| /* |
| * Copyright 2009-2013 by The Regents of the University of California |
| * Licensed 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 from |
| * |
| * 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 edu.uci.ics.hyracks.algebricks.rewriter.rules; |
| |
| import java.util.ArrayList; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Set; |
| |
| import org.apache.commons.lang3.mutable.Mutable; |
| import org.apache.commons.lang3.mutable.MutableObject; |
| |
| import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException; |
| import edu.uci.ics.hyracks.algebricks.common.utils.Triple; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities; |
| import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule; |
| |
| /** |
| * Pushes an AssignOperator below a UnionAll operator by creating an new AssignOperator below each of |
| * the UnionAllOperator's branches with appropriate variable replacements. |
| * This rule can help to enable other rules that are difficult to fire across a UnionAllOperator, |
| * for example, eliminating common sub-expressions. |
| * |
| * Example: |
| * |
| * Before plan: |
| * ... |
| * assign [$$20, $$21] <- [funcA($$3), funcB($$6)] |
| * union ($$1, $$2, $$3) ($$4, $$5, $$6) |
| * union_branch_0 |
| * ... |
| * union_branch_1 |
| * ... |
| * |
| * After plan: |
| * ... |
| * union ($$1, $$2, $$3) ($$4, $$5, $$6) ($$22, $$24, $$20) ($$23, $$25, $$21) |
| * assign [$$22, $$23] <- [funcA($$1), funcB($$4)] |
| * union_branch_0 |
| * ... |
| * assign [$$24, $$25] <- [funcA($$2), funcB($$5)] |
| * union_branch_1 |
| * ... |
| */ |
| public class PushAssignBelowUnionAllRule implements IAlgebraicRewriteRule { |
| |
| @Override |
| public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException { |
| return false; |
| } |
| |
| @Override |
| public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) |
| throws AlgebricksException { |
| AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue(); |
| if (!op.hasInputs()) { |
| return false; |
| } |
| |
| boolean modified = false; |
| for (int i = 0; i < op.getInputs().size(); i++) { |
| AbstractLogicalOperator childOp = (AbstractLogicalOperator) op.getInputs().get(i).getValue(); |
| if (childOp.getOperatorTag() != LogicalOperatorTag.ASSIGN) { |
| continue; |
| } |
| AssignOperator assignOp = (AssignOperator) childOp; |
| |
| AbstractLogicalOperator childOfChildOp = (AbstractLogicalOperator) assignOp.getInputs().get(0).getValue(); |
| if (childOfChildOp.getOperatorTag() != LogicalOperatorTag.UNIONALL) { |
| continue; |
| } |
| UnionAllOperator unionOp = (UnionAllOperator) childOfChildOp; |
| |
| Set<LogicalVariable> assignUsedVars = new HashSet<LogicalVariable>(); |
| VariableUtilities.getUsedVariables(assignOp, assignUsedVars); |
| |
| List<LogicalVariable> assignVars = assignOp.getVariables(); |
| |
| AssignOperator[] newAssignOps = new AssignOperator[2]; |
| for (int j = 0; j < unionOp.getInputs().size(); j++) { |
| newAssignOps[j] = createAssignBelowUnionAllBranch(unionOp, j, assignOp, assignUsedVars, context); |
| } |
| // Add original assign variables to the union variable mappings. |
| for (int j = 0; j < assignVars.size(); j++) { |
| LogicalVariable first = newAssignOps[0].getVariables().get(j); |
| LogicalVariable second = newAssignOps[1].getVariables().get(j); |
| Triple<LogicalVariable, LogicalVariable, LogicalVariable> varMapping = new Triple<LogicalVariable, LogicalVariable, LogicalVariable>( |
| first, second, assignVars.get(j)); |
| unionOp.getVariableMappings().add(varMapping); |
| } |
| context.computeAndSetTypeEnvironmentForOperator(unionOp); |
| |
| // Remove original assign operator. |
| op.getInputs().set(i, assignOp.getInputs().get(0)); |
| context.computeAndSetTypeEnvironmentForOperator(op); |
| modified = true; |
| } |
| |
| return modified; |
| } |
| |
| private AssignOperator createAssignBelowUnionAllBranch(UnionAllOperator unionOp, int inputIndex, |
| AssignOperator originalAssignOp, Set<LogicalVariable> assignUsedVars, IOptimizationContext context) |
| throws AlgebricksException { |
| AssignOperator newAssignOp = cloneAssignOperator(originalAssignOp, context); |
| newAssignOp.getInputs() |
| .add(new MutableObject<ILogicalOperator>(unionOp.getInputs().get(inputIndex).getValue())); |
| context.computeAndSetTypeEnvironmentForOperator(newAssignOp); |
| unionOp.getInputs().get(inputIndex).setValue(newAssignOp); |
| int numVarMappings = unionOp.getVariableMappings().size(); |
| for (int i = 0; i < numVarMappings; i++) { |
| Triple<LogicalVariable, LogicalVariable, LogicalVariable> varMapping = unionOp.getVariableMappings().get(i); |
| if (assignUsedVars.contains(varMapping.third)) { |
| LogicalVariable replacementVar; |
| if (inputIndex == 0) { |
| replacementVar = varMapping.first; |
| } else { |
| replacementVar = varMapping.second; |
| } |
| VariableUtilities.substituteVariables(newAssignOp, varMapping.third, replacementVar, context); |
| } |
| } |
| return newAssignOp; |
| } |
| |
| /** |
| * Clones the given assign operator changing the returned variables to be new ones. |
| * Also, leaves the inputs of the clone clear. |
| */ |
| private AssignOperator cloneAssignOperator(AssignOperator assignOp, IOptimizationContext context) { |
| List<LogicalVariable> vars = new ArrayList<LogicalVariable>(); |
| List<Mutable<ILogicalExpression>> exprs = new ArrayList<Mutable<ILogicalExpression>>(); |
| int numVars = assignOp.getVariables().size(); |
| for (int i = 0; i < numVars; i++) { |
| vars.add(context.newVar()); |
| exprs.add(new MutableObject<ILogicalExpression>(assignOp.getExpressions().get(i).getValue() |
| .cloneExpression())); |
| } |
| AssignOperator assignCloneOp = new AssignOperator(vars, exprs); |
| assignCloneOp.setExecutionMode(assignOp.getExecutionMode()); |
| return assignCloneOp; |
| } |
| } |