This module supports index-time joins while searching, where joined +
This modules support index-time and query-time joins.
+ +The index-time joining support joins while searching, where joined documents are indexed as a single document block using {@link org.apache.lucene.index.IndexWriter#addDocuments}. This is useful for any normalized content (XML documents or database tables). In database terms, all rows for all joined tables matching a single row of the primary table must be @@ -34,5 +38,35 @@ org.apache.lucene.search.join.ToChildBlockJoinQuery}. This wraps any query matching parent documents, creating the joined query matching only child documents. + +
+ The query time joining is index term based and implemented as two pass search. The first pass collects all the terms from a fromField + that match the fromQuery. The second pass returns all documents that have matching terms in a toField to the terms + collected in the first pass. +
+Query time joining has the following input:
+fromField: The from field to join from.
+ fromQuery: The query executed to collect the from terms. This is usually the user specified query.
+ toField: The to field to join to
+
+ Basically the query-time joining is accessible from one static method. The user of this method supplies the method
+ with the described input and a IndexSearcher where the from terms need to be collected from. The returned
+ query can be executed with the same IndexSearcher, but also with another IndexSearcher.
+ Example usage of the {@link org.apache.lucene.search.join.JoinUtil#createJoinQuery(String, String, org.apache.lucene.search.Query, org.apache.lucene.search.IndexSearcher)} :
+
+ String fromField = "from"; // Name of the from field
+ String toField = "to"; // Name of the to field
+ Query fromQuery = new TermQuery(new Term("content", searchTerm)); // Query executed to collect from values to join to the to values
+
+ Query joinQuery = JoinUtil.createJoinQuery(fromField, toField, fromQuery, fromSearcher);
+ TopDocs topDocs = toSearcher.search(joinQuery, 10); // Note: toSearcher can be the same as the fromSearcher
+ // Render topDocs...
+
+
Index: lucene/contrib/join/src/java/org/apache/lucene/search/join/TermsQuery.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- lucene/contrib/join/src/java/org/apache/lucene/search/join/TermsQuery.java (revision )
+++ lucene/contrib/join/src/java/org/apache/lucene/search/join/TermsQuery.java (revision )
@@ -0,0 +1,168 @@
+package org.apache.lucene.search.join;
+
+/*
+ * 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.
+ */
+
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.Term;
+import org.apache.lucene.index.TermEnum;
+import org.apache.lucene.search.FilteredTermEnum;
+import org.apache.lucene.search.MultiTermQuery;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Set;
+
+/**
+ * A query that has an array of terms from a specific field. This query will match documents have one or more terms in
+ * the specified field that match with the terms specified in the array.
+ *
+ * @lucene.experimental
+ */
+class TermsQuery extends MultiTermQuery {
+
+ private static final FilteredTermEnum EMPTY = new FilteredTermEnum() {
+
+ public boolean next() throws IOException {
+ return false;
+ }
+
+ public Term term() {
+ return null;
+ }
+
+ public int docFreq() {
+ throw new IllegalStateException("this method should never be called");
+ }
+
+ public void close() throws IOException {
+ }
+
+ protected boolean termCompare(Term term) {
+ throw new IllegalStateException("this method should never be called");
+ }
+
+ public float difference() {
+ throw new IllegalStateException("this method should never be called");
+ }
+
+ protected boolean endEnum() {
+ throw new IllegalStateException("this method should never be called");
+ }
+ };
+
+ private final String[] terms;
+ private final String field;
+
+ /**
+ * @param field The field that should contain terms that are specified in the previous parameter
+ * @param terms A set terms that matching documents should have.
+ */
+ TermsQuery(String field, Set