/**
* 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.logical;
import org.eigenbase.rel.RelNode;
import org.eigenbase.rel.SortRel;
import org.eigenbase.relopt.Convention;
import org.eigenbase.relopt.RelOptRule;
import org.eigenbase.relopt.RelOptRuleCall;
import org.eigenbase.relopt.RelTraitSet;
/**
* This rule converts a SortRel that has either a offset and fetch into a Drill Sort and Limit Rel
*/
public class DrillLimitRule extends RelOptRule {
public static DrillLimitRule INSTANCE = new DrillLimitRule();
private DrillLimitRule() {
super(RelOptHelper.any(SortRel.class, Convention.NONE), "DrillLimitRule");
}
@Override
public boolean matches(RelOptRuleCall call) {
final SortRel sort = call.rel(0);
return sort.offset != null || sort.fetch != null;
}
@Override
public void onMatch(RelOptRuleCall call) {
final SortRel incomingSort = call.rel(0);
final RelTraitSet incomingTraits = incomingSort.getTraitSet();
RelNode input = incomingSort.getChild();
// if the Optiq sort rel includes a collation and a limit, we need to create a copy the sort rel that excludes the
// limit information.
if (!incomingSort.getCollation().getFieldCollations().isEmpty()) {
input = incomingSort.copy(incomingTraits, input, incomingSort.getCollation(), null, null);
}
RelNode convertedInput = convert(input, input.getTraitSet().plus(DrillRel.DRILL_LOGICAL));
call.transformTo(new DrillLimitRel(incomingSort.getCluster(), convertedInput.getTraitSet().plus(DrillRel.DRILL_LOGICAL), convertedInput, incomingSort.offset, incomingSort.fetch));
}
}