com.hazelcast.org.apache.calcite.rel.rules.UnionEliminatorRule Maven / Gradle / Ivy
/*
* 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.core.RelFactories;
import com.hazelcast.org.apache.calcite.rel.core.Union;
import com.hazelcast.org.apache.calcite.rel.logical.LogicalUnion;
import com.hazelcast.org.apache.calcite.tools.RelBuilderFactory;
/**
* UnionEliminatorRule
checks to see if its possible to optimize a
* Union call by eliminating the Union operator altogether in the case the call
* consists of only one input.
*/
public class UnionEliminatorRule extends RelOptRule
implements SubstitutionRule {
public static final UnionEliminatorRule INSTANCE =
new UnionEliminatorRule(LogicalUnion.class, RelFactories.LOGICAL_BUILDER);
//~ Constructors -----------------------------------------------------------
/**
* Creates a UnionEliminatorRule.
*/
public UnionEliminatorRule(Class clazz,
RelBuilderFactory relBuilderFactory) {
super(operand(clazz, any()), relBuilderFactory, null);
}
//~ Methods ----------------------------------------------------------------
@Override public boolean matches(RelOptRuleCall call) {
Union union = call.rel(0);
return union.all && union.getInputs().size() == 1;
}
public void onMatch(RelOptRuleCall call) {
Union union = call.rel(0);
call.transformTo(union.getInputs().get(0));
}
@Override public boolean autoPruneOld() {
return true;
}
}