/**
* 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 java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;
import org.apache.calcite.plan.RelOptRule;
import org.apache.calcite.plan.RelOptRuleCall;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.core.Sort;
import org.apache.calcite.rel.core.Union;
import org.apache.calcite.rel.metadata.RelMetadataQuery;
import org.apache.calcite.rex.RexLiteral;
import org.apache.calcite.rex.RexNode;
import org.apache.hadoop.hive.ql.optimizer.calcite.reloperators.HiveSortLimit;
import org.apache.hadoop.hive.ql.optimizer.calcite.reloperators.HiveUnion;
/**
* Planner rule that pushes a
* {@link org.apache.hadoop.hive.ql.optimizer.calcite.reloperators.HiveSortLimit}
* past a
* {@link org.apache.hadoop.hive.ql.optimizer.calcite.reloperators.HiveUnion}.
*/
public class HiveSortUnionReduceRule extends RelOptRule {
/**
* Rule instance for Union implementation that does not preserve the ordering
* of its inputs. Thus, it makes no sense to match this rule if the Sort does
* not have a limit, i.e., {@link Sort#fetch} is null.
*/
public static final HiveSortUnionReduceRule INSTANCE = new HiveSortUnionReduceRule();
// ~ Constructors -----------------------------------------------------------
private HiveSortUnionReduceRule() {
super(
operand(
HiveSortLimit.class,
operand(HiveUnion.class, any())));
}
// ~ Methods ----------------------------------------------------------------
@Override
public boolean matches(RelOptRuleCall call) {
final HiveSortLimit sort = call.rel(0);
final HiveUnion union = call.rel(1);
// We only apply this rule if Union.all is true.
// And Sort.fetch is not null and it is more than 0.
return union.all && sort.fetch != null
// Calite bug CALCITE-987
&& RexLiteral.intValue(sort.fetch) > 0;
}
public void onMatch(RelOptRuleCall call) {
final HiveSortLimit sort = call.rel(0);
final HiveUnion union = call.rel(1);
List<RelNode> inputs = new ArrayList<>();
// Thus we use 'finishPushSortPastUnion' as a flag to identify if we have finished pushing the
// sort past a union.
boolean finishPushSortPastUnion = true;
final int offset = sort.offset == null ? 0 : RexLiteral.intValue(sort.offset);
for (RelNode input : union.getInputs()) {
// If we do not reduce the input size, we bail out
if (RexLiteral.intValue(sort.fetch) + offset < RelMetadataQuery.instance().getRowCount(input)) {
finishPushSortPastUnion = false;
// Here we do some query rewrite. We first get the new fetchRN, which is
// a sum of offset and fetch.
// We then push it through by creating a new branchSort with the new
// fetchRN but no offset.
RexNode fetchRN = sort.getCluster().getRexBuilder()
.makeExactLiteral(BigDecimal.valueOf(RexLiteral.intValue(sort.fetch) + offset));
HiveSortLimit branchSort = sort.copy(sort.getTraitSet(), input, sort.getCollation(), null,
fetchRN);
branchSort.setRuleCreated(true);
inputs.add(branchSort);
} else {
inputs.add(input);
}
}
// there is nothing to change
if (finishPushSortPastUnion) {
return;
}
// create new union and sort
HiveUnion unionCopy = (HiveUnion) union.copy(union.getTraitSet(), inputs, union.all);
HiveSortLimit result = sort.copy(sort.getTraitSet(), unionCopy, sort.getCollation(), sort.offset,
sort.fetch);
call.transformTo(result);
}
}