Source Code Cross Referenced for RowResultSetNode.java in  » Database-DBMS » db-derby-10.2 » org » apache » derby » impl » sql » compile » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Database DBMS » db derby 10.2 » org.apache.derby.impl.sql.compile 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:
003:           Derby - Class org.apache.derby.impl.sql.compile.RowResultSetNode
004:
005:           Licensed to the Apache Software Foundation (ASF) under one or more
006:           contributor license agreements.  See the NOTICE file distributed with
007:           this work for additional information regarding copyright ownership.
008:           The ASF licenses this file to you under the Apache License, Version 2.0
009:           (the "License"); you may not use this file except in compliance with
010:           the License.  You may obtain a copy of the License at
011:
012:              http://www.apache.org/licenses/LICENSE-2.0
013:
014:           Unless required by applicable law or agreed to in writing, software
015:           distributed under the License is distributed on an "AS IS" BASIS,
016:           WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017:           See the License for the specific language governing permissions and
018:           limitations under the License.
019:
020:         */
021:
022:        package org.apache.derby.impl.sql.compile;
023:
024:        import org.apache.derby.iapi.services.context.ContextManager;
025:
026:        import org.apache.derby.iapi.sql.compile.CompilerContext;
027:        import org.apache.derby.iapi.sql.compile.CostEstimate;
028:        import org.apache.derby.iapi.sql.compile.Optimizer;
029:        import org.apache.derby.iapi.sql.compile.OptimizableList;
030:        import org.apache.derby.iapi.sql.compile.Optimizable;
031:        import org.apache.derby.iapi.sql.compile.OptimizablePredicate;
032:        import org.apache.derby.iapi.sql.compile.OptimizablePredicateList;
033:        import org.apache.derby.iapi.sql.compile.RequiredRowOrdering;
034:        import org.apache.derby.iapi.sql.compile.RowOrdering;
035:        import org.apache.derby.iapi.sql.compile.C_NodeTypes;
036:
037:        import org.apache.derby.iapi.sql.dictionary.DataDictionary;
038:        import org.apache.derby.iapi.sql.dictionary.ConglomerateDescriptor;
039:        import org.apache.derby.iapi.sql.dictionary.TableDescriptor;
040:
041:        import org.apache.derby.iapi.sql.Activation;
042:        import org.apache.derby.iapi.sql.ResultSet;
043:        import org.apache.derby.iapi.sql.Row;
044:        import org.apache.derby.iapi.error.StandardException;
045:
046:        import org.apache.derby.impl.sql.compile.ActivationClassBuilder;
047:        import org.apache.derby.iapi.services.compiler.MethodBuilder;
048:
049:        import org.apache.derby.iapi.store.access.Qualifier;
050:
051:        import org.apache.derby.iapi.services.sanity.SanityManager;
052:
053:        import org.apache.derby.iapi.util.JBitSet;
054:        import org.apache.derby.iapi.reference.SQLState;
055:        import org.apache.derby.iapi.reference.ClassName;
056:        import org.apache.derby.iapi.services.classfile.VMOpcode;
057:
058:        import java.util.Enumeration;
059:        import java.util.Properties;
060:        import java.util.Vector;
061:
062:        /**
063:         * A RowResultSetNode represents the result set for a VALUES clause.
064:         *
065:         * @author Jerry Brenner
066:         */
067:
068:        public class RowResultSetNode extends FromTable {
069:            SubqueryList subquerys;
070:            Vector aggregateVector;
071:            OrderByList orderByList;
072:
073:            /**
074:             * Initializer for a RowResultSetNode.
075:             *
076:             * @param valuesClause	The result column list for the VALUES clause.
077:             * @param tableProperties	Properties list associated with the table
078:             */
079:            public void init(Object valuesClause, Object tableProperties) {
080:                super .init(null, tableProperties);
081:                resultColumns = (ResultColumnList) valuesClause;
082:                if (resultColumns != null)
083:                    resultColumns.markInitialSize();
084:            }
085:
086:            /**
087:             * Convert this object to a String.  See comments in QueryTreeNode.java
088:             * for how this should be done for tree printing.
089:             *
090:             * @return	This object as a String
091:             */
092:
093:            public String toString() {
094:                if (SanityManager.DEBUG) {
095:                    return "orderByList: "
096:                            + (orderByList != null ? orderByList.toString()
097:                                    : "null") + "\n" + super .toString();
098:                } else {
099:                    return "";
100:                }
101:            }
102:
103:            public String statementToString() {
104:                return "VALUES";
105:            }
106:
107:            /**
108:             * Prints the sub-nodes of this object.  See QueryTreeNode.java for
109:             * how tree printing is supposed to work.
110:             *
111:             * @param depth		The depth of this node in the tree
112:             */
113:
114:            public void printSubNodes(int depth) {
115:                if (SanityManager.DEBUG) {
116:                    super .printSubNodes(depth);
117:
118:                    if (subquerys != null) {
119:                        printLabel(depth, "subquerys: ");
120:                        subquerys.treePrint(depth + 1);
121:                    }
122:                }
123:            }
124:
125:            /*
126:             *  Optimizable interface
127:             */
128:
129:            /**
130:             * @see Optimizable#estimateCost
131:             *
132:             * @exception StandardException		Thrown on error
133:             */
134:            public CostEstimate estimateCost(OptimizablePredicateList predList,
135:                    ConglomerateDescriptor cd, CostEstimate outerCost,
136:                    Optimizer optimizer, RowOrdering rowOrdering)
137:                    throws StandardException {
138:                /*
139:                 ** Assume for now that the cost of a VALUES clause is zero, with one row
140:                 ** fetched.  Is this true, and if not, does it make a difference?
141:                 ** There's nothing to optimize in this case.
142:                 */
143:                if (costEstimate == null) {
144:                    costEstimate = optimizer.newCostEstimate();
145:                }
146:
147:                costEstimate.setCost(0.0d, 1.0d, 1.0d);
148:
149:                /* A single row is always ordered */
150:                rowOrdering.optimizableAlwaysOrdered(this );
151:
152:                return costEstimate;
153:            }
154:
155:            /**
156:             * Bind the non VTI tables in this ResultSetNode.  This includes getting their
157:             * descriptors from the data dictionary and numbering them.
158:             *
159:             * @param dataDictionary	The DataDictionary to use for binding
160:             * @param fromListParam		FromList to use/append to.
161:             *
162:             * @return	ResultSetNode
163:             *
164:             * @exception StandardException		Thrown on error
165:             */
166:
167:            public ResultSetNode bindNonVTITables(
168:                    DataDictionary dataDictionary, FromList fromListParam)
169:                    throws StandardException {
170:                /* Assign the tableNumber */
171:                if (tableNumber == -1) // allow re-bind, in which case use old number
172:                    tableNumber = getCompilerContext().getNextTableNumber();
173:
174:                /* VALUES clause has no tables, so nothing to do */
175:                return this ;
176:            }
177:
178:            /**
179:             * Bind the expressions in this RowResultSetNode.  This means binding the
180:             * sub-expressions, as well as figuring out what the return type is
181:             * for each expression.
182:             *
183:             * @exception StandardException		Thrown on error
184:             */
185:
186:            public void bindExpressions(FromList fromListParam)
187:                    throws StandardException {
188:                int nestingLevel;
189:
190:                subquerys = (SubqueryList) getNodeFactory().getNode(
191:                        C_NodeTypes.SUBQUERY_LIST, getContextManager());
192:
193:                aggregateVector = new Vector();
194:
195:                /* Verify that there are no DEFAULTs in the RCL.
196:                 * DEFAULT is only valid for an insert, and it has
197:                 * already been coverted into the tree by the time we get here.
198:                 * The grammar allows:
199:                 *		VALUES DEFAULT;
200:                 * so we need to check for that here and throw an exception if found.
201:                 */
202:                resultColumns.checkForInvalidDefaults();
203:
204:                /* Believe it or not, a values clause can contain correlated column references
205:                 * and subqueries.  In order to get correlated column resolution working 
206:                 * correctly, we need to set our nesting level to be 1 deeper than the current
207:                 * level and push ourselves into the FROM list.  
208:                 */
209:
210:                /* Set the nesting level in this node */
211:                if (fromListParam.size() == 0) {
212:                    nestingLevel = 0;
213:                } else {
214:                    nestingLevel = ((FromTable) fromListParam.elementAt(0))
215:                            .getLevel() + 1;
216:                }
217:                setLevel(nestingLevel);
218:                fromListParam.insertElementAt(this , 0);
219:                resultColumns.bindExpressions(fromListParam, subquerys,
220:                        aggregateVector);
221:                // Pop ourselves back out of the FROM list
222:                fromListParam.removeElementAt(0);
223:
224:                if (aggregateVector.size() > 0) {
225:                    throw StandardException
226:                            .newException(SQLState.LANG_NO_AGGREGATES_IN_WHERE_CLAUSE);
227:                }
228:            }
229:
230:            /**
231:             * Bind the expressions in this ResultSetNode if it has tables.  This means binding the
232:             * sub-expressions, as well as figuring out what the return type is for
233:             * each expression.
234:             *
235:             * @param fromListParam		FromList to use/append to.
236:             *
237:             * @exception StandardException		Thrown on error
238:             */
239:            public void bindExpressionsWithTables(FromList fromListParam)
240:                    throws StandardException {
241:                /* We don't have any tables, so just return */
242:                return;
243:            }
244:
245:            /**
246:             * Bind the expressions in the target list.  This means binding the
247:             * sub-expressions, as well as figuring out what the return type is
248:             * for each expression.  This is useful for EXISTS subqueries, where we
249:             * need to validate the target list before blowing it away and replacing
250:             * it with a SELECT true.
251:             *
252:             * @exception StandardException		Thrown on error
253:             */
254:
255:            public void bindTargetExpressions(FromList fromListParam)
256:                    throws StandardException {
257:                bindExpressions(fromListParam);
258:            }
259:
260:            /**
261:             * Bind any untyped null nodes to the types in the given ResultColumnList.
262:             *
263:             * @param bindingRCL	The ResultColumnList with the types to bind to.
264:             *
265:             * @exception StandardException		Thrown on error
266:             */
267:            public void bindUntypedNullsToResultColumns(
268:                    ResultColumnList bindingRCL) throws StandardException {
269:                /*
270:                 ** If bindingRCL is null, then we are
271:                 ** under a cursor node that is inferring
272:                 ** its RCL from us.  It passes null to
273:                 ** get union to use both sides of the union
274:                 ** for the check.  Anyway, since there is
275:                 ** nothing under us but an RCL, just pass
276:                 ** in our RCL.
277:                 */
278:                if (bindingRCL == null)
279:                    bindingRCL = resultColumns;
280:
281:                resultColumns.bindUntypedNullsToResultColumns(bindingRCL);
282:            }
283:
284:            /**
285:             * Try to find a ResultColumn in the table represented by this FromTable
286:             * that matches the name in the given ColumnReference.
287:             *
288:             * @param columnReference	The columnReference whose name we're looking
289:             *				for in the given table.
290:             *
291:             * @return	A ResultColumn whose expression is the ColumnNode
292:             *			that matches the ColumnReference.
293:             *		Returns null if there is no match.
294:             *
295:             * @exception StandardException		Thrown on error
296:             */
297:
298:            public ResultColumn getMatchingColumn(
299:                    ColumnReference columnReference) throws StandardException {
300:                return null;
301:            }
302:
303:            /**
304:             * Get the exposed name for this table, which is the name that can
305:             * be used to refer to it in the rest of the query.
306:             *
307:             * @return	The exposed name of this table.
308:             *
309:             * @exception StandardException		Thrown on error
310:             */
311:            public String getExposedName() throws StandardException {
312:                return null;
313:            }
314:
315:            /**
316:             * Verify that a SELECT * is valid for this type of subquery.
317:             *
318:             * @param outerFromList	The FromList from the outer query block(s)
319:             * @param subqueryType	The subquery type
320:             *
321:             * @exception StandardException		Thrown on error
322:             */
323:            public void verifySelectStarSubquery(FromList outerFromList,
324:                    int subqueryType) throws StandardException {
325:                return;
326:            }
327:
328:            /**
329:             * Push the order by list down from the cursor node
330:             * into its child result set so that the optimizer
331:             * has all of the information that it needs to 
332:             * consider sort avoidance.
333:             *
334:             * @param orderByList	The order by list
335:             */
336:            void pushOrderByList(OrderByList orderByList) {
337:                this .orderByList = orderByList;
338:            }
339:
340:            /** 
341:             * Put a ProjectRestrictNode on top of each FromTable in the FromList.
342:             * ColumnReferences must continue to point to the same ResultColumn, so
343:             * that ResultColumn must percolate up to the new PRN.  However,
344:             * that ResultColumn will point to a new expression, a VirtualColumnNode, 
345:             * which points to the FromTable and the ResultColumn that is the source for
346:             * the ColumnReference.  
347:             * (The new PRN will have the original of the ResultColumnList and
348:             * the ResultColumns from that list.  The FromTable will get shallow copies
349:             * of the ResultColumnList and its ResultColumns.  ResultColumn.expression
350:             * will remain at the FromTable, with the PRN getting a new 
351:             * VirtualColumnNode for each ResultColumn.expression.)
352:             * We then project out the non-referenced columns.  If there are no referenced
353:             * columns, then the PRN's ResultColumnList will consist of a single ResultColumn
354:             * whose expression is 1.
355:             *
356:             * @param numTables			Number of tables in the DML Statement
357:             * @param gbl				The group by list, if any
358:             * @param fromList			The from list, if any
359:             *
360:             * @return The generated ProjectRestrictNode atop the original FromTable.
361:             *
362:             * @exception StandardException		Thrown on error
363:             */
364:
365:            public ResultSetNode preprocess(int numTables, GroupByList gbl,
366:                    FromList fromList) throws StandardException {
367:
368:                if (subquerys.size() > 0) {
369:                    subquerys.preprocess(numTables, (FromList) getNodeFactory()
370:                            .getNode(C_NodeTypes.FROM_LIST,
371:                                    getNodeFactory().doJoinOrderOptimization(),
372:                                    getContextManager()),
373:                            (SubqueryList) getNodeFactory().getNode(
374:                                    C_NodeTypes.SUBQUERY_LIST,
375:                                    getContextManager()),
376:                            (PredicateList) getNodeFactory().getNode(
377:                                    C_NodeTypes.PREDICATE_LIST,
378:                                    getContextManager()));
379:                }
380:
381:                /* Allocate a dummy referenced table map */
382:                referencedTableMap = new JBitSet(numTables);
383:                referencedTableMap.set(tableNumber);
384:                return this ;
385:            }
386:
387:            /**
388:             * Ensure that the top of the RSN tree has a PredicateList.
389:             *
390:             * @param numTables			The number of tables in the query.
391:             * @return ResultSetNode	A RSN tree with a node which has a PredicateList on top.
392:             *
393:             * @exception StandardException		Thrown on error
394:             */
395:            public ResultSetNode ensurePredicateList(int numTables)
396:                    throws StandardException {
397:                return genProjectRestrict(numTables);
398:            }
399:
400:            /**
401:             * Add a new predicate to the list.  This is useful when doing subquery
402:             * transformations, when we build a new predicate with the left side of
403:             * the subquery operator and the subquery's result column.
404:             *
405:             * @param predicate		The predicate to add
406:             *
407:             * @return ResultSetNode	The new top of the tree.
408:             *
409:             * @exception StandardException		Thrown on error
410:             */
411:            public ResultSetNode addNewPredicate(Predicate predicate)
412:                    throws StandardException {
413:                PredicateList predList;
414:                ResultColumnList prRCList;
415:                ResultSetNode newPRN;
416:
417:                /* We are the body of a quantified predicate subquery.  We
418:                 * need to generate (and return) a PRN above us so that there will be
419:                 * a place to attach the new predicate.
420:                 */
421:
422:                /* We get a shallow copy of the ResultColumnList and its 
423:                 * ResultColumns.  (Copy maintains ResultColumn.expression for now.)
424:                 */
425:                prRCList = resultColumns;
426:                resultColumns = resultColumns.copyListAndObjects();
427:
428:                /* Replace ResultColumn.expression with new VirtualColumnNodes
429:                 * in the ProjectRestrictNode's ResultColumnList.  (VirtualColumnNodes include
430:                 * pointers to source ResultSetNode, this, and source ResultColumn.)
431:                 */
432:                prRCList.genVirtualColumnNodes(this , resultColumns);
433:
434:                /* Put the new predicate in a list */
435:                predList = (PredicateList) getNodeFactory().getNode(
436:                        C_NodeTypes.PREDICATE_LIST, getContextManager());
437:                predList.addPredicate(predicate);
438:
439:                /* Finally, we create the new ProjectRestrictNode */
440:                return (ResultSetNode) getNodeFactory().getNode(
441:                        C_NodeTypes.PROJECT_RESTRICT_NODE, this , prRCList,
442:                        null, /* Restriction */
443:                        predList, /* Restriction as PredicateList */
444:                        null, /* Project subquery list */
445:                        null, /* Restrict subquery list */
446:                        tableProperties, getContextManager());
447:            }
448:
449:            /**
450:             * Evaluate whether or not the subquery in a FromSubquery is flattenable.  
451:             * Currently, a FSqry is flattenable if all of the following are true:
452:             *		o  Subquery is a SelectNode or a RowResultSetNode (not a UnionNode)
453:             *		o  It contains no top level subqueries.  (RESOLVE - we can relax this)
454:             *		o  It does not contain a group by or having clause
455:             *		o  It does not contain aggregates.
456:             *		o  There is at least one result set in the from list that is
457:             *		   not a RowResultSetNode (the reason is to avoid having
458:             *		   an outer SelectNode with an empty FromList.
459:             *
460:             * @param fromList	The outer from list
461:             *
462:             * @return boolean	Whether or not the FromSubquery is flattenable.
463:             */
464:            public boolean flattenableInFromSubquery(FromList fromList) {
465:                if ((subquerys != null) && (subquerys.size() > 0)) {
466:                    return false;
467:                }
468:
469:                if ((aggregateVector != null) && (aggregateVector.size() > 0)) {
470:                    return false;
471:                }
472:
473:                /*
474:                 ** Don't flatten if select list contains something
475:                 ** that isn't clonable
476:                 */
477:                if (!resultColumns.isCloneable()) {
478:                    return false;
479:                }
480:
481:                boolean nonRowResultSetFound = false;
482:                int flSize = fromList.size();
483:                for (int index = 0; index < flSize; index++) {
484:                    FromTable ft = (FromTable) fromList.elementAt(index);
485:
486:                    if (ft instanceof  FromSubquery) {
487:                        ResultSetNode subq = ((FromSubquery) ft).getSubquery();
488:                        if (!(subq instanceof  RowResultSetNode)) {
489:                            nonRowResultSetFound = true;
490:                            break;
491:                        }
492:                    } else {
493:                        nonRowResultSetFound = true;
494:                        break;
495:                    }
496:                }
497:
498:                return nonRowResultSetFound;
499:            }
500:
501:            /**
502:             * Optimize this SelectNode.  This means choosing the best access path
503:             * for each table, among other things.
504:             *
505:             * @param dataDictionary	The DataDictionary to use for optimization
506:             * @param predicateList		The predicate list to optimize against
507:             * @param outerRows			The number of outer joining rows
508:             *
509:             * @return	ResultSetNode	The top of the optimized tree
510:             *
511:             * @exception StandardException		Thrown on error
512:             */
513:            public ResultSetNode optimize(DataDictionary dataDictionary,
514:                    PredicateList predicateList, double outerRows)
515:                    throws StandardException {
516:                /*
517:                 ** Get an optimizer.  The only reason we need one is to get a
518:                 ** CostEstimate object, so we can represent the cost of this node.
519:                 ** This seems like overkill, but it's just an object allocation...
520:                 */
521:                Optimizer optimizer = getOptimizer((FromList) getNodeFactory()
522:                        .getNode(C_NodeTypes.FROM_LIST,
523:                                getNodeFactory().doJoinOrderOptimization(),
524:                                getContextManager()), predicateList,
525:                        dataDictionary, (RequiredRowOrdering) null);
526:                costEstimate = optimizer.newCostEstimate();
527:
528:                // RESOLVE: THE COST SHOULD TAKE SUBQUERIES INTO ACCOUNT
529:                costEstimate.setCost(0.0d, outerRows, outerRows);
530:
531:                subquerys.optimize(dataDictionary, outerRows);
532:                return this ;
533:            }
534:
535:            /**
536:             * @see Optimizable#modifyAccessPath
537:             *
538:             * @exception StandardException		Thrown on error
539:             */
540:            public Optimizable modifyAccessPath(JBitSet outerTables)
541:                    throws StandardException {
542:                /* For most types of Optimizable, do nothing */
543:                return (Optimizable) modifyAccessPaths();
544:            }
545:
546:            /**
547:             * @see ResultSetNode#modifyAccessPaths
548:             *
549:             * @exception StandardException		Thrown on error
550:             */
551:            public ResultSetNode modifyAccessPaths() throws StandardException {
552:                ResultSetNode treeTop = this ;
553:
554:                subquerys.modifyAccessPaths();
555:
556:                /* Generate the OrderByNode if a sort is still required for
557:                 * the order by.
558:                 */
559:                if (orderByList != null) {
560:                    treeTop = (ResultSetNode) getNodeFactory().getNode(
561:                            C_NodeTypes.ORDER_BY_NODE, treeTop, orderByList,
562:                            tableProperties, getContextManager());
563:                }
564:                return treeTop;
565:            }
566:
567:            /**
568:             * Return whether or not this ResultSet tree is guaranteed to return
569:             * at most 1 row based on heuristics.  (A RowResultSetNode and a
570:             * SELECT with a non-grouped aggregate will return at most 1 row.)
571:             *
572:             * @return Whether or not this ResultSet tree is guaranteed to return
573:             * at most 1 row based on heuristics.
574:             */
575:            boolean returnsAtMostOneRow() {
576:                return true;
577:            }
578:
579:            /**
580:             * The generated ResultSet will be:
581:             *
582:             *      RowResultSet -- for the VALUES clause
583:             *
584:             *
585:             * @exception StandardException		Thrown on error
586:             */
587:            public void generate(ActivationClassBuilder acb, MethodBuilder mb)
588:                    throws StandardException {
589:                if (SanityManager.DEBUG)
590:                    SanityManager.ASSERT(resultColumns != null,
591:                            "Tree structure bad");
592:
593:                // Get our final cost estimate.
594:                costEstimate = getFinalCostEstimate();
595:
596:                /*
597:                 ** Check and see if everything below us is a constant or not.
598:                 ** If so, we'll let execution know that it can do some caching.
599:                 ** Before we do the check, we are going to temporarily set
600:                 */
601:                boolean canCache = canWeCacheResults();
602:
603:                /* Get the next ResultSet #, so that we can number this ResultSetNode, its
604:                 * ResultColumnList and ResultSet.
605:                 */
606:                assignResultSetNumber();
607:
608:                // we are dealing with
609:                // VALUES(value1, value2, value3)
610:                // so we generate a RowResultSet to return the values listed.
611:
612:                // we can reduce the tree to one RowResultSet
613:                // since there is nothing but the resultColumns
614:
615:                // RowResultSet takes the row-generating function
616:                // so we generate one and get back the expression
617:                // pointing to it.
618:                //
619:                // generate the expression to return, which is:
620:                // ResultSetFactory.getRowResultSet(this, planX.exprN)
621:                // [planX is the name of the class being generated,
622:                // exprN is the name of the function being generated.]
623:
624:                acb.pushGetResultSetFactoryExpression(mb);
625:
626:                acb.pushThisAsActivation(mb);
627:                resultColumns.generate(acb, mb);
628:                mb.push(canCache);
629:                mb.push(resultSetNumber);
630:                mb.push(costEstimate.rowCount());
631:                mb.push(costEstimate.getEstimatedCost());
632:                mb.callMethod(VMOpcode.INVOKEINTERFACE, (String) null,
633:                        "getRowResultSet", ClassName.NoPutResultSet, 6);
634:            }
635:
636:            /**
637:             * Replace any DEFAULTs with the associated tree for the default.
638:             *
639:             * @param ttd	The TableDescriptor for the target table.
640:             * @param tcl	The RCL for the target table.
641:             *
642:             * @exception StandardException		Thrown on error
643:             */
644:            void replaceDefaults(TableDescriptor ttd, ResultColumnList tcl)
645:                    throws StandardException {
646:                resultColumns.replaceDefaults(ttd, tcl);
647:            }
648:
649:            /**
650:             * Optimize any subqueries that haven't been optimized any where
651:             * else.  This is useful for a RowResultSetNode as a derived table
652:             * because it doesn't get optimized otherwise.
653:             *
654:             * @exception StandardException		Thrown on error
655:             */
656:            void optimizeSubqueries(DataDictionary dd, double rowCount)
657:                    throws StandardException {
658:                subquerys.optimize(dd, rowCount);
659:            }
660:
661:            /**
662:             * Notify the underlying result set tree that the result is
663:             * ordering dependent.  (For example, no bulk fetch on an index
664:             * if under an IndexRowToBaseRow.)
665:             */
666:            void markOrderingDependent() {
667:            }
668:
669:            /*
670:             ** Check and see if everything below us is a constant or not.
671:             ** If so, we'll let execution know that it can do some caching.
672:             ** Before we do the check, we are going to temporarily set
673:             ** ParameterNodes to CONSTANT.  We do this because we know
674:             ** that we can cache a row with a parameter value and get
675:             ** the param column reset by the user setting a param, so
676:             ** we can skip over parameter nodes.  We are doing this
677:             ** extra work to optimize inserts of the form:
678:             **
679:             ** prepare: insert into mytab values (?,?);
680:             ** setParam
681:             ** execute()
682:             ** setParam
683:             ** execute()
684:             */
685:            private boolean canWeCacheResults() throws StandardException {
686:
687:                /*
688:                 ** Check the tree below us
689:                 */
690:                HasVariantValueNodeVisitor visitor = new HasVariantValueNodeVisitor(
691:                        Qualifier.QUERY_INVARIANT, true);
692:
693:                super .accept(visitor);
694:                boolean canCache = !visitor.hasVariant();
695:
696:                return canCache;
697:            }
698:        }
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