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From: amansinha100 <git@git.apache.org>
To: dev@drill.apache.org
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References: <git-pr-169-drill@git.apache.org>
In-Reply-To: <git-pr-169-drill@git.apache.org>
Subject: [GitHub] drill pull request: DRILL-1457: Push Limit past through
 UnionExcha...
Content-Type: text/plain
Message-Id: <20150925155147.12A16DFE2E@git1-us-west.apache.org>
Date: Fri, 25 Sep 2015 15:51:47 +0000 (UTC)

Github user amansinha100 commented on a diff in the pull request:

    https://github.com/apache/drill/pull/169#discussion_r40444664
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/LimitUnionExchangeTransposeRule.java ---
    @@ -0,0 +1,64 @@
    +/**
    + * 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.physical;
    +
    +import org.apache.calcite.plan.RelOptRule;
    +import org.apache.calcite.plan.RelOptRuleCall;
    +import org.apache.calcite.rel.RelNode;
    +import org.apache.calcite.rex.RexLiteral;
    +import org.apache.calcite.rex.RexNode;
    +import org.apache.drill.exec.planner.logical.RelOptHelper;
    +
    +import java.math.BigDecimal;
    +
    +public class LimitUnionExchangeTransposeRule extends Prule{
    +  public static final RelOptRule INSTANCE = new LimitUnionExchangeTransposeRule();
    +
    +  private LimitUnionExchangeTransposeRule() {
    +    super(RelOptHelper.some(LimitPrel.class, RelOptHelper.any(UnionExchangePrel.class)), "LimitUnionExchangeTransposeRule");
    +  }
    +
    +  @Override
    +  public boolean matches(RelOptRuleCall call) {
    +    final LimitPrel limit = (LimitPrel) call.rel(0);
    +
    +    return !limit.isPushDown();
    +  }
    +
    +  @Override
    +  public void onMatch(RelOptRuleCall call) {
    +    final LimitPrel limit = (LimitPrel) call.rel(0);
    +    final UnionExchangePrel unionExchangePrel = (UnionExchangePrel) call.rel(1);
    +
    +    RelNode child = unionExchangePrel.getInput();
    +
    +    final int offset = limit.getOffset() != null ? Math.max(0, RexLiteral.intValue(limit.getOffset())) : 0;
    +    final int fetch = limit.getFetch() != null?  Math.max(0, RexLiteral.intValue(limit.getFetch())) : 0;
    +
    +    // child Limit uses conservative approach:  use offset 0 and fetch = parent limit offset + parent limit fetch.
    +    final RexNode childFetch = limit.getCluster().getRexBuilder().makeExactLiteral(BigDecimal.valueOf(offset + fetch));
    +
    +    // RexNode newFetch = limit.getCluster().getRexBuilder().makeLiteral()
    --- End diff --
    
    Remove this commented line...


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