Fixing multiple issues reported in #497 (#524) (#527)

* Allow multiple identical sub-queries in hybrid query, removed validation for total hits


(cherry picked from commit 585fbbe)

Signed-off-by: Martin Gaievski <gaievski@amazon.com>

CHANGELOG.md

@@ -18,6 +18,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ### Bug Fixes
 - Fixed exception for case when Hybrid query being wrapped into bool query ([#490](https://github.com/opensearch-project/neural-search/pull/490))
 - Hybrid query and nested type fields ([#498](https://github.com/opensearch-project/neural-search/pull/498))
+- Fixing multiple issues reported in #497 ([#524](https://github.com/opensearch-project/neural-search/pull/524))
 ### Infrastructure
 ### Documentation
 ### Maintenance

src/main/java/org/opensearch/neuralsearch/processor/NormalizationProcessorWorkflow.java

@@ -173,8 +173,20 @@ private SearchHit[] getSearchHits(final List<Integer> docIds, final FetchSearchR
         SearchHits searchHits = fetchSearchResult.hits();
         SearchHit[] searchHitArray = searchHits.getHits();
         // validate the both collections are of the same size
-        if (Objects.isNull(searchHitArray) || searchHitArray.length != docIds.size()) {
-            throw new IllegalStateException("Score normalization processor cannot produce final query result");
+        if (Objects.isNull(searchHitArray)) {
+            throw new IllegalStateException(
+                "score normalization processor cannot produce final query result, fetch query phase returns empty results"
+            );
+        }
+        if (searchHitArray.length != docIds.size()) {
+            throw new IllegalStateException(
+                String.format(
+                    Locale.ROOT,
+                    "score normalization processor cannot produce final query result, the number of documents after fetch phase [%d] is different from number of documents from query phase [%d]",
+                    searchHitArray.length,
+                    docIds.size()
+                )
+            );
         }
         return searchHitArray;
     }

src/main/java/org/opensearch/neuralsearch/query/HybridQueryScorer.java

@@ -6,9 +6,11 @@
 package org.opensearch.neuralsearch.query;
 
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 
@@ -37,7 +39,7 @@ public final class HybridQueryScorer extends Scorer {
 
     private final float[] subScores;
 
-    private final Map<Query, Integer> queryToIndex;
+    private final Map<Query, List<Integer>> queryToIndex;
 
     public HybridQueryScorer(Weight weight, List<Scorer> subScorers) throws IOException {
         super(weight);
@@ -111,24 +113,43 @@ public float[] hybridScores() throws IOException {
         DisiWrapper topList = subScorersPQ.topList();
         for (DisiWrapper disiWrapper = topList; disiWrapper != null; disiWrapper = disiWrapper.next) {
             // check if this doc has match in the subQuery. If not, add score as 0.0 and continue
-            if (disiWrapper.scorer.docID() == DocIdSetIterator.NO_MORE_DOCS) {
+            Scorer scorer = disiWrapper.scorer;
+            if (scorer.docID() == DocIdSetIterator.NO_MORE_DOCS) {
                 continue;
             }
-            float subScore = disiWrapper.scorer.score();
-            scores[queryToIndex.get(disiWrapper.scorer.getWeight().getQuery())] = subScore;
+            Query query = scorer.getWeight().getQuery();
+            List<Integer> indexes = queryToIndex.get(query);
+            // we need to find the index of first sub-query that hasn't been set yet. Such score will have initial value of "0.0"
+            int index = indexes.stream()
+                .mapToInt(idx -> idx)
+                .filter(idx -> Float.compare(scores[idx], 0.0f) == 0)
+                .findFirst()
+                .orElseThrow(
+                    () -> new IllegalStateException(
+                        String.format(
+                            Locale.ROOT,
+                            "cannot set score for one of hybrid search subquery [%s] and document [%d]",
+                            query.toString(),
+                            scorer.docID()
+                        )
+                    )
+                );
+            scores[index] = scorer.score();
         }
         return scores;
     }
 
-    private Map<Query, Integer> mapQueryToIndex() {
-        Map<Query, Integer> queryToIndex = new HashMap<>();
+    private Map<Query, List<Integer>> mapQueryToIndex() {
+        Map<Query, List<Integer>> queryToIndex = new HashMap<>();
         int idx = 0;
         for (Scorer scorer : subScorers) {
             if (scorer == null) {
                 idx++;
                 continue;
             }
-            queryToIndex.put(scorer.getWeight().getQuery(), idx);
+            Query query = scorer.getWeight().getQuery();
+            queryToIndex.putIfAbsent(query, new ArrayList<>());
+            queryToIndex.get(query).add(idx);
             idx++;
         }
         return queryToIndex;
@@ -137,7 +158,9 @@ private Map<Query, Integer> mapQueryToIndex() {
     private DisiPriorityQueue initializeSubScorersPQ() {
         Objects.requireNonNull(queryToIndex, "should not be null");
         Objects.requireNonNull(subScorers, "should not be null");
-        DisiPriorityQueue subScorersPQ = new DisiPriorityQueue(queryToIndex.size());
+        // we need to count this way in order to include all identical sub-queries
+        int numOfSubQueries = queryToIndex.values().stream().map(List::size).reduce(0, Integer::sum);
+        DisiPriorityQueue subScorersPQ = new DisiPriorityQueue(numOfSubQueries);
         for (Scorer scorer : subScorers) {
             if (scorer == null) {
                 continue;

src/main/java/org/opensearch/neuralsearch/search/HitsThresholdChecker.java

@@ -24,9 +24,6 @@ public HitsThresholdChecker(int totalHitsThreshold) {
         if (totalHitsThreshold < 0) {
             throw new IllegalArgumentException(String.format(Locale.ROOT, "totalHitsThreshold must be >= 0, got %d", totalHitsThreshold));
         }
-        if (totalHitsThreshold == Integer.MAX_VALUE) {
-            throw new IllegalArgumentException(String.format(Locale.ROOT, "totalHitsThreshold must be less than max integer value"));
-        }
         this.totalHitsThreshold = totalHitsThreshold;
     }
 

src/test/java/org/opensearch/neuralsearch/processor/NormalizationProcessorTests.java

@@ -5,6 +5,7 @@
 
 package org.opensearch.neuralsearch.processor;
 
+import static org.hamcrest.Matchers.startsWith;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
@@ -15,6 +16,7 @@
 import static org.opensearch.neuralsearch.search.util.HybridSearchResultFormatUtil.createStartStopElementForHybridSearchResults;
 
 import java.util.List;
+import java.util.Map;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Collectors;
@@ -45,9 +47,13 @@
 import org.opensearch.neuralsearch.processor.normalization.ScoreNormalizationFactory;
 import org.opensearch.neuralsearch.processor.normalization.ScoreNormalizer;
 import org.opensearch.search.DocValueFormat;
+import org.opensearch.search.SearchHit;
+import org.opensearch.search.SearchHits;
 import org.opensearch.search.SearchShardTarget;
 import org.opensearch.search.aggregations.InternalAggregation;
 import org.opensearch.search.aggregations.pipeline.PipelineAggregator;
+import org.opensearch.search.fetch.FetchSearchResult;
+import org.opensearch.search.fetch.QueryFetchSearchResult;
 import org.opensearch.search.query.QuerySearchResult;
 import org.opensearch.test.OpenSearchTestCase;
 import org.opensearch.threadpool.TestThreadPool;
@@ -325,4 +331,172 @@ public void testNotHybridSearchResult_whenResultsNotEmptyAndNotHybridSearchResul
 
         verify(normalizationProcessorWorkflow, never()).execute(any(), any(), any(), any());
     }
+
+    public void testResultTypes_whenQueryAndFetchPresentAndSizeSame_thenCallNormalization() {
+        NormalizationProcessorWorkflow normalizationProcessorWorkflow = spy(
+            new NormalizationProcessorWorkflow(new ScoreNormalizer(), new ScoreCombiner())
+        );
+        NormalizationProcessor normalizationProcessor = new NormalizationProcessor(
+            PROCESSOR_TAG,
+            DESCRIPTION,
+            new ScoreNormalizationFactory().createNormalization(NORMALIZATION_METHOD),
+            new ScoreCombinationFactory().createCombination(COMBINATION_METHOD),
+            normalizationProcessorWorkflow
+        );
+
+        SearchRequest searchRequest = new SearchRequest(INDEX_NAME);
+        searchRequest.setBatchedReduceSize(4);
+        AtomicReference<Exception> onPartialMergeFailure = new AtomicReference<>();
+        QueryPhaseResultConsumer queryPhaseResultConsumer = new QueryPhaseResultConsumer(
+            searchRequest,
+            executor,
+            new NoopCircuitBreaker(CircuitBreaker.REQUEST),
+            searchPhaseController,
+            SearchProgressListener.NOOP,
+            writableRegistry(),
+            10,
+            e -> onPartialMergeFailure.accumulateAndGet(e, (prev, curr) -> {
+                curr.addSuppressed(prev);
+                return curr;
+            })
+        );
+        CountDownLatch partialReduceLatch = new CountDownLatch(5);
+        int shardId = 0;
+        SearchShardTarget searchShardTarget = new SearchShardTarget(
+            "node",
+            new ShardId("index", "uuid", shardId),
+            null,
+            OriginalIndices.NONE
+        );
+        QuerySearchResult querySearchResult = new QuerySearchResult();
+        TopDocs topDocs = new TopDocs(
+            new TotalHits(4, TotalHits.Relation.EQUAL_TO),
+
+            new ScoreDoc[] {
+                createStartStopElementForHybridSearchResults(4),
+                createDelimiterElementForHybridSearchResults(4),
+                new ScoreDoc(0, 0.5f),
+                new ScoreDoc(2, 0.3f),
+                new ScoreDoc(4, 0.25f),
+                new ScoreDoc(10, 0.2f),
+                createStartStopElementForHybridSearchResults(4) }
+
+        );
+        querySearchResult.topDocs(new TopDocsAndMaxScore(topDocs, 0.5f), new DocValueFormat[0]);
+        querySearchResult.setSearchShardTarget(searchShardTarget);
+        querySearchResult.setShardIndex(shardId);
+
+        FetchSearchResult fetchSearchResult = new FetchSearchResult();
+        fetchSearchResult.setShardIndex(shardId);
+        fetchSearchResult.setSearchShardTarget(searchShardTarget);
+        SearchHit[] searchHitArray = new SearchHit[] {
+            new SearchHit(4, "2", Map.of(), Map.of()),
+            new SearchHit(4, "2", Map.of(), Map.of()),
+            new SearchHit(0, "10", Map.of(), Map.of()),
+            new SearchHit(2, "1", Map.of(), Map.of()),
+            new SearchHit(4, "2", Map.of(), Map.of()),
+            new SearchHit(10, "3", Map.of(), Map.of()),
+            new SearchHit(4, "2", Map.of(), Map.of()) };
+        SearchHits searchHits = new SearchHits(searchHitArray, new TotalHits(7, TotalHits.Relation.EQUAL_TO), 10);
+        fetchSearchResult.hits(searchHits);
+
+        QueryFetchSearchResult queryFetchSearchResult = new QueryFetchSearchResult(querySearchResult, fetchSearchResult);
+        queryFetchSearchResult.setShardIndex(shardId);
+
+        queryPhaseResultConsumer.consumeResult(queryFetchSearchResult, partialReduceLatch::countDown);
+
+        SearchPhaseContext searchPhaseContext = mock(SearchPhaseContext.class);
+        normalizationProcessor.process(queryPhaseResultConsumer, searchPhaseContext);
+
+        List<QuerySearchResult> querySearchResults = queryPhaseResultConsumer.getAtomicArray()
+            .asList()
+            .stream()
+            .map(result -> result == null ? null : result.queryResult())
+            .collect(Collectors.toList());
+
+        TestUtils.assertQueryResultScores(querySearchResults);
+        verify(normalizationProcessorWorkflow).execute(any(), any(), any(), any());
+    }
+
+    public void testResultTypes_whenQueryAndFetchPresentButSizeDifferent_thenFail() {
+        NormalizationProcessorWorkflow normalizationProcessorWorkflow = spy(
+            new NormalizationProcessorWorkflow(new ScoreNormalizer(), new ScoreCombiner())
+        );
+        NormalizationProcessor normalizationProcessor = new NormalizationProcessor(
+            PROCESSOR_TAG,
+            DESCRIPTION,
+            new ScoreNormalizationFactory().createNormalization(NORMALIZATION_METHOD),
+            new ScoreCombinationFactory().createCombination(COMBINATION_METHOD),
+            normalizationProcessorWorkflow
+        );
+
+        SearchRequest searchRequest = new SearchRequest(INDEX_NAME);
+        searchRequest.setBatchedReduceSize(4);
+        AtomicReference<Exception> onPartialMergeFailure = new AtomicReference<>();
+        QueryPhaseResultConsumer queryPhaseResultConsumer = new QueryPhaseResultConsumer(
+            searchRequest,
+            executor,
+            new NoopCircuitBreaker(CircuitBreaker.REQUEST),
+            searchPhaseController,
+            SearchProgressListener.NOOP,
+            writableRegistry(),
+            10,
+            e -> onPartialMergeFailure.accumulateAndGet(e, (prev, curr) -> {
+                curr.addSuppressed(prev);
+                return curr;
+            })
+        );
+        CountDownLatch partialReduceLatch = new CountDownLatch(5);
+        int shardId = 0;
+        SearchShardTarget searchShardTarget = new SearchShardTarget(
+            "node",
+            new ShardId("index", "uuid", shardId),
+            null,
+            OriginalIndices.NONE
+        );
+        QuerySearchResult querySearchResult = new QuerySearchResult();
+        TopDocs topDocs = new TopDocs(
+            new TotalHits(4, TotalHits.Relation.EQUAL_TO),
+
+            new ScoreDoc[] {
+                createStartStopElementForHybridSearchResults(4),
+                createDelimiterElementForHybridSearchResults(4),
+                new ScoreDoc(0, 0.5f),
+                new ScoreDoc(2, 0.3f),
+                new ScoreDoc(4, 0.25f),
+                new ScoreDoc(10, 0.2f),
+                createStartStopElementForHybridSearchResults(4) }
+
+        );
+        querySearchResult.topDocs(new TopDocsAndMaxScore(topDocs, 0.5f), new DocValueFormat[0]);
+        querySearchResult.setSearchShardTarget(searchShardTarget);
+        querySearchResult.setShardIndex(shardId);
+
+        FetchSearchResult fetchSearchResult = new FetchSearchResult();
+        fetchSearchResult.setShardIndex(shardId);
+        fetchSearchResult.setSearchShardTarget(searchShardTarget);
+        SearchHit[] searchHitArray = new SearchHit[] {
+            new SearchHit(0, "10", Map.of(), Map.of()),
+            new SearchHit(2, "1", Map.of(), Map.of()),
+            new SearchHit(4, "2", Map.of(), Map.of()),
+            new SearchHit(10, "3", Map.of(), Map.of()),
+            new SearchHit(0, "10", Map.of(), Map.of()), };
+        SearchHits searchHits = new SearchHits(searchHitArray, new TotalHits(5, TotalHits.Relation.EQUAL_TO), 10);
+        fetchSearchResult.hits(searchHits);
+
+        QueryFetchSearchResult queryFetchSearchResult = new QueryFetchSearchResult(querySearchResult, fetchSearchResult);
+        queryFetchSearchResult.setShardIndex(shardId);
+
+        queryPhaseResultConsumer.consumeResult(queryFetchSearchResult, partialReduceLatch::countDown);
+
+        SearchPhaseContext searchPhaseContext = mock(SearchPhaseContext.class);
+        IllegalStateException exception = expectThrows(
+            IllegalStateException.class,
+            () -> normalizationProcessor.process(queryPhaseResultConsumer, searchPhaseContext)
+        );
+        org.hamcrest.MatcherAssert.assertThat(
+            exception.getMessage(),
+            startsWith("score normalization processor cannot produce final query result")
+        );
+    }
 }