iter

Author: pmpailis

docs/reference/search/retriever.asciidoc

@@ -523,6 +523,23 @@ You have the following options:
 ** Then set up an <<inference-example-eland,{es} service inference endpoint>> with the `rerank` task type.
 ** Refer to the <<text-similarity-reranker-retriever-example-eland,example>> on this page for a step-by-step guide.
 
+[IMPORTANT]
+====
+Scores from the re-ranking process are normalized using the following formula before returned to the user,
+to avoid having negative scores.
+[source,text]
+----
+score = max(score, 0) + min(exp(score), 1)
+----
+Using the above, any initially negative scores are projected to (0, 1) and positive scores to [1, infinity).
+To revert back if needed, one can use:
+[source, text]
+----
+score = score - 1, if score >= 0
+score = ln(score), if score < 0
+----
+====
+
 ===== Parameters
 
 `retriever`::

server/src/main/java/org/elasticsearch/search/retriever/CompoundRetrieverBuilder.java

@@ -36,7 +36,6 @@
 
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
 import java.util.Objects;

server/src/main/java/org/elasticsearch/search/retriever/rankdoc/RankDocsQuery.java

@@ -24,7 +24,6 @@
 import org.apache.lucene.search.Scorer;
 import org.apache.lucene.search.ScorerSupplier;
 import org.apache.lucene.search.Weight;
-import org.elasticsearch.index.query.RankDocsQueryBuilder;
 import org.elasticsearch.search.rank.RankDoc;
 
 import java.io.IOException;

test/framework/src/main/java/org/elasticsearch/search/rank/rerank/AbstractRerankerIT.java

@@ -56,6 +56,10 @@ public enum ThrowingRankBuilderType {
 
     protected abstract Collection<Class<? extends Plugin>> pluginsNeeded();
 
+    protected boolean shouldCheckScores() {
+        return true;
+    }
+
     @Override
     protected Collection<Class<? extends Plugin>> nodePlugins() {
         return pluginsNeeded();
@@ -95,9 +99,11 @@ public void testRerankerNoExceptions() throws Exception {
                 int rank = 1;
                 for (SearchHit searchHit : response.getHits().getHits()) {
                     assertThat(searchHit, hasId(String.valueOf(5 - (rank - 1))));
-                    assertEquals(0.5f - ((rank - 1) * 0.1f), searchHit.getScore(), 1e-5f);
                     assertThat(searchHit, hasRank(rank));
                     assertNotNull(searchHit.getFields().get(searchField));
+                    if (shouldCheckScores()) {
+                        assertEquals(0.5f - ((rank - 1) * 0.1f), searchHit.getScore(), 1e-5f);
+                    }
                     rank++;
                 }
             }
@@ -140,9 +146,11 @@ public void testRerankerPagination() throws Exception {
                 int rank = 3;
                 for (SearchHit searchHit : response.getHits().getHits()) {
                     assertThat(searchHit, hasId(String.valueOf(5 - (rank - 1))));
-                    assertEquals(0.5f - ((rank - 1) * 0.1f), searchHit.getScore(), 1e-5f);
                     assertThat(searchHit, hasRank(rank));
                     assertNotNull(searchHit.getFields().get(searchField));
+                    if (shouldCheckScores()) {
+                        assertEquals(0.5f - ((rank - 1) * 0.1f), searchHit.getScore(), 1e-5f);
+                    }
                     rank++;
                 }
             }
@@ -222,9 +230,11 @@ public void testNotAllShardsArePresentInFetchPhase() throws Exception {
                 int rank = 1;
                 for (SearchHit searchHit : response.getHits().getHits()) {
                     assertThat(searchHit, hasId(String.valueOf(5 - (rank - 1))));
-                    assertEquals(0.5f - ((rank - 1) * 0.1f), searchHit.getScore(), 1e-5f);
                     assertThat(searchHit, hasRank(rank));
                     assertNotNull(searchHit.getFields().get(searchField));
+                    if (shouldCheckScores()) {
+                        assertEquals(0.5f - ((rank - 1) * 0.1f), searchHit.getScore(), 1e-5f);
+                    }
                     rank++;
                 }
             }

x-pack/plugin/inference/qa/test-service-plugin/src/main/java/org/elasticsearch/xpack/inference/mock/AbstractTestInferenceService.java

@@ -26,9 +26,16 @@
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Random;
 
 public abstract class AbstractTestInferenceService implements InferenceService {
 
+    protected final Random random = new Random(
+        System.getProperty("tests.seed") == null
+            ? System.currentTimeMillis()
+            : Long.parseUnsignedLong(System.getProperty("tests.seed").split(":")[0], 16)
+    );
+
     protected static int stringWeight(String input, int position) {
         int hashCode = input.hashCode();
         if (hashCode < 0) {

x-pack/plugin/inference/qa/test-service-plugin/src/main/java/org/elasticsearch/xpack/inference/mock/TestRerankingServiceExtension.java

@@ -40,7 +40,6 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Random;
 
 public class TestRerankingServiceExtension implements InferenceServiceExtension {
 
@@ -151,10 +150,12 @@ public void chunkedInfer(
         private RankedDocsResults makeResults(List<String> input) {
             List<RankedDocsResults.RankedDoc> results = new ArrayList<>();
             int totalResults = input.size();
-            float minScore = new Random().nextFloat(-1f, 1f);
+            float minScore = random.nextFloat(-1f, 1f);
             float resultDiff = 0.2f;
             for (int i = 0; i < input.size(); i++) {
-                results.add(new RankedDocsResults.RankedDoc(totalResults - 1 - i, minScore + resultDiff * (totalResults - i), input.get(i)));
+                results.add(
+                    new RankedDocsResults.RankedDoc(totalResults - 1 - i, minScore + resultDiff * (totalResults - i), input.get(i))
+                );
             }
             return new RankedDocsResults(results);
         }

x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/rank/textsimilarity/TextSimilarityRankMultiNodeTests.java

@@ -50,4 +50,9 @@ public void testQueryPhaseShardThrowingAllShardsFail() throws Exception {
     public void testQueryPhaseCoordinatorThrowingAllShardsFail() throws Exception {
         // no-op
     }
+
+    @Override
+    protected boolean shouldCheckScores() {
+        return false;
+    }
 }

x-pack/plugin/inference/src/yamlRestTest/resources/rest-api-spec/test/inference/70_text_similarity_rank_retriever.yml

@@ -89,10 +89,7 @@ setup:
   - length: { hits.hits: 2 }
 
   - match: { hits.hits.0._id: "doc_2" }
-  - close_to: { hits.hits.0._score: { value: 0.4, error: 0.001 } }
-
   - match: { hits.hits.1._id: "doc_1" }
-  - close_to: { hits.hits.1._score: { value: 0.2, error: 0.001 } }
 
 ---
 "Simple text similarity rank retriever and filtering":
@@ -123,8 +120,6 @@ setup:
   - length: { hits.hits: 1 }
 
   - match: { hits.hits.0._id: "doc_1" }
-  - close_to: { hits.hits.0._score: { value: 0.2, error: 0.001 } }
-
 
 ---
 "Text similarity reranking fails if the inference ID does not exist":
@@ -211,7 +206,6 @@ setup:
   - contains: { hits.hits: { _id: "doc_2" } }
   - contains: { hits.hits: { _id: "doc_1" } }
 
-  - close_to: { hits.hits.0._explanation.value: { value: 0.4, error: 0.000001 } }
   - match: {hits.hits.0._explanation.description: "/text_similarity_reranker.match.using.inference.endpoint:.\\[my-rerank-model\\].on.document.field:.\\[text\\].*/" }
   - match: {hits.hits.0._explanation.details.0.description: "/weight.*science.*/" }