/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.hadoop.hive.ql.parse; import static org.apache.hadoop.hive.ql.plan.ReduceSinkDesc.ReducerTraits.AUTOPARALLEL; import static org.apache.hadoop.hive.ql.plan.ReduceSinkDesc.ReducerTraits.UNIFORM; import java.util.*; import org.apache.hadoop.fs.Path; import org.apache.hadoop.hive.conf.HiveConf; import org.apache.hadoop.hive.ql.exec.AppMasterEventOperator; import org.apache.hadoop.hive.ql.exec.FetchTask; import org.apache.hadoop.hive.ql.exec.FileSinkOperator; import org.apache.hadoop.hive.ql.exec.FilterOperator; import org.apache.hadoop.hive.ql.exec.HashTableDummyOperator; import org.apache.hadoop.hive.ql.exec.MapJoinOperator; import org.apache.hadoop.hive.ql.exec.Operator; import org.apache.hadoop.hive.ql.exec.OperatorUtils; import org.apache.hadoop.hive.ql.exec.ReduceSinkOperator; import org.apache.hadoop.hive.ql.exec.SerializationUtilities; import org.apache.hadoop.hive.ql.exec.TableScanOperator; import org.apache.hadoop.hive.ql.exec.UnionOperator; import org.apache.hadoop.hive.ql.exec.Utilities; import org.apache.hadoop.hive.ql.lib.*; import org.apache.hadoop.hive.ql.optimizer.GenMapRedUtils; import org.apache.hadoop.hive.ql.plan.*; import org.apache.hadoop.hive.ql.plan.TezEdgeProperty.EdgeType; import org.apache.hadoop.hive.ql.udf.generic.GenericUDFBetween; import org.apache.hadoop.hive.ql.udf.generic.GenericUDFInBloomFilter; import org.apache.hadoop.hive.serde2.typeinfo.TypeInfoFactory; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.google.common.collect.BiMap; import com.google.common.collect.HashBiMap; /** * GenTezUtils is a collection of shared helper methods to produce TezWork. * All the methods in this class should be static, but some aren't; this is to facilitate testing. * Methods are made non-static on as needed basis. */ public class GenTezUtils { static final private Logger LOG = LoggerFactory.getLogger(GenTezUtils.class); public GenTezUtils() { } public static UnionWork createUnionWork( GenTezProcContext context, Operator<?> root, Operator<?> leaf, TezWork tezWork) { UnionWork unionWork = new UnionWork("Union "+ context.nextSequenceNumber()); context.rootUnionWorkMap.put(root, unionWork); context.unionWorkMap.put(leaf, unionWork); tezWork.add(unionWork); return unionWork; } public static ReduceWork createReduceWork( GenTezProcContext context, Operator<?> root, TezWork tezWork) { assert !root.getParentOperators().isEmpty(); boolean isAutoReduceParallelism = context.conf.getBoolVar(HiveConf.ConfVars.TEZ_AUTO_REDUCER_PARALLELISM); float maxPartitionFactor = context.conf.getFloatVar(HiveConf.ConfVars.TEZ_MAX_PARTITION_FACTOR); float minPartitionFactor = context.conf.getFloatVar(HiveConf.ConfVars.TEZ_MIN_PARTITION_FACTOR); long bytesPerReducer = context.conf.getLongVar(HiveConf.ConfVars.BYTESPERREDUCER); ReduceWork reduceWork = new ReduceWork(Utilities.REDUCENAME + context.nextSequenceNumber()); LOG.debug("Adding reduce work (" + reduceWork.getName() + ") for " + root); reduceWork.setReducer(root); reduceWork.setNeedsTagging(GenMapRedUtils.needsTagging(reduceWork)); // All parents should be reduce sinks. We pick the one we just walked // to choose the number of reducers. In the join/union case they will // all be -1. In sort/order case where it matters there will be only // one parent. assert context.parentOfRoot instanceof ReduceSinkOperator; ReduceSinkOperator reduceSink = (ReduceSinkOperator) context.parentOfRoot; reduceWork.setNumReduceTasks(reduceSink.getConf().getNumReducers()); reduceWork.setSlowStart(reduceSink.getConf().isSlowStart()); reduceWork.setUniformDistribution(reduceSink.getConf().getReducerTraits().contains(UNIFORM)); if (isAutoReduceParallelism && reduceSink.getConf().getReducerTraits().contains(AUTOPARALLEL)) { // configured limit for reducers final int maxReducers = context.conf.getIntVar(HiveConf.ConfVars.MAXREDUCERS); // estimated number of reducers final int nReducers = reduceSink.getConf().getNumReducers(); // TODO# HERE // min we allow tez to pick int minPartition = Math.max(1, (int) (nReducers * minPartitionFactor)); minPartition = (minPartition > maxReducers) ? maxReducers : minPartition; // max we allow tez to pick int maxPartition = Math.max(1, (int) (nReducers * maxPartitionFactor)); maxPartition = (maxPartition > maxReducers) ? maxReducers : maxPartition; // reduce only if the parameters are significant if (minPartition < maxPartition && nReducers * minPartitionFactor >= 1.0) { reduceWork.setAutoReduceParallelism(true); reduceWork.setMinReduceTasks(minPartition); reduceWork.setMaxReduceTasks(maxPartition); } else if (nReducers < maxPartition) { // the max is good, the min is too low reduceWork.setNumReduceTasks(maxPartition); } } setupReduceSink(context, reduceWork, reduceSink); tezWork.add(reduceWork); TezEdgeProperty edgeProp; EdgeType edgeType = determineEdgeType(context.preceedingWork, reduceWork, reduceSink); if (reduceWork.isAutoReduceParallelism()) { edgeProp = new TezEdgeProperty(context.conf, edgeType, true, reduceWork.isSlowStart(), reduceWork.getMinReduceTasks(), reduceWork.getMaxReduceTasks(), bytesPerReducer); } else { edgeProp = new TezEdgeProperty(edgeType); edgeProp.setSlowStart(reduceWork.isSlowStart()); } reduceWork.setEdgePropRef(edgeProp); tezWork.connect( context.preceedingWork, reduceWork, edgeProp); context.connectedReduceSinks.add(reduceSink); return reduceWork; } private static void setupReduceSink( GenTezProcContext context, ReduceWork reduceWork, ReduceSinkOperator reduceSink) { LOG.debug("Setting up reduce sink: " + reduceSink + " with following reduce work: " + reduceWork.getName()); // need to fill in information about the key and value in the reducer GenMapRedUtils.setKeyAndValueDesc(reduceWork, reduceSink); // remember which parent belongs to which tag int tag = reduceSink.getConf().getTag(); reduceWork.getTagToInput().put(tag == -1 ? 0 : tag, context.preceedingWork.getName()); // remember the output name of the reduce sink reduceSink.getConf().setOutputName(reduceWork.getName()); } public MapWork createMapWork(GenTezProcContext context, Operator<?> root, TezWork tezWork, PrunedPartitionList partitions) throws SemanticException { assert root.getParentOperators().isEmpty(); MapWork mapWork = new MapWork(Utilities.MAPNAME + context.nextSequenceNumber()); LOG.debug("Adding map work (" + mapWork.getName() + ") for " + root); // map work starts with table scan operators assert root instanceof TableScanOperator; TableScanOperator ts = (TableScanOperator) root; String alias = ts.getConf().getAlias(); setupMapWork(mapWork, context, partitions, ts, alias); if (ts.getConf().getTableMetadata() != null && ts.getConf().getTableMetadata().isDummyTable()) { mapWork.setDummyTableScan(true); } if (ts.getConf().getNumBuckets() > 0) { mapWork.setIncludedBuckets(ts.getConf().getIncludedBuckets()); } // add new item to the tez work tezWork.add(mapWork); return mapWork; } // this method's main use is to help unit testing this class protected void setupMapWork(MapWork mapWork, GenTezProcContext context, PrunedPartitionList partitions, TableScanOperator root, String alias) throws SemanticException { // All the setup is done in GenMapRedUtils GenMapRedUtils.setMapWork(mapWork, context.parseContext, context.inputs, partitions, root, alias, context.conf, false); // we also collect table stats while collecting column stats. if (context.parseContext.getAnalyzeRewrite() != null) { mapWork.setGatheringStats(true); } } // removes any union operator and clones the plan public static void removeUnionOperators(GenTezProcContext context, BaseWork work, int indexForTezUnion) throws SemanticException { List<Operator<?>> roots = new ArrayList<Operator<?>>(); roots.addAll(work.getAllRootOperators()); if (work.getDummyOps() != null) { roots.addAll(work.getDummyOps()); } roots.addAll(context.eventOperatorSet); // need to clone the plan. List<Operator<?>> newRoots = SerializationUtilities.cloneOperatorTree(roots, indexForTezUnion); // we're cloning the operator plan but we're retaining the original work. That means // that root operators have to be replaced with the cloned ops. The replacement map // tells you what that mapping is. BiMap<Operator<?>, Operator<?>> replacementMap = HashBiMap.create(); // there's some special handling for dummyOps required. Mapjoins won't be properly // initialized if their dummy parents aren't initialized. Since we cloned the plan // we need to replace the dummy operators in the work with the cloned ones. List<HashTableDummyOperator> dummyOps = new LinkedList<HashTableDummyOperator>(); Iterator<Operator<?>> it = newRoots.iterator(); for (Operator<?> orig: roots) { Set<FileSinkOperator> fsOpSet = OperatorUtils.findOperators(orig, FileSinkOperator.class); for (FileSinkOperator fsOp : fsOpSet) { context.fileSinkSet.remove(fsOp); } Operator<?> newRoot = it.next(); replacementMap.put(orig, newRoot); if (newRoot instanceof HashTableDummyOperator) { // dummy ops need to be updated to the cloned ones. dummyOps.add((HashTableDummyOperator) newRoot); it.remove(); } else if (newRoot instanceof AppMasterEventOperator) { // event operators point to table scan operators. When cloning these we // need to restore the original scan. if (newRoot.getConf() instanceof DynamicPruningEventDesc) { TableScanOperator ts = ((DynamicPruningEventDesc) orig.getConf()).getTableScan(); if (ts == null) { throw new AssertionError("No table scan associated with dynamic event pruning. " + orig); } ((DynamicPruningEventDesc) newRoot.getConf()).setTableScan(ts); } it.remove(); } else { if (newRoot instanceof TableScanOperator) { if (context.tsToEventMap.containsKey(orig)) { // we need to update event operators with the cloned table scan for (AppMasterEventOperator event : context.tsToEventMap.get(orig)) { ((DynamicPruningEventDesc) event.getConf()).setTableScan((TableScanOperator) newRoot); } } // This TableScanOperator could be part of semijoin optimization. Map<ReduceSinkOperator, SemiJoinBranchInfo> rsToSemiJoinBranchInfo = context.parseContext.getRsToSemiJoinBranchInfo(); for (ReduceSinkOperator rs : rsToSemiJoinBranchInfo.keySet()) { SemiJoinBranchInfo sjInfo = rsToSemiJoinBranchInfo.get(rs); if (sjInfo.getTsOp() == orig) { SemiJoinBranchInfo newSJInfo = new SemiJoinBranchInfo( (TableScanOperator)newRoot, sjInfo.getIsHint()); rsToSemiJoinBranchInfo.put(rs, newSJInfo); } } } context.rootToWorkMap.remove(orig); context.rootToWorkMap.put(newRoot, work); } } // now we remove all the unions. we throw away any branch that's not reachable from // the current set of roots. The reason is that those branches will be handled in // different tasks. Deque<Operator<?>> operators = new LinkedList<Operator<?>>(); operators.addAll(newRoots); Set<Operator<?>> seen = new HashSet<Operator<?>>(); while(!operators.isEmpty()) { Operator<?> current = operators.pop(); seen.add(current); if (current instanceof FileSinkOperator) { FileSinkOperator fileSink = (FileSinkOperator)current; // remember it for additional processing later context.fileSinkSet.add(fileSink); FileSinkDesc desc = fileSink.getConf(); Path path = desc.getDirName(); List<FileSinkDesc> linked; if (!context.linkedFileSinks.containsKey(path)) { linked = new ArrayList<FileSinkDesc>(); context.linkedFileSinks.put(path, linked); } linked = context.linkedFileSinks.get(path); linked.add(desc); desc.setDirName(new Path(path, "" + linked.size())); desc.setLinkedFileSink(true); desc.setParentDir(path); desc.setLinkedFileSinkDesc(linked); } if (current instanceof AppMasterEventOperator) { // remember for additional processing later context.eventOperatorSet.add((AppMasterEventOperator) current); // mark the original as abandoned. Don't need it anymore. context.abandonedEventOperatorSet.add((AppMasterEventOperator) replacementMap.inverse() .get(current)); } if (current instanceof UnionOperator) { Operator<?> parent = null; int count = 0; for (Operator<?> op: current.getParentOperators()) { if (seen.contains(op)) { ++count; parent = op; } } // we should have been able to reach the union from only one side. assert count <= 1; if (parent == null) { // root operator is union (can happen in reducers) replacementMap.put(current, current.getChildOperators().get(0)); } else { parent.removeChildAndAdoptItsChildren(current); } } if (current instanceof FileSinkOperator || current instanceof ReduceSinkOperator) { current.setChildOperators(null); } else { operators.addAll(current.getChildOperators()); } } LOG.debug("Setting dummy ops for work " + work.getName() + ": " + dummyOps); work.setDummyOps(dummyOps); work.replaceRoots(replacementMap); } public static void processFileSink(GenTezProcContext context, FileSinkOperator fileSink) throws SemanticException { ParseContext parseContext = context.parseContext; boolean isInsertTable = // is INSERT OVERWRITE TABLE GenMapRedUtils.isInsertInto(parseContext, fileSink); HiveConf hconf = parseContext.getConf(); boolean chDir = GenMapRedUtils.isMergeRequired(context.moveTask, hconf, fileSink, context.currentTask, isInsertTable); Path finalName = GenMapRedUtils.createMoveTask(context.currentTask, chDir, fileSink, parseContext, context.moveTask, hconf, context.dependencyTask); if (chDir) { // Merge the files in the destination table/partitions by creating Map-only merge job // If underlying data is RCFile or OrcFile, RCFileBlockMerge task or // OrcFileStripeMerge task would be created. LOG.info("using CombineHiveInputformat for the merge job"); GenMapRedUtils.createMRWorkForMergingFiles(fileSink, finalName, context.dependencyTask, context.moveTask, hconf, context.currentTask); } FetchTask fetchTask = parseContext.getFetchTask(); if (fetchTask != null && context.currentTask.getNumChild() == 0) { if (fetchTask.isFetchFrom(fileSink.getConf())) { context.currentTask.setFetchSource(true); } } } /** * processAppMasterEvent sets up the event descriptor and the MapWork. * * @param procCtx * @param event */ public static void processAppMasterEvent( GenTezProcContext procCtx, AppMasterEventOperator event) { if (procCtx.abandonedEventOperatorSet.contains(event)) { // don't need this anymore return; } DynamicPruningEventDesc eventDesc = (DynamicPruningEventDesc)event.getConf(); TableScanOperator ts = eventDesc.getTableScan(); MapWork work = (MapWork) procCtx.rootToWorkMap.get(ts); if (work == null) { throw new AssertionError("No work found for tablescan " + ts); } BaseWork enclosingWork = getEnclosingWork(event, procCtx); if (enclosingWork == null) { throw new AssertionError("Cannot find work for operator" + event); } String sourceName = enclosingWork.getName(); // store the vertex name in the operator pipeline eventDesc.setVertexName(work.getName()); eventDesc.setInputName(work.getAliases().get(0)); // store table descriptor in map-work if (!work.getEventSourceTableDescMap().containsKey(sourceName)) { work.getEventSourceTableDescMap().put(sourceName, new LinkedList<TableDesc>()); } List<TableDesc> tables = work.getEventSourceTableDescMap().get(sourceName); tables.add(event.getConf().getTable()); // store column name in map-work if (!work.getEventSourceColumnNameMap().containsKey(sourceName)) { work.getEventSourceColumnNameMap().put(sourceName, new LinkedList<String>()); } List<String> columns = work.getEventSourceColumnNameMap().get(sourceName); columns.add(eventDesc.getTargetColumnName()); if (!work.getEventSourceColumnTypeMap().containsKey(sourceName)) { work.getEventSourceColumnTypeMap().put(sourceName, new LinkedList<String>()); } List<String> columnTypes = work.getEventSourceColumnTypeMap().get(sourceName); columnTypes.add(eventDesc.getTargetColumnType()); // store partition key expr in map-work if (!work.getEventSourcePartKeyExprMap().containsKey(sourceName)) { work.getEventSourcePartKeyExprMap().put(sourceName, new LinkedList<ExprNodeDesc>()); } List<ExprNodeDesc> keys = work.getEventSourcePartKeyExprMap().get(sourceName); keys.add(eventDesc.getPartKey()); } /** * getEncosingWork finds the BaseWork any given operator belongs to. */ public static BaseWork getEnclosingWork(Operator<?> op, GenTezProcContext procCtx) { List<Operator<?>> ops = new ArrayList<Operator<?>>(); findRoots(op, ops); for (Operator<?> r : ops) { BaseWork work = procCtx.rootToWorkMap.get(r); if (work != null) { return work; } } return null; } /* * findRoots returns all root operators (in ops) that result in operator op */ private static void findRoots(Operator<?> op, List<Operator<?>> ops) { List<Operator<?>> parents = op.getParentOperators(); if (parents == null || parents.isEmpty()) { ops.add(op); return; } for (Operator<?> p : parents) { findRoots(p, ops); } } /** * Remove an operator branch. When we see a fork, we know it's time to do the removal. * @param event the leaf node of which branch to be removed */ public static void removeBranch(Operator<?> event) { Operator<?> child = event; Operator<?> curr = event; while (curr.getChildOperators().size() <= 1) { child = curr; curr = curr.getParentOperators().get(0); } curr.removeChild(child); } public static EdgeType determineEdgeType(BaseWork preceedingWork, BaseWork followingWork, ReduceSinkOperator reduceSinkOperator) { if (followingWork instanceof ReduceWork) { // Ideally there should be a better way to determine that the followingWork contains // a dynamic partitioned hash join, but in some cases (createReduceWork()) it looks like // the work must be created/connected first, before the GenTezProcContext can be updated // with the mapjoin/work relationship. ReduceWork reduceWork = (ReduceWork) followingWork; if (reduceWork.getReducer() instanceof MapJoinOperator) { MapJoinOperator joinOp = (MapJoinOperator) reduceWork.getReducer(); if (joinOp.getConf().isDynamicPartitionHashJoin()) { return EdgeType.CUSTOM_SIMPLE_EDGE; } } } if(!reduceSinkOperator.getConf().isOrdering()) { //if no sort keys are specified, use an edge that does not sort return EdgeType.CUSTOM_SIMPLE_EDGE; } return EdgeType.SIMPLE_EDGE; } public static void processDynamicSemiJoinPushDownOperator( GenTezProcContext procCtx, RuntimeValuesInfo runtimeValuesInfo, ReduceSinkOperator rs) throws SemanticException { SemiJoinBranchInfo sjInfo = procCtx.parseContext.getRsToSemiJoinBranchInfo().get(rs); List<BaseWork> rsWorkList = procCtx.childToWorkMap.get(rs); if (sjInfo == null || rsWorkList == null) { // This happens when the ReduceSink's edge has been removed by cycle // detection logic. Nothing to do here. return; } if (rsWorkList.size() != 1) { StringBuilder sb = new StringBuilder(); for (BaseWork curWork : rsWorkList) { if ( sb.length() > 0) { sb.append(", "); } sb.append(curWork.getName()); } throw new SemanticException(rs + " belongs to multiple BaseWorks: " + sb.toString()); } TableScanOperator ts = sjInfo.getTsOp(); LOG.debug("ResduceSink " + rs + " to TableScan " + ts); BaseWork parentWork = rsWorkList.get(0); BaseWork childWork = procCtx.rootToWorkMap.get(ts); // Connect parent/child work with a brodacast edge. LOG.debug("Connecting Baswork - " + parentWork.getName() + " to " + childWork.getName()); TezEdgeProperty edgeProperty = new TezEdgeProperty(EdgeType.BROADCAST_EDGE); TezWork tezWork = procCtx.currentTask.getWork(); tezWork.connect(parentWork, childWork, edgeProperty); // Set output names in ReduceSink rs.getConf().setOutputName(childWork.getName()); // Set up the dynamic values in the childWork. RuntimeValuesInfo childRuntimeValuesInfo = new RuntimeValuesInfo(); childRuntimeValuesInfo.setTableDesc(runtimeValuesInfo.getTableDesc()); childRuntimeValuesInfo.setDynamicValueIDs(runtimeValuesInfo.getDynamicValueIDs()); childRuntimeValuesInfo.setColExprs(runtimeValuesInfo.getColExprs()); childWork.setInputSourceToRuntimeValuesInfo( parentWork.getName(), childRuntimeValuesInfo); } // Functionality to remove semi-join optimization public static void removeSemiJoinOperator(ParseContext context, ReduceSinkOperator rs, TableScanOperator ts) throws SemanticException{ // Cleanup the synthetic predicate in the tablescan operator by // replacing it with "true" LOG.debug("Removing ReduceSink " + rs + " and TableScan " + ts); ExprNodeDesc constNode = new ExprNodeConstantDesc( TypeInfoFactory.booleanTypeInfo, Boolean.TRUE); DynamicValuePredicateContext filterDynamicValuePredicatesCollection = new DynamicValuePredicateContext(); FilterDesc filterDesc = ((FilterOperator)(ts.getChildOperators().get(0))).getConf(); collectDynamicValuePredicates(filterDesc.getPredicate(), filterDynamicValuePredicatesCollection); for (ExprNodeDesc nodeToRemove : filterDynamicValuePredicatesCollection .childParentMapping.keySet()) { // Find out if this synthetic predicate belongs to the current cycle boolean skip = true; for (ExprNodeDesc expr : nodeToRemove.getChildren()) { if (expr instanceof ExprNodeDynamicValueDesc ) { String dynamicValueIdFromExpr = ((ExprNodeDynamicValueDesc) expr) .getDynamicValue().getId(); List<String> dynamicValueIdsFromMap = context. getRsToRuntimeValuesInfoMap().get(rs).getDynamicValueIDs(); for (String dynamicValueIdFromMap : dynamicValueIdsFromMap) { if (dynamicValueIdFromExpr.equals(dynamicValueIdFromMap)) { // Intended predicate to be removed skip = false; break; } } } } if (!skip) { ExprNodeDesc nodeParent = filterDynamicValuePredicatesCollection .childParentMapping.get(nodeToRemove); if (nodeParent == null) { // This was the only predicate, set filter expression to const filterDesc.setPredicate(constNode); } else { int i = nodeParent.getChildren().indexOf(nodeToRemove); nodeParent.getChildren().remove(i); nodeParent.getChildren().add(i, constNode); } // skip the rest of the predicates skip = true; } } context.getRsToSemiJoinBranchInfo().remove(rs); } private static class DynamicValuePredicateContext implements NodeProcessorCtx { HashMap<ExprNodeDesc, ExprNodeDesc> childParentMapping = new HashMap<ExprNodeDesc, ExprNodeDesc>(); } private static class DynamicValuePredicateProc implements NodeProcessor { @Override public Object process(Node nd, Stack<Node> stack, NodeProcessorCtx procCtx, Object... nodeOutputs) throws SemanticException { DynamicValuePredicateContext ctx = (DynamicValuePredicateContext) procCtx; ExprNodeDesc parent = (ExprNodeDesc) stack.get(stack.size() - 2); if (parent instanceof ExprNodeGenericFuncDesc) { ExprNodeGenericFuncDesc parentFunc = (ExprNodeGenericFuncDesc) parent; if (parentFunc.getGenericUDF() instanceof GenericUDFBetween || parentFunc.getGenericUDF() instanceof GenericUDFInBloomFilter) { ExprNodeDesc grandParent = stack.size() >= 3 ? (ExprNodeDesc) stack.get(stack.size() - 3) : null; ctx.childParentMapping.put(parentFunc, grandParent); } } return null; } } private static void collectDynamicValuePredicates(ExprNodeDesc pred, NodeProcessorCtx ctx) throws SemanticException { // create a walker which walks the tree in a DFS manner while maintaining // the operator stack. The dispatcher // generates the plan from the operator tree Map<Rule, NodeProcessor> exprRules = new LinkedHashMap<Rule, NodeProcessor>(); exprRules.put(new RuleRegExp("R1", ExprNodeDynamicValueDesc.class.getName() + "%"), new DynamicValuePredicateProc()); Dispatcher disp = new DefaultRuleDispatcher(null, exprRules, ctx); GraphWalker egw = new DefaultGraphWalker(disp); List<Node> startNodes = new ArrayList<Node>(); startNodes.add(pred); egw.startWalking(startNodes, null); } }