| /* |
| * 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.directory.server.xdbm.search; |
| |
| |
| import org.apache.directory.api.ldap.model.filter.ExprNode; |
| |
| |
| /** |
| * An optimizer applies heuristics to determine best execution path to a search |
| * filter based on scan counts within database indices. It annotates the nodes |
| * of an expression subtree by setting a "count" key in the node. Its goal is |
| * to annotate nodes with counts to indicate which nodes to iterate over thereby |
| * minimizing the number cycles in a search. The SearchEngine relies on these |
| * count markers to determine the appropriate path. |
| * |
| * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> |
| */ |
| public interface Optimizer |
| { |
| /** |
| * Annotates the expression node tree for optimized traversal metrics. |
| * |
| * @param node the root of the expression node tree |
| * @throws Exception if there are failures while optimizing |
| */ |
| Long annotate( ExprNode node ) throws Exception; |
| } |