com.hazelcast.org.apache.calcite.rel.rules.SortRemoveRule Maven / Gradle / Ivy
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* 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,
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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.plan.RelTraitSet;
import com.hazelcast.org.apache.calcite.rel.RelCollation;
import com.hazelcast.org.apache.calcite.rel.RelCollationTraitDef;
import com.hazelcast.org.apache.calcite.rel.core.RelFactories;
import com.hazelcast.org.apache.calcite.rel.core.Sort;
import com.hazelcast.org.apache.calcite.tools.RelBuilderFactory;
/**
* Planner rule that removes
* a {@link com.hazelcast.org.apache.calcite.rel.core.Sort} if its input is already sorted.
*
* Requires {@link RelCollationTraitDef}.
*/
public class SortRemoveRule extends RelOptRule implements TransformationRule {
public static final SortRemoveRule INSTANCE =
new SortRemoveRule(RelFactories.LOGICAL_BUILDER);
/**
* Creates a SortRemoveRule.
*
* @param relBuilderFactory Builder for relational expressions
*/
public SortRemoveRule(RelBuilderFactory relBuilderFactory) {
super(operand(Sort.class, any()), relBuilderFactory, "SortRemoveRule");
}
@Override public void onMatch(RelOptRuleCall call) {
if (!call.getPlanner().getRelTraitDefs()
.contains(RelCollationTraitDef.INSTANCE)) {
// Collation is not an active trait.
return;
}
final Sort sort = call.rel(0);
if (sort.offset != null || sort.fetch != null) {
// Don't remove sort if would also remove OFFSET or LIMIT.
return;
}
// Express the "sortedness" requirement in terms of a collation trait and
// we can get rid of the sort. This allows us to use rels that just happen
// to be sorted but get the same effect.
final RelCollation collation = sort.getCollation();
assert collation == sort.getTraitSet()
.getTrait(RelCollationTraitDef.INSTANCE);
final RelTraitSet traits = sort.getInput().getTraitSet().replace(collation);
call.transformTo(convert(sort.getInput(), traits));
}
}