LUCENE-10236: Update field-weight used in CombinedFieldQuery scoring calculation (9.1.0 Backporting)

lucene/CHANGES.txt

@@ -164,6 +164,9 @@ Bug Fixes
 * LUCENE-10352: Fixed ctor argument checks: JapaneseKatakanaStemFilter,
   DoubleMetaphoneFilter (Uwe Schindler, Robert Muir)
 
+* LUCENE-10236: Stop duplicating norms when scoring in CombinedFieldQuery.
+  (Zach Chen, Jim Ferenczi, Julie Tibshirani)
+
 * LUCENE-10353: Add random null injection to TestRandomChains. (Robert Muir,
   Uwe Schindler)
 

lucene/sandbox/src/java/org/apache/lucene/sandbox/search/CombinedFieldQuery.java

@@ -418,7 +418,7 @@ public Scorer scorer(LeafReaderContext context) throws IOException {
       }
 
       MultiNormsLeafSimScorer scoringSimScorer =
-          new MultiNormsLeafSimScorer(simWeight, context.reader(), fields, true);
+          new MultiNormsLeafSimScorer(simWeight, context.reader(), fieldAndWeights.values(), true);
       LeafSimScorer nonScoringSimScorer =
           new LeafSimScorer(simWeight, context.reader(), "pseudo_field", false);
       // we use termscorers + disjunction as an impl detail

lucene/sandbox/src/java/org/apache/lucene/sandbox/search/MultiNormsLeafSimScorer.java

@@ -21,8 +21,10 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Objects;
+import java.util.Set;
 import org.apache.lucene.index.LeafReader;
 import org.apache.lucene.index.NumericDocValues;
 import org.apache.lucene.search.Explanation;
@@ -61,7 +63,13 @@ final class MultiNormsLeafSimScorer {
     if (needsScores) {
       final List<NumericDocValues> normsList = new ArrayList<>();
       final List<Float> weightList = new ArrayList<>();
+      final Set<String> duplicateCheckingSet = new HashSet<>();
       for (FieldAndWeight field : normFields) {
+        assert duplicateCheckingSet.add(field.field)
+            : "There is a duplicated field ["
+                + field.field
+                + "] used to construct MultiNormsLeafSimScorer";
+
         NumericDocValues norms = reader.getNormValues(field.field);
         if (norms != null) {
           normsList.add(norms);

lucene/sandbox/src/test/org/apache/lucene/sandbox/search/TestCombinedFieldQuery.java

@@ -16,6 +16,10 @@
  */
 package org.apache.lucene.sandbox.search;
 
+import static com.carrotsearch.randomizedtesting.RandomizedTest.atMost;
+import static com.carrotsearch.randomizedtesting.RandomizedTest.randomBoolean;
+import static com.carrotsearch.randomizedtesting.RandomizedTest.randomIntBetween;
+
 import com.carrotsearch.randomizedtesting.generators.RandomPicks;
 import java.io.IOException;
 import java.util.Arrays;
@@ -165,6 +169,80 @@ public void testSameScore() throws IOException {
     dir.close();
   }
 
+  public void testScoringWithMultipleFieldTermsMatch() throws IOException {
+    int numMatchDoc = randomIntBetween(100, 500);
+    int numHits = atMost(100);
+    int boost1 = Math.max(1, random().nextInt(5));
+    int boost2 = Math.max(1, random().nextInt(5));
+
+    Directory dir = newDirectory();
+    Similarity similarity = randomCompatibleSimilarity();
+
+    IndexWriterConfig iwc = new IndexWriterConfig();
+    iwc.setSimilarity(similarity);
+    RandomIndexWriter w = new RandomIndexWriter(random(), dir, iwc);
+
+    // adding potentially matching doc
+    for (int i = 0; i < numMatchDoc; i++) {
+      Document doc = new Document();
+
+      int freqA = random().nextInt(20) + 1;
+      for (int j = 0; j < freqA; j++) {
+        doc.add(new TextField("a", "foo", Store.NO));
+      }
+
+      freqA = random().nextInt(20) + 1;
+      if (randomBoolean()) {
+        for (int j = 0; j < freqA; j++) {
+          doc.add(new TextField("a", "foo" + j, Store.NO));
+        }
+      }
+
+      freqA = random().nextInt(20) + 1;
+      for (int j = 0; j < freqA; j++) {
+        doc.add(new TextField("a", "zoo", Store.NO));
+      }
+
+      int freqB = random().nextInt(20) + 1;
+      for (int j = 0; j < freqB; j++) {
+        doc.add(new TextField("b", "zoo", Store.NO));
+      }
+
+      freqB = random().nextInt(20) + 1;
+      if (randomBoolean()) {
+        for (int j = 0; j < freqB; j++) {
+          doc.add(new TextField("b", "zoo" + j, Store.NO));
+        }
+      }
+
+      int freqC = random().nextInt(20) + 1;
+      for (int j = 0; j < freqC; j++) {
+        doc.add(new TextField("c", "bla" + j, Store.NO));
+      }
+      w.addDocument(doc);
+    }
+
+    IndexReader reader = w.getReader();
+    IndexSearcher searcher = newSearcher(reader);
+    searcher.setSimilarity(similarity);
+
+    CombinedFieldQuery query =
+        new CombinedFieldQuery.Builder()
+            .addField("a", (float) boost1)
+            .addField("b", (float) boost2)
+            .addTerm(new BytesRef("foo"))
+            .addTerm(new BytesRef("zoo"))
+            .build();
+
+    TopScoreDocCollector completeCollector =
+        TopScoreDocCollector.create(numHits, null, Integer.MAX_VALUE);
+    searcher.search(query, completeCollector);
+
+    reader.close();
+    w.close();
+    dir.close();
+  }
+
   public void testNormsDisabled() throws IOException {
     Directory dir = newDirectory();
     Similarity similarity = randomCompatibleSimilarity();