| /* |
| * 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 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.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.expressions.AbstractFunctionCallExpression; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.ScalarFunctionCallExpression; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.functions.AlgebricksBuiltinFunctions; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.functions.IFunctionInfo; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator; |
| import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule; |
| |
| /** |
| * Matches the following operator pattern: |
| * (select) <-- ((assign)* <-- (select)*)+ |
| * |
| * Consolidates the selects to: |
| * (select) <-- (assign)* |
| * |
| */ |
| public class ConsolidateSelectsRule implements IAlgebraicRewriteRule { |
| |
| @Override |
| public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) { |
| return false; |
| } |
| |
| @Override |
| public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException { |
| AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue(); |
| if (op.getOperatorTag() != LogicalOperatorTag.SELECT) { |
| return false; |
| } |
| SelectOperator firstSelect = (SelectOperator) op; |
| |
| IFunctionInfo andFn = context.getMetadataProvider().lookupFunction(AlgebricksBuiltinFunctions.AND); |
| // New conjuncts for consolidated select. |
| AbstractFunctionCallExpression conj = null; |
| AbstractLogicalOperator topMostOp = null; |
| AbstractLogicalOperator selectParent = null; |
| AbstractLogicalOperator nextSelect = firstSelect; |
| do { |
| // Skip through assigns. |
| do { |
| selectParent = nextSelect; |
| nextSelect = (AbstractLogicalOperator) selectParent.getInputs().get(0).getValue(); |
| } while (nextSelect.getOperatorTag() == LogicalOperatorTag.ASSIGN); |
| // Stop if the child op is not a select. |
| if (nextSelect.getOperatorTag() != LogicalOperatorTag.SELECT) { |
| break; |
| } |
| // Remember the top-most op that we are not removing. |
| topMostOp = selectParent; |
| |
| // Initialize the new conjuncts, if necessary. |
| if (conj == null) { |
| conj = new ScalarFunctionCallExpression(andFn); |
| // Add the first select's condition. |
| conj.getArguments().add(new MutableObject<ILogicalExpression>(firstSelect.getCondition().getValue())); |
| } |
| |
| // Consolidate all following selects. |
| do { |
| // Add the condition nextSelect to the new list of conjuncts. |
| conj.getArguments().add(((SelectOperator) nextSelect).getCondition()); |
| selectParent = nextSelect; |
| nextSelect = (AbstractLogicalOperator) nextSelect.getInputs().get(0).getValue(); |
| } while (nextSelect.getOperatorTag() == LogicalOperatorTag.SELECT); |
| |
| // Hook up the input of the top-most remaining op if necessary. |
| if (topMostOp.getOperatorTag() == LogicalOperatorTag.ASSIGN || topMostOp == firstSelect) { |
| topMostOp.getInputs().set(0, selectParent.getInputs().get(0)); |
| } |
| |
| // Prepare for next iteration. |
| nextSelect = selectParent; |
| } while (true); |
| |
| // Did we consolidate any selects? |
| if (conj == null) { |
| return false; |
| } |
| |
| // Set the new conjuncts. |
| firstSelect.getCondition().setValue(conj); |
| context.computeAndSetTypeEnvironmentForOperator(firstSelect); |
| return true; |
| } |
| } |