Exception (or crash) when executing an XmlModify with multiple remove exprs

Question

Hi all,
The following code snippet resembles my execution path for updating some nodes in a document.
    XmlManager manager = DbController::getInstance()->getManager();
    XmlContainer container = DbController::getInstance()->getContainer();
    XmlTransaction mainTransaction = manager.createTransaction(DB_TXN_NOWAIT);
    XmlQueryContext queryContext = manager.createQueryContext();
    XmlTransaction childTransaction = mainTrContext->getXmlTransaction().createChild();
    XmlDocument document = container.getDocument(childTransaction, "mydocdir/docname", 0);
    childTransaction.commit();
    XmlValue nodeXmlValue;
    XmlQueryExpression docNodeExpression = manager.prepare(mainTransaction, "/acquisitionProtocol", queryContext
    XmlResults resultList = docNodeExpression.execute(mainTransaction, mainTrContext->getDocument()->getXmlValue(), queryContext
    if (resultList.size() > 0)
        resultList.next(nodeXmlValue);   
//                        XmlValue nodeXmlValue(mainTrContext->getDocument()->getXmlDocument());
    XmlUpdateContext updateContext = manager.createUpdateContext();
    XmlModify modifier = manager.createModify();
    XmlQueryExpression nodeQueryExpression = manager.prepare(mainTransaction, "./location", queryContext);
    modifier.addRemoveStep(nodeQueryExpression);
    XmlQueryExpression nodeQueryExpression = manager.prepare(mainTransaction, "./id", queryContext);
    modifier.addRemoveStep(nodeQueryExpression);
    nodeQueryExpression = manager.prepare(mainTransaction, ".", queryContext);
    modifier.addAppendStep(nodeQueryExpression, XmlModify::Element, "location", "yves/test", 0);
    modifier.execute(mainTransaction, nodeXmlValue, queryContext, updateContext);
    mainTransaction.commit();When I execute the modifier (2de last line) it throws the following exception or crashes:
DBcursor->get: DB_READ_COMMITTED, DB_READ_UNCOMMITTED and DB_RMW require locking
Exception code: 5
Error text:Error: Invalid argument File: NsEventReader.cpp Line: 828
DbErrno: 22The problem occurs when adding more than one remove expression to the modify object. If I use only one remove expression, the code works fine.
However, I can add multiple append expression without problems.
What am I doing wrong here???
Thanks in advance
Yves
Edited by: ywillems on Dec 10, 2008 7:55 AM
Edited by: ywillems on Dec 11, 2008 5:37 AM
Edited by: ywillems on Dec 11, 2008 7:05 AM

Answer 1

Yves,
Oddly enough I believe this is an optimizer bug that we've found and patched (but not yet officially released the patch). Try applying this patch to 2.4.16:
diff -ru dbxml-2.4.16-original/dbxml/src/dbxml/query/DecisionPointQP.cpp dbxml-2.4.16/dbxml/src/dbxml/query/DecisionPointQP.cpp
--- dbxml-2.4.16-original/dbxml/src/dbxml/query/DecisionPointQP.cpp
+++ dbxml-2.4.16/dbxml/src/dbxml/query/DecisionPointQP.cpp
@@ -1,14 +1,13 @@
// See the file LICENSE for redistribution information.
// Copyright (c) 2002,2008 Oracle.  All rights reserved.
-// $Id$
#include "../DbXmlInternal.hpp"
#include "DecisionPointQP.hpp"
#include "QueryPlanHolder.hpp"
#include "../QueryContext.hpp"
#include "../Manager.hpp"
#include "../Container.hpp"
@@ -269,17 +268,17 @@ protected:
   XPath2MemoryManager *mm_;
DecisionPointQP::ListItem *DecisionPointQP::justInTimeOptimize(int contID, DynamicContext *context)
     // **** IMPORTANT - This algorithm is very carefully arranged to avoid
     // **** deadlocks and race-conditions. Don't rearrange things unless you
     // **** know what you are doing!
+     
     // Get the runtime configuration
     DbXmlConfiguration *conf = GET_CONFIGURATION(context);
     // Lookup the container
     ScopedContainer scont((Manager&)conf->getManager(), contID, /*mustExist*/true);
     // Just-in-time optimise the QueryPlan, using a temporary memory manager for thread safety
     XPath2MemoryManagerImpl tmpMM;
@@ -349,17 +348,18 @@ void DecisionPointQP::justInTimeOptimize
     qp->staticTypingLite(context);
          OptimizationContext opt(OptimizationContext::REARRANGE, context, 0, container);
          qp = qp->optimize(opt);
          qp->logQP(opt.getLog(), "OQP", qp, opt.getPhase());
          OptimizationContext opt(OptimizationContext::ALTERNATIVES, context, 0, container);
-          qp = qp->chooseAlternative(opt, "decision point", container->getContainerID() == 0);
+          opt.setCheckForSS(container->getContainerID() == 0);
+          qp = qp->chooseAlternative(opt, "decision point");
          qp->logQP(opt.getLog(), "OQP", qp, opt.getPhase());
          OptimizationContext opt(OptimizationContext::ADD_STEPS, context, 0, container);
          qp = qp->optimize(opt);
          qp->logQP(opt.getLog(), "OQP", qp, opt.getPhase());
@@ -390,26 +390,37 @@ DecisionPointQP::DecisionPointQP(const D
       removed_(false),
       qpList_(0),
       qpListDone_(o->qpListDone_),
       compileTimeMinder_(o->compileTimeMinder_),
       compileTimeContext_(o->compileTimeContext_)
     if(arg_ != 0)
          _src.add(arg_->getStaticAnalysis());
+     
+     bool checkForSS = opt.checkForSS();
+     
+     try {
+          ListItem **li = &qpList_;
+          for(ListItem *oli = o->qpList_; oli != 0; oli = oli->next) {
+               opt.setCheckForSS(oli->container->getContainerID() == 0);
+          
+               *li = new (mm) ListItem(oli->container, 0);
+               (*li)->qp = oli->qp->chooseAlternative(opt, "decision point");
-     ListItem **li = &qpList_;
-     for(ListItem *oli = o->qpList_; oli != 0; oli = oli->next) {
-          *li = new (mm) ListItem(oli->container, 0);
-          (*li)->qp = oli->qp->chooseAlternative(opt, "decision point", oli->container->getContainerID() == 0);
+               _src.add((*li)->qp->getStaticAnalysis());
-          _src.add((*li)->qp->getStaticAnalysis());
-          li = &(*li)->next;
+               li = &(*li)->next;
+          }
+     catch(...) {
+          opt.setCheckForSS(checkForSS);
+          throw;
+     }
+     opt.setCheckForSS(checkForSS);
DecisionPointQP::DecisionPointQP(const DecisionPointQP *o, XPath2MemoryManager *mm)
     : QueryPlan(DECISION_POINT, o->getFlags(), mm),
       dps_(o->dps_ ? o->dps_->copy(mm) : 0),
       arg_(o->arg_ ? o->arg_->copy(mm) : 0),
       removed_(false),
       qpList_(0),
diff -ru dbxml-2.4.16-original/dbxml/src/dbxml/query/QueryPlan.cpp dbxml-2.4.16/dbxml/src/dbxml/query/QueryPlan.cpp
--- dbxml-2.4.16-original/dbxml/src/dbxml/query/QueryPlan.cpp
+++ dbxml-2.4.16/dbxml/src/dbxml/query/QueryPlan.cpp
@@ -1,14 +1,13 @@
// See the file LICENSE for redistribution information.
// Copyright (c) 2002,2008 Oracle.  All rights reserved.
-// $Id$
#include "../DbXmlInternal.hpp"
#include <assert.h>
#include <string.h>
#include <sstream>
#include <set>
#include <algorithm>
@@ -128,23 +127,54 @@ void QueryPlan::createAlternatives(unsig
     createCombinations(maxAlternatives, opt, combinations);
     // Generate the alternatives by applying conversion rules to the combinations
     for(QueryPlans::iterator it = combinations.begin(); it != combinations.end(); ++it) {
          (*it)->applyConversionRules(maxAlternatives, opt, alternatives);
-CostSortItem::CostSortItem(QueryPlan *qp, OperationContext &oc, QueryExecutionContext &qec)
-     : qp_(qp), cost_(qp->cost(oc, qec))
+class ContainsSequentialScan : public NodeVisitingOptimizer
+public:
+     bool run(QueryPlan *qp)
+     {
+          found = false;
+          optimizeQP(qp);
+          return found;
+     }
+
+private:
+     virtual void resetInternal() {}
+
+     virtual ASTNode *optimize(ASTNode *item)
+     {
+          // Don't look inside ASTNode objects
+          return item;
+     }
+     virtual QueryPlan *optimizeSequentialScan(SequentialScanQP *item)
+     {
+          found = true;
+          return item;
+     }
+
+     bool found;
+};
+
+CostSortItem::CostSortItem(QueryPlan *qp, OperationContext &oc, QueryExecutionContext &qec, bool checkForSS)
+     : qp_(qp), cost_(qp->cost(oc, qec)),
+       hasSS_(false)
+{
+     if(checkForSS) hasSS_ = ContainsSequentialScan().run(qp);
bool CostSortItem::operator<(const CostSortItem &o) const
+        if(hasSS_ != o.hasSS_) return !hasSS_;
+     
     if(cost_.totalPages() < o.cost_.totalPages()) return true;
     if(cost_.totalPages() > o.cost_.totalPages()) return false;
     if(cost_.pagesOverhead < o.cost_.pagesOverhead) return true;
     if(cost_.pagesOverhead > o.cost_.pagesOverhead) return false;
     return qp_ < o.qp_;
@@ -189,22 +219,22 @@ void QueryPlan::createReducedAlternative
               if(i != costSortSet.end()) {
                    (*it)->release();
                    continue;
               ++alternativesCount;
-               costSortSet.insert(CostSortItem(*it, oc, qec));
+               costSortSet.insert(CostSortItem(*it, oc, qec, opt.checkForSS()));
               if(costSortSet.size() > ALTERNATIVES_THRESHOLD) {
                    // Trim all QueryPlans outside of a factor of the cost of the lowest cost QueryPlan
                    // TBD Make the specific factor configurable - jpcs
-                    set<CostSortItem>::iterator cutPoint = costSortSet.lower_bound(costSortSet.begin()->cost_.totalPages() * cutOffFactor);
+                    set<CostSortItem>::iterator cutPoint = costSortSet.lower_bound(CostSortItem(costSortSet.begin()->cost_.totalPages() * cutOffFactor, false));
                    if(cutPoint != costSortSet.begin() && cutPoint != costSortSet.end()) {
                         for(i = cutPoint; i != costSortSet.end(); ++i) {
                              if(Log::isLogEnabled(Log::C_OPTIMIZER, Log::L_DEBUG)) {
                                   ostringstream oss;
                                   oss << "Rejected Alternative (outside cut off factor: ";
                                   oss << (costSortSet.begin()->cost_.totalPages() * cutOffFactor);
                                   oss << ")";
                                   log(qec, oss.str());
@@ -247,54 +277,27 @@ void QueryPlan::createReducedAlternative
     } else {
          for(set<CostSortItem>::iterator i = costSortSet.begin(); i != costSortSet.end(); ++i) {
               alternatives.push_back(i->qp_);
-class ContainsSequentialScan : public NodeVisitingOptimizer
+static bool betterAlternativeCost(const Cost &costA, bool ssA, const Cost &costB, bool ssB, bool checkForSS)
-public:
-     bool run(QueryPlan *qp)
-          found = false;
-          optimizeQP(qp);
-          return found;
-private:
-     virtual void resetInternal() {}
-     virtual ASTNode *optimize(ASTNode *item)
-          // Don't look inside ASTNode objects
-          return item;
-     virtual QueryPlan *optimizeSequentialScan(SequentialScanQP *item)
-          found = true;
-          return item;
-     bool found;
-static bool betterAlternativeCost(const Cost &costA, bool ssA, const Cost &costB, bool ssB, bool noSequentialScan)
-     if(ssA != ssB && noSequentialScan) return ssB;
+     if(ssA != ssB && checkForSS) return ssB;
     if(costA.totalPages() < costB.totalPages()) return true;
     if(costA.totalPages() > costB.totalPages()) return false;
     return costA.pagesOverhead < costB.pagesOverhead;
-QueryPlan *QueryPlan::chooseAlternative(OptimizationContext &opt, const char *name, bool noSequentialScan) const
+QueryPlan *QueryPlan::chooseAlternative(OptimizationContext &opt, const char *name) const
     QueryPlans combinations;
     createCombinations(MAX_ALTERNATIVES, opt, combinations);
     // TBD remove the need for QueryExecutionContext here - jpcs
     QueryExecutionContext qec(GET_CONFIGURATION(opt.getContext())->getQueryContext(),
          /*debugging*/false);
     qec.setContainerBase(opt.getContainerBase());
@@ -313,17 +316,17 @@ QueryPlan *QueryPlan::chooseAlternative(
          for(QueryPlans::iterator it = myAlts.begin(); it != myAlts.end(); ++it) {
               ++alternativesCount;
               QueryPlan *qp = (*it);
               Cost itCost = qp->cost(opt.getOperationContext(), qec);
               bool itSS = ContainsSequentialScan().run(qp);
-               if(bestQP == 0 || betterAlternativeCost(itCost, itSS, bestCost, bestSS, noSequentialScan)) {
+               if(bestQP == 0 || betterAlternativeCost(itCost, itSS, bestCost, bestSS, opt.checkForSS())) {
                    if(bestQP != 0) {
                         log(qec, "Rejected Alternative (not best)");
                         bestQP->logCost(qec, bestCost, 0);
                         bestQP->release();
                    bestQP = qp;
                    bestCost = itCost;
                    bestSS = itSS;
diff -ru dbxml-2.4.16-original/dbxml/src/dbxml/query/QueryPlan.hpp dbxml-2.4.16/dbxml/src/dbxml/query/QueryPlan.hpp
--- dbxml-2.4.16-original/dbxml/src/dbxml/query/QueryPlan.hpp
+++ dbxml-2.4.16/dbxml/src/dbxml/query/QueryPlan.hpp
@@ -1,14 +1,13 @@
// See the file LICENSE for redistribution information.
// Copyright (c) 2002,2008 Oracle.  All rights reserved.
-// $Id$
#ifndef __QUERYPLAN_HPP
#define     __QUERYPLAN_HPP
#include <vector>
#include <set>
#include <string>
@@ -60,40 +59,44 @@ public:
          REARRANGE = 2,
          ALTERNATIVES = 3,
          ADD_STEPS = 4,
          MAKE_PREDICATES = 5,
          REMOVE_REDUNDENTS = 6
     OptimizationContext(Phase ph, DynamicContext *cn, QueryPlanOptimizer *qpo, ContainerBase *c = 0)
-          : phase_(ph), context_(cn), qpo_(qpo), container_(c), isFetched_(false) {}
+          : phase_(ph), context_(cn), qpo_(qpo), container_(c), isFetched_(false), checkForSS_(false) {}
     Phase getPhase() const { return phase_; }
     DynamicContext *getContext() const { return context_; }
     XPath2MemoryManager *getMemoryManager() const;
     QueryPlanOptimizer *getQueryPlanOptimizer() const { return qpo_; }
     void setQueryPlanOptimizer(QueryPlanOptimizer *qpo) { qpo_ = qpo; }
     ContainerBase *getContainerBase() const { return container_; }
     Transaction *getTransaction() const;
     OperationContext &getOperationContext() const;
     const IndexSpecification &getIndexSpecification() const;
     const Log &getLog() const;
+     bool checkForSS() const { return checkForSS_; }
+     void setCheckForSS(bool val) { checkForSS_ = val; }
+
private:
     Phase phase_;
     DynamicContext *context_;
     QueryPlanOptimizer *qpo_;
     ContainerBase *container_;
     mutable IndexSpecification is_;
     mutable bool isFetched_;
+     bool checkForSS_;
class QueryPlan : public LocationInfo
public:
     virtual ~QueryPlan() {}
     typedef enum {
          // Index lookups
@@ -176,17 +179,17 @@ public:
     virtual const StaticAnalysis &getStaticAnalysis() const { return _src; }
     virtual QueryPlan *optimize(OptimizationContext &opt) = 0;
     virtual void createCombinations(unsigned int maxAlternatives, OptimizationContext &opt, QueryPlans &combinations) const;
     virtual void applyConversionRules(unsigned int maxAlternatives, OptimizationContext &opt, QueryPlans &alternatives);
     void createAlternatives(unsigned int maxAlternatives, OptimizationContext &opt, QueryPlans &alternatives) const;
     void createReducedAlternatives(double cutOffFactor, unsigned int maxAlternatives, OptimizationContext &opt, QueryPlans &alternatives) const;
-     QueryPlan *chooseAlternative(OptimizationContext &opt, const char *name, bool noSequentialScan = false) const;
+     QueryPlan *chooseAlternative(OptimizationContext &opt, const char *name) const;
     virtual NodeIterator *createNodeIterator(DynamicContext *context) const = 0;
     virtual Cost cost(OperationContext &context, QueryExecutionContext &qec) const = 0;
     /** Returns the QueryPlanRoot objects from the PathsQP in this QueryPlan */
     virtual void findQueryPlanRoots(QPRSet &qprset) const = 0;
     /// Returns true if it's sure. Returns false if it doesn't know
     virtual bool isSubsetOf(const QueryPlan *o) const = 0;
@@ -536,20 +539,21 @@ protected:
     ImpliedSchemaNode *isn2_;
     QPValue value2_;
     DbWrapper::Operation operation2_;
struct CostSortItem {
-     CostSortItem(double cost) : qp_(0), cost_(0, cost) {}
-     CostSortItem(QueryPlan *qp, OperationContext &oc, QueryExecutionContext &qec);
+     CostSortItem(double cost, bool hasSS) : qp_(0), cost_(0, cost), hasSS_(hasSS) {}
+     CostSortItem(QueryPlan *qp, OperationContext &oc, QueryExecutionContext &qec, bool checkForSS);
     bool operator<(const CostSortItem &o) const;
     QueryPlan *qp_;
     Cost cost_;
+     bool hasSS_;
#endif
diff -ru dbxml-2.4.16-original/dbxml/src/dbxml/query/SequentialScanQP.cpp dbxml-2.4.16/dbxml/src/dbxml/query/SequentialScanQP.cpp
--- dbxml-2.4.16-original/dbxml/src/dbxml/query/SequentialScanQP.cpp
+++ dbxml-2.4.16/dbxml/src/dbxml/query/SequentialScanQP.cpp
@@ -1,14 +1,13 @@
// See the file LICENSE for redistribution information.
// Copyright (c) 2002,2008 Oracle.  All rights reserved.
-// $Id$
#include "../DbXmlInternal.hpp"
#include "SequentialScanQP.hpp"
#include "StepQP.hpp"
#include "QueryExecutionContext.hpp"
#include "../ContainerBase.hpp"
#include "../Document.hpp"
@@ -134,16 +133,17 @@ QueryPlan *SequentialScanQP::optimize(Op
     return this;
NodeIterator *SequentialScanQP::createNodeIterator(DynamicContext *context) const
+     DBXML_ASSERT(container_->getContainerID() != 0);
     if(nodeType_ == ImpliedSchemaNode::METADATA) {
          return container_->createDocumentIterator(context, this);
     } else {
          NamedNodeIterator *result;
          if(nodeType_ == ImpliedSchemaNode::ATTRIBUTE) {
               result = container_->createAttributeIterator(context,
                                             this,
                                             nsUriID_);