Github user amansinha100 commented on a diff in the pull request:
https://github.com/apache/drill/pull/368#discussion_r58624266
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/fragment/SimpleParallelizerMultiPlans.java
---
@@ -0,0 +1,222 @@
+/**
+ * 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.drill.exec.planner.fragment;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+
+import org.apache.drill.common.exceptions.ExecutionSetupException;
+import org.apache.drill.common.util.DrillStringUtils;
+import org.apache.drill.exec.ops.QueryContext;
+import org.apache.drill.exec.physical.base.Exchange;
+import org.apache.drill.exec.physical.base.FragmentRoot;
+import org.apache.drill.exec.physical.base.PhysicalOperator;
+import org.apache.drill.exec.planner.PhysicalPlanReader;
+import
org.apache.drill.exec.planner.fragment.Materializer.IndexedFragmentNode;
+import org.apache.drill.exec.proto.BitControl.PlanFragment;
+import org.apache.drill.exec.proto.BitControl.QueryContextInformation;
+import org.apache.drill.exec.proto.CoordinationProtos.DrillbitEndpoint;
+import org.apache.drill.exec.proto.ExecProtos.FragmentHandle;
+import org.apache.drill.exec.proto.UserBitShared.QueryId;
+import org.apache.drill.exec.rpc.user.UserSession;
+import org.apache.drill.exec.server.options.OptionList;
+import org.apache.drill.exec.work.QueryWorkUnit;
+import org.apache.drill.exec.work.foreman.ForemanSetupException;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.google.common.base.Preconditions;
+import com.google.common.collect.Lists;
+
+/**
+ * SimpleParallelizerMultiPlans class is an extension to SimpleParallelizer
+ * to help with getting PlanFragments for split plan.
+ * Split plan is essentially ability to create multiple physical plans
from a single logical plan
+ * to be able to run them separately.
+ * Moving functionality specific to splitting the plan to this class
+ * allows not to pollute parent class with non-authentic functionality
+ *
+ */
+public class SimpleParallelizerMultiPlans extends SimpleParallelizer {
+
+ public SimpleParallelizerMultiPlans(QueryContext context) {
+ super(context);
+ }
+
+ /**
+ * Create multiple physical plans from original query planning, it will
allow execute them eventually independently
+ * @param options
+ * @param foremanNode
+ * @param queryId
+ * @param activeEndpoints
+ * @param reader
+ * @param rootFragment
+ * @param session
+ * @param queryContextInfo
+ * @return
+ * @throws ExecutionSetupException
+ */
+ public List<QueryWorkUnit> getSplitFragments(OptionList options,
DrillbitEndpoint foremanNode, QueryId queryId,
+ Collection<DrillbitEndpoint> activeEndpoints, PhysicalPlanReader
reader, Fragment rootFragment,
+ UserSession session, QueryContextInformation queryContextInfo)
throws ExecutionSetupException {
+
+ final PlanningSet planningSet = getFragmentsHelper(activeEndpoints,
rootFragment);
+
+ return generateWorkUnits(
+ options, foremanNode, queryId, reader, rootFragment, planningSet,
session, queryContextInfo);
+ }
+
+ /**
+ * Split plan into multiple plans based on parallelization
+ * Ideally it is applicable only to plans with two major fragments:
Screen and UnionExchange
+ * But there could be cases where we can remove even multiple exchanges
like in case of "order by"
+ * End goal is to get single major fragment: Screen with chain that ends
up with a single minor fragment
+ * from Leaf Exchange. This way each plan can run independently without
any exchange involvement
+ * @param options
+ * @param foremanNode - not really applicable
+ * @param queryId
+ * @param reader
+ * @param rootNode
+ * @param planningSet
+ * @param session
+ * @param queryContextInfo
+ * @return
+ * @throws ExecutionSetupException
+ */
+ private List<QueryWorkUnit> generateWorkUnits(OptionList options,
DrillbitEndpoint foremanNode, QueryId queryId,
+ PhysicalPlanReader reader, Fragment rootNode, PlanningSet
planningSet,
+ UserSession session, QueryContextInformation queryContextInfo)
throws ExecutionSetupException {
+
+ // now we generate all the individual plan fragments and associated
assignments. Note, we need all endpoints
+ // assigned before we can materialize, so we start a new loop here
rather than utilizing the previous one.
+
+ List<QueryWorkUnit> workUnits = Lists.newArrayList();
+ int plansCount = 0;
+ DrillbitEndpoint[] endPoints = null;
+ long initialAllocation = 0;
+ long maxAllocation = 0;
+
+ final Iterator<Wrapper> iter = planningSet.iterator();
+ while (iter.hasNext()) {
+ Wrapper wrapper = iter.next();
+ Fragment node = wrapper.getNode();
+ boolean isLeafFragment = node.getReceivingExchangePairs().size() ==
0;
+ final PhysicalOperator physicalOperatorRoot = node.getRoot();
+ // get all the needed info from leaf fragment
+ if ( (physicalOperatorRoot instanceof Exchange) && isLeafFragment) {
+ // need to get info about
+ // number of minor fragments
+ // assignedEndPoints
+ // allocation
+ plansCount = wrapper.getWidth();
+ initialAllocation = (wrapper.getInitialAllocation() != 0 ) ?
wrapper.getInitialAllocation()/plansCount : 0;
+ maxAllocation = (wrapper.getMaxAllocation() != 0 ) ?
wrapper.getMaxAllocation()/plansCount : 0;
+ endPoints = new DrillbitEndpoint[plansCount];
+ for (int mfId = 0; mfId < plansCount; mfId++) {
+ endPoints[mfId] = wrapper.getAssignedEndpoint(mfId);
+ }
+ }
+ }
+ if ( plansCount == 0 ) {
+ // no exchange, return list of single QueryWorkUnit
+ workUnits.add(generateWorkUnit(options, foremanNode, queryId,
reader, rootNode, planningSet, session, queryContextInfo));
+ return workUnits;
+ }
+
+ for (Wrapper wrapper : planningSet) {
+ Fragment node = wrapper.getNode();
+ final PhysicalOperator physicalOperatorRoot = node.getRoot();
+ if ( physicalOperatorRoot instanceof Exchange ) {
+ // get to 0 MajorFragment
+ continue;
+ }
+ boolean isRootNode = rootNode == node;
+
+ if (isRootNode && wrapper.getWidth() != 1) {
+ throw new ForemanSetupException(String.format("Failure while
trying to setup fragment. " +
+ "The root fragment must always have parallelization one.
In the current case, the width was set to %d.",
+ wrapper.getWidth()));
+ }
+ // this fragment is always leaf, as we are removing all the exchanges
+ boolean isLeafFragment = true;
+
+ // Create a minorFragment for each major fragment.
+ for (int minorFragmentId = 0; minorFragmentId < plansCount;
minorFragmentId++) {
+ // those fragments should be empty
+ List<PlanFragment> fragments = Lists.newArrayList();
+
+ PlanFragment rootFragment = null;
+ FragmentRoot rootOperator = null;
+
+ IndexedFragmentNode iNode = new
IndexedFragmentNode(minorFragmentId, wrapper);
+ wrapper.resetAllocation();
+ // two visitors here
+ // 1. To remove exchange
+ // 2. To reset operator IDs as exchanges were removed
+ PhysicalOperator op =
physicalOperatorRoot.accept(ExchangeManipulatorMaterializerVisitor.INSTANCE,
iNode).
--- End diff --
In this case, if the Exchange remover visitor did not drop any exchanges,
then the OperatorId visitor should not be called. Can you add a check for that
?
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