/**
* 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.tajo.engine.planner.rewrite;
import org.apache.tajo.engine.planner.LogicalPlan;
import org.apache.tajo.engine.planner.PlanningException;
/**
* An interface for a rewrite rule.
*/
public interface RewriteRule {
/**
* It returns the rewrite rule name. It will be used for debugging and
* building a optimization history.
*
* @return The rewrite rule name
*/
String getName();
/**
* This method checks if this rewrite rule can be applied to a given query plan.
* For example, the selection push down can not be applied to the query plan without any filter.
* In such case, it will return false.
*
* @param plan The plan to be checked
* @return True if this rule can be applied to a given plan. Otherwise, false.
*/
boolean isEligible(LogicalPlan plan);
/**
* Updates a logical plan and returns an updated logical plan rewritten by this rule.
* It must be guaranteed that the input logical plan is not modified even after rewrite.
* In other words, the rewrite has to modify an plan copied from the input plan.
*
* @param plan Input logical plan. It will not be modified.
* @return The rewritten logical plan.
*/
LogicalPlan rewrite(LogicalPlan plan) throws PlanningException;
}