/**
* 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.hadoop.hive.ql.optimizer.calcite.rules;
import org.apache.calcite.plan.RelOptRule;
import org.apache.calcite.plan.RelOptRuleCall;
import org.apache.calcite.plan.RelOptRuleOperand;
import org.apache.calcite.rel.metadata.RelMetadataQuery;
import org.apache.calcite.rex.RexLiteral;
import org.apache.hadoop.hive.ql.optimizer.calcite.reloperators.HiveSortLimit;
/**
* Planner rule that removes
* a {@link org.apache.hadoop.hive.ql.optimizer.calcite.reloperators.HiveSortLimit}.
*/
public class HiveSortRemoveRule extends RelOptRule {
protected final float reductionProportion;
protected final float reductionTuples;
//~ Constructors -----------------------------------------------------------
public HiveSortRemoveRule(float reductionProportion, long reductionTuples) {
this(operand(HiveSortLimit.class, any()), reductionProportion, reductionTuples);
}
private HiveSortRemoveRule(RelOptRuleOperand operand, float reductionProportion,
long reductionTuples) {
super(operand);
this.reductionProportion = reductionProportion;
this.reductionTuples = reductionTuples;
}
//~ Methods ----------------------------------------------------------------
@Override
public boolean matches(RelOptRuleCall call) {
final HiveSortLimit sortLimit = call.rel(0);
// If it is not created by HiveSortJoinReduceRule, we cannot remove it
if (!sortLimit.isRuleCreated()) {
return false;
}
// Finally, if we do not reduce the size input enough, we bail out
int limit = RexLiteral.intValue(sortLimit.fetch);
Double rowCount = RelMetadataQuery.instance().getRowCount(sortLimit.getInput());
if (rowCount != null && limit <= reductionProportion * rowCount &&
rowCount - limit >= reductionTuples) {
return false;
}
return true;
}
@Override
public void onMatch(RelOptRuleCall call) {
final HiveSortLimit sortLimit = call.rel(0);
// We remove the limit operator
call.transformTo(sortLimit.getInput());
}
}