::cdeEntryPointImpl(sqeAgent*, void*, void*) +
0x0088
cdeInterface::startCdeSubagent(sqeAgent*) + 0x00d4
sqlriInvokeCde(sqlrr_cb*) + 0x0050

The consumer side will be in this stack:

semtimedop + 0x0038
ibm_cde::services::EventWaitPost::wait(int, unsigned int*) +
0x0ac0
ibm_cde::query::StreamingResultIterator::consumerEventWait(unsig
ned int, ibm_cde::services::GeneralTimer&,
ibm_cde::services::DB2MonitorInterface&,
ibm_cde::services::ScopedMutex&) + 0x024c
ibm_cde::query::StreamingResultIterator::getNextVectors(std::vec
tor&,
ibm_cde::query::WorkunitMemStats*, bool, SQLO_MEM_POOL*) +
0x0f68
ibm_cde::query::LoadNestedQueryEvaluator::processInputsSynchrono
usly() + 0x13ac
ibm_cde::query::Evaluator::evaluate(bool, bool,
ibm_cde::query::Evaluator::EvaluatorRestartState&,
ibm_cde::query::OptPredicateTracker*) + 0x059c
ibm_cde::query::EvaluationRoutine::evaluate(unsigned int,
sql_static_data*) + 0x02f4
ibm_cde::query::Scheduler::evaluateChain(ibm_cde::query::Evaluat
ionRoutine*, unsigned long&, unsigned int) + 0x01c8
ibm_cde::query::Scheduler::runWorkerThread(void*, int*) + 0x0580
ibm_cde::query::cdeEntryPointImpl(sqeAgent*, void*, void*) +
0x0088

The symptom is that this SORT will never come out of this state.

****************************************************************
* USERS AFFECTED:                                              *
* Columnar SORT                                                *
****************************************************************
* PROBLEM DESCRIPTION:                                         *
* Please See Error Description and install this fix.           *
****************************************************************
* RECOMMENDATION:                                              *
* Upgrade to 11.5.6 or later                                   *
****************************************************************

Retry the SORT command.

****************************************************************
* USERS AFFECTED:                                              *
* Columnar SORT                                                *
****************************************************************
* PROBLEM DESCRIPTION:                                         *
* Please See Error Description and install this fix.           *
****************************************************************
* RECOMMENDATION:                                              *
* Upgrade to 11.5.6 or later                                   *
****************************************************************

Upgrade to 11.5.6 or later

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

30.04.2021
16.06.2021
21.06.2021