| package edu.uci.ics.asterix.optimizer.rules; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| 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.LogicalExpressionTag; |
| 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.expressions.VariableReferenceExpression; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DistinctOperator; |
| import edu.uci.ics.hyracks.algebricks.rewriter.rules.AbstractExtractExprRule; |
| |
| /** |
| * Needed only bc. current Hyracks operators require keys to be fields. |
| */ |
| public class ExtractDistinctByExpressionsRule extends AbstractExtractExprRule { |
| |
| @Override |
| public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) { |
| return false; |
| } |
| |
| @Override |
| public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException { |
| AbstractLogicalOperator op1 = (AbstractLogicalOperator) opRef.getValue(); |
| if (op1.getOperatorTag() != LogicalOperatorTag.DISTINCT) { |
| return false; |
| } |
| |
| if (context.checkIfInDontApplySet(this, op1)) { |
| return false; |
| } |
| context.addToDontApplySet(this, op1); |
| DistinctOperator d = (DistinctOperator) op1; |
| boolean changed = false; |
| Mutable<ILogicalOperator> opRef2 = d.getInputs().get(0); |
| List<Mutable<ILogicalExpression>> newExprList = new ArrayList<Mutable<ILogicalExpression>>(); |
| for (Mutable<ILogicalExpression> expr : d.getExpressions()) { |
| LogicalExpressionTag tag = expr.getValue().getExpressionTag(); |
| if (tag == LogicalExpressionTag.VARIABLE || tag == LogicalExpressionTag.CONSTANT) { |
| newExprList.add(expr); |
| continue; |
| } |
| LogicalVariable v = extractExprIntoAssignOpRef(expr.getValue(), opRef2, context); |
| ILogicalExpression newExpr = new VariableReferenceExpression(v); |
| newExprList.add(new MutableObject<ILogicalExpression>(newExpr)); |
| changed = true; |
| } |
| if (changed) { |
| d.getExpressions().clear(); |
| d.getExpressions().addAll(newExprList); |
| context.computeAndSetTypeEnvironmentForOperator(d); |
| } |
| return changed; |
| } |
| |
| } |