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/*
* 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 com.hazelcast.com.liance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.com.hazelcast.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 com.hazelcast.org.apache.calcite.rel.rules;
import com.hazelcast.org.apache.calcite.plan.RelOptRule;
import com.hazelcast.org.apache.calcite.plan.RelOptRuleCall;
import com.hazelcast.org.apache.calcite.rel.RelNode;
import com.hazelcast.org.apache.calcite.rel.core.RelFactories;
import com.hazelcast.org.apache.calcite.rel.core.Sort;
import com.hazelcast.org.apache.calcite.rel.core.Union;
import com.hazelcast.org.apache.calcite.rel.metadata.RelMdUtil;
import com.hazelcast.org.apache.calcite.rel.metadata.RelMetadataQuery;
import com.hazelcast.org.apache.calcite.tools.RelBuilderFactory;
import java.util.ArrayList;
import java.util.List;
/**
* Planner rule that pushes a {@link com.hazelcast.org.apache.calcite.rel.core.Sort} past a
* {@link com.hazelcast.org.apache.calcite.rel.core.Union}.
*
*/
public class SortUnionTransposeRule extends RelOptRule implements TransformationRule {
/** 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 SortUnionTransposeRule INSTANCE = new SortUnionTransposeRule(false);
/** Rule instance for Union implementation that preserves the ordering
* of its inputs. It is still worth applying this rule even if the Sort
* does not have a limit, for the merge of already sorted inputs that
* the Union can do is usually cheap. */
public static final SortUnionTransposeRule MATCH_NULL_FETCH = new SortUnionTransposeRule(true);
/** Whether to match a Sort whose {@link Sort#fetch} is null. Generally
* this only makes sense if the Union preserves order (and merges). */
private final boolean matchNullFetch;
// ~ Constructors -----------------------------------------------------------
private SortUnionTransposeRule(boolean matchNullFetch) {
this(Sort.class, Union.class, matchNullFetch, RelFactories.LOGICAL_BUILDER,
"SortUnionTransposeRule:default");
}
/**
* Creates a SortUnionTransposeRule.
*/
public SortUnionTransposeRule(
Class sortClass,
Class unionClass,
boolean matchNullFetch,
RelBuilderFactory relBuilderFactory,
String description) {
super(
operand(sortClass,
operand(unionClass, any())),
relBuilderFactory, description);
this.matchNullFetch = matchNullFetch;
}
// ~ Methods ----------------------------------------------------------------
@Override public boolean matches(RelOptRuleCall call) {
final Sort sort = call.rel(0);
final Union union = call.rel(1);
// We only apply this rule if Union.all is true and Sort.offset is null.
// There is a flag indicating if this rule should be applied when
// Sort.fetch is null.
return union.all
&& sort.offset == null
&& (matchNullFetch || sort.fetch != null);
}
public void onMatch(RelOptRuleCall call) {
final Sort sort = call.rel(0);
final Union union = call.rel(1);
List inputs = new ArrayList<>();
// Thus we use 'ret' as a flag to identify if we have finished pushing the
// sort past a union.
boolean ret = true;
final RelMetadataQuery mq = call.getMetadataQuery();
for (RelNode input : union.getInputs()) {
if (!RelMdUtil.checkInputForCollationAndLimit(mq, input,
sort.getCollation(), sort.offset, sort.fetch)) {
ret = false;
Sort branchSort = sort.copy(sort.getTraitSet(), input,
sort.getCollation(), sort.offset, sort.fetch);
inputs.add(branchSort);
} else {
inputs.add(input);
}
}
// there is nothing to change
if (ret) {
return;
}
// create new union and sort
Union unionCopy = (Union) union
.copy(union.getTraitSet(), inputs, union.all);
Sort result = sort.copy(sort.getTraitSet(), unionCopy, sort.getCollation(),
sort.offset, sort.fetch);
call.transformTo(result);
}
}