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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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package org.apache.solr.search;
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import org.apache.lucene.search.IndexSearcher;
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/** The PostFilter interface provides a mechanism to further filter documents
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* after they have already gone through the main query and other filters.
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* This is appropriate for filters with a very high cost.
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* The filtering mechanism used is a {@link DelegatingCollector}
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* that allows the filter to not call the delegate for certain documents,
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* thus effectively filtering them out. This also avoids the normal
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* filter advancing mechanism which asks for the first acceptable document on
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* or after the target (which is undesirable for expensive filters).
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* This collector interface also enables better performance when an external system
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* must be consulted, since document ids may be buffered and batched into
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* a single request to the external system.
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* Implementations of this interface must also be a Query.
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* If an implementation can only support the collector method of
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* filtering through getFilterCollector, then ExtendedQuery.getCached()
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* should always return false, and ExtendedQuery.getCost() should
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* return no less than 100.
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* @see ExtendedQueryBase
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public interface PostFilter extends ExtendedQuery {
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/** Returns a DelegatingCollector to be run after the main query and all of it's filters, but before any sorting or grouping collectors */
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public DelegatingCollector getFilterCollector(IndexSearcher searcher);