com.hazelcast.org.apache.calcite.rel.hint.HintPredicate Maven / Gradle / Ivy
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* 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.
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* limitations under the License.
*/
package com.hazelcast.org.apache.calcite.rel.hint;
import com.hazelcast.org.apache.calcite.rel.RelNode;
/**
* A {@code HintPredicate} indicates whether a {@link com.hazelcast.org.apache.calcite.rel.RelNode}
* can apply the specified hint.
*
* Every supported hint should register a {@code HintPredicate}
* into the {@link HintStrategyTable}. For example, {@link HintPredicates#JOIN} implies
* that this hint would be propagated and applied to the {@link com.hazelcast.org.apache.calcite.rel.core.Join}
* relational expressions.
*
*
Usually use {@link NodeTypeHintPredicate} is enough for most of the {@link RelHint}s.
* Some of the hints can only be matched to the relational expression with special
* match conditions(not only the relational expression type).
* i.e. "hash_join(r, st)", this hint can only be applied to JOIN expression that
* has "r" and "st" as the input table names. To implement this, you can make a custom
* {@code HintPredicate} instance.
*
*
A {@code HintPredicate} can be used independently or cascaded with other strategies
* with method {@link HintPredicates#and}.
*
*
In {@link HintStrategyTable} the predicate is used for
* hints registration.
*
* @see HintStrategyTable
*/
public interface HintPredicate {
/**
* Decides if the given {@code hint} can be applied to
* the relational expression {@code rel}.
*
* @param hint The hint
* @param rel The relational expression
* @return True if the {@code hint} can be applied to the {@code rel}
*/
boolean apply(RelHint hint, RelNode rel);
}