| /* |
| * Copyright 2009-2010 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.LinkedList; |
| |
| import org.apache.commons.lang3.mutable.Mutable; |
| import org.apache.commons.lang3.mutable.MutableObject; |
| |
| 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.ILogicalPlan; |
| 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.expressions.ConstantExpression; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LeftOuterJoinOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.util.OperatorManipulationUtil; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.util.OperatorPropertiesUtil; |
| import edu.uci.ics.hyracks.algebricks.core.api.exceptions.AlgebricksException; |
| import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule; |
| |
| public class EliminateSubplanRule implements IAlgebraicRewriteRule { |
| |
| @Override |
| public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) { |
| return false; |
| } |
| |
| /** |
| * Eliminate Subplan above ETS |
| * |
| * and Subplan that has only ops. with one input and no free vars. (could we |
| * modify it to consider free vars which are sources of Unnest or Assign, if |
| * there are no aggregates?) |
| */ |
| @Override |
| public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException { |
| AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue(); |
| if (op.getOperatorTag() != LogicalOperatorTag.SUBPLAN) { |
| return false; |
| } |
| SubplanOperator subplan = (SubplanOperator) op; |
| |
| Mutable<ILogicalOperator> outerRef = subplan.getInputs().get(0); |
| AbstractLogicalOperator outerRefOp = (AbstractLogicalOperator) outerRef.getValue(); |
| if (outerRefOp.getOperatorTag() == LogicalOperatorTag.EMPTYTUPLESOURCE) { |
| elimSubplanOverEts(opRef, context); |
| return true; |
| } |
| if (subplan.getNestedPlans().size() == 1 && subplan.getNestedPlans().get(0).getRoots().size() == 1 |
| && !OperatorPropertiesUtil.hasFreeVariables(subplan)) { |
| if (elimOneSubplanWithNoFreeVars(opRef)) { |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| private boolean elimOneSubplanWithNoFreeVars(Mutable<ILogicalOperator> opRef) { |
| SubplanOperator subplan = (SubplanOperator) opRef.getValue(); |
| AbstractLogicalOperator rootOp = (AbstractLogicalOperator) subplan.getNestedPlans().get(0).getRoots().get(0) |
| .getValue(); |
| if (rootOp.getOperatorTag() == LogicalOperatorTag.EMPTYTUPLESOURCE) { |
| opRef.setValue(subplan.getInputs().get(0).getValue()); |
| return true; |
| } else { |
| AbstractLogicalOperator botOp = rootOp; |
| if (botOp.getInputs().size() != 1) { |
| return false; |
| } |
| do { |
| Mutable<ILogicalOperator> botRef = botOp.getInputs().get(0); |
| botOp = (AbstractLogicalOperator) botRef.getValue(); |
| if (botOp.getOperatorTag() == LogicalOperatorTag.EMPTYTUPLESOURCE) { |
| botRef.setValue(subplan.getInputs().get(0).getValue()); |
| opRef.setValue(rootOp); |
| return true; |
| } |
| } while (botOp.getInputs().size() == 1); |
| return false; |
| } |
| } |
| |
| private void elimSubplanOverEts(Mutable<ILogicalOperator> opRef, IOptimizationContext ctx) |
| throws AlgebricksException { |
| SubplanOperator subplan = (SubplanOperator) opRef.getValue(); |
| for (ILogicalPlan p : subplan.getNestedPlans()) { |
| for (Mutable<ILogicalOperator> r : p.getRoots()) { |
| OperatorManipulationUtil.ntsToEts(r, ctx); |
| } |
| } |
| LinkedList<Mutable<ILogicalOperator>> allRoots = subplan.allRootsInReverseOrder(); |
| if (allRoots.size() == 1) { |
| opRef.setValue(allRoots.get(0).getValue()); |
| } else { |
| ILogicalOperator topOp = null; |
| for (Mutable<ILogicalOperator> r : allRoots) { |
| if (topOp == null) { |
| topOp = r.getValue(); |
| } else { |
| LeftOuterJoinOperator j = new LeftOuterJoinOperator(new MutableObject<ILogicalExpression>( |
| ConstantExpression.TRUE)); |
| j.getInputs().add(new MutableObject<ILogicalOperator>(topOp)); |
| j.getInputs().add(r); |
| ctx.setOutputTypeEnvironment(j, j.computeOutputTypeEnvironment(ctx)); |
| topOp = j; |
| } |
| } |
| opRef.setValue(topOp); |
| } |
| } |
| } |