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Subject [GitHub] [lucene-solr] jtibshirani commented on a change in pull request #715: LUCENE-7714 Add a range query that takes advantage of index sorting.
Date Wed, 12 Jun 2019 20:04:02 GMT
jtibshirani commented on a change in pull request #715: LUCENE-7714 Add a range query that
takes advantage of index sorting.
URL: https://github.com/apache/lucene-solr/pull/715#discussion_r293093539
 
 

 ##########
 File path: lucene/core/src/java/org/apache/lucene/document/IndexSortDocValuesRangeQuery.java
 ##########
 @@ -0,0 +1,279 @@
+/*
+ * 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.lucene.document;
+
+import java.io.IOException;
+import java.util.Objects;
+
+import org.apache.lucene.index.DocValues;
+import org.apache.lucene.index.LeafReader;
+import org.apache.lucene.index.LeafReaderContext;
+import org.apache.lucene.index.NumericDocValues;
+import org.apache.lucene.index.SortedNumericDocValues;
+import org.apache.lucene.search.BooleanClause;
+import org.apache.lucene.search.ConstantScoreScorer;
+import org.apache.lucene.search.ConstantScoreWeight;
+import org.apache.lucene.search.DocIdSetIterator;
+import org.apache.lucene.search.FieldComparator;
+import org.apache.lucene.search.IndexSearcher;
+import org.apache.lucene.search.LeafFieldComparator;
+import org.apache.lucene.search.Query;
+import org.apache.lucene.search.QueryVisitor;
+import org.apache.lucene.search.ScoreMode;
+import org.apache.lucene.search.Scorer;
+import org.apache.lucene.search.Sort;
+import org.apache.lucene.search.SortField;
+import org.apache.lucene.search.Weight;
+
+/**
+ * A range query that takes advantage of the fact that the index is sorted to speed up execution.
+ * It assumes that the index is sorted on the same field as the query, and performs binary
search
+ * on the field's doc values to find the documents at the lower and upper ends of the range.
+ *
+ * This optimized execution strategy can only be used if all of these conditions hold:
+ *   - The index is sorted, and its primary sort is on the same field as the query.
+ *   - The provided field has {@link SortedNumericDocValues}.
+ *   - The segments must have at most one field value per document (otherwise we cannot easily
+ *     determine the matching document IDs through a binary search).
+ */
+public final class IndexSortDocValuesRangeQuery extends Query {
+
+  private final String field;
+  private final long lowerValue;
+  private final long upperValue;
+
+  /**
+   * Creates a new {@link IndexSortDocValuesRangeQuery}.
+   *
+   * @param field The field name.
+   * @param lowerValue The lower end of the range (inclusive).
+   * @param upperValue The upper end of the range (inclusive).
+   */
+  public IndexSortDocValuesRangeQuery(String field,
+                                      long lowerValue,
+                                      long upperValue) {
+    this.field = field;
+    this.lowerValue = lowerValue;
+    this.upperValue = upperValue;
+  }
+
+  @Override
+  public Weight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) {
+    return new ConstantScoreWeight(this, boost) {
+      @Override
+      public Scorer scorer(LeafReaderContext context) throws IOException {
+        LeafReader reader = context.reader();
+
+        Sort indexSort = reader.getMetaData().getSort();
+        if (indexSort == null || indexSort.getSort().length == 0) {
+          throw new IllegalArgumentException("To use IndexSortDocValuesRangeQuery, the index
must be sorted.");
+        }
+
+        SortField sortField = indexSort.getSort()[0];
+        if (sortField.getField().equals(field) == false) {
+          throw new IllegalArgumentException("To use IndexSortDocValuesRangeQuery, the index
must be sorted " +
+              "on the same field as the query field.");
+        }
+
+        SortedNumericDocValues sortedDocValues = reader.getSortedNumericDocValues(field);
+        NumericDocValues docValues = DocValues.unwrapSingleton(sortedDocValues);
 
 Review comment:
   When a document has multiple values, the index sort must choose one of them to decide where
it should be placed. So a binary search may miss a document where the value we’ve sorted
on is outside the range, but it also contains a value that falls within the range.

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