Implement rerank using muli-value fields.

Author: afoucret

x-pack/plugin/esql/qa/testFixtures/src/main/resources/rerank.csv-spec

@@ -64,26 +64,6 @@ book_no:keyword | title:text                                            | author
 5327            | War and Peace                                         | Leo Tolstoy                                 | 0.08
 ;
 
-reranker using a non text fields
-required_capability: rerank
-required_capability: match_operator_colon
-
-FROM books METADATA _score
-| WHERE title:"war and peace" AND author:"Tolstoy"
-| RERANK "war and peace" ON ratings WITH { "inference_id" : "test_reranker" }
-| EVAL _score=ROUND(_score, 2), ratings = ROUND(ratings, 2)
-| SORT _score DESC, book_no ASC
-| KEEP book_no, title, ratings, _score
-;
-
-book_no:keyword | title:text                                            | ratings:double | _score:double
-2776            | The Devil and Other Stories (Oxford World's Classics) | 5.0            | 0.33
-4536            | War and Peace (Signet Classics)                       | 4.75           | 0.25
-5327            | War and Peace                                         | 3.84           | 0.06
-9032            | War and Peace: A Novel (6 Volumes)                    | 3.81           | 0.06
-;
-
-
 reranker using a sparse input field
 required_capability: rerank
 required_capability: match_operator_colon
@@ -118,33 +98,12 @@ FROM books METADATA _score
 ;
 
 book_no:keyword | title:text                                            | author:text                                 | _score:double
-5327            | War and Peace                                         | Leo Tolstoy                                 | 0.02
-2776            | The Devil and Other Stories (Oxford World's Classics) | Leo Tolstoy                                 | 0.01
-4536            | War and Peace (Signet Classics)                       | [John Hockenberry, Leo Tolstoy, Pat Conroy] | 0.01
-9032            | War and Peace: A Novel (6 Volumes)                    | Tolstoy Leo                                 | 0.01     
-;
-
-
-reranker using multiple fields with some non text fields
-required_capability: rerank
-required_capability: match_operator_colon
-
-FROM books METADATA _score
-| WHERE title:"war and peace" AND author:"Tolstoy"
-| RERANK "war and peace" ON title, ratings WITH { "inference_id" : "test_reranker" }
-| EVAL _score=ROUND(_score, 2), ratings = ROUND(ratings, 2)
-| SORT _score DESC, book_no ASC
-| KEEP book_no, title, ratings, _score
-;
-
-book_no:keyword | title:text                                            | ratings:double | _score:double
-4536            | War and Peace (Signet Classics)                       | 4.75           | 0.02
-5327            | War and Peace                                         | 3.84           | 0.02
-2776            | The Devil and Other Stories (Oxford World's Classics) | 5.0            | 0.01
-9032            | War and Peace: A Novel (6 Volumes)                    | 3.81           | 0.01     
+4536            | War and Peace (Signet Classics)                       | [John Hockenberry, Leo Tolstoy, Pat Conroy] | 0.1
+2776            | The Devil and Other Stories (Oxford World's Classics) | Leo Tolstoy                                 | 0.09
+5327            | War and Peace                                         | Leo Tolstoy                                 | 0.09
+9032            | War and Peace: A Novel (6 Volumes)                    | Tolstoy Leo                                 | 0.09     
 ;
 
-
 reranker after a limit
 required_capability: rerank
 required_capability: match_operator_colon
@@ -263,17 +222,17 @@ FROM books METADATA _score
 | SORT _score DESC
 | LIMIT 100
 | RERANK rerank_score = "hobbit" ON description, author WITH { "inference_id" : "test_reranker" }
-| SORT rerank_score
+| SORT rerank_score DESC, book_no DESC
 | LIMIT 3
 | KEEP title, _score, rerank_score
 // end::two-queries[]
 ;
 
 // tag::two-queries-result[]
-title:text                                                       | _score:double      | rerank_score:double
-Return of the Shadow                                             | 3.4218082427978516 | 5.740527994930744E-4
-Return of the King Being the Third Part of The Lord of the Rings | 2.8398752212524414 | 9.000900317914784E-4
-The Lays of Beleriand                                            | 1.5629040002822876 | 9.36329597607255E-4
+title:text                                                                 | _score:double | rerank_score:double
+The Lord of the Rings Poster Collection: Six Paintings by Alan Lee (No. 1) | 0.7976278     | 0.125
+A Middle English Reader and Vocabulary                                     | 1.043297      | 0.07692308
+FINAL WITNESS                                                              | 1.405817      | 0.07692308
 // end::two-queries-result[]
 ;
 
@@ -286,7 +245,7 @@ FROM books METADATA _score
 | WHERE MATCH(description, "hobbit") OR MATCH(author, "Tolkien")
 | SORT _score DESC
 | LIMIT 100
-| RERANK rerank_score = "hobbit" ON description, author WITH { "inference_id" : "test_reranker" }
+| RERANK rerank_score = "hobbit" ON title, description WITH { "inference_id" : "test_reranker" }
 | EVAL original_score = _score, _score = rerank_score + original_score
 | SORT _score
 | LIMIT 3
@@ -295,10 +254,10 @@ FROM books METADATA _score
 ;
 
 // tag::combine-result[]
-title:text                                                       | _score:double      | rerank_score:double  | rerank_score:double
-Poems from the Hobbit                                            | 4.012462615966797  | 0.001396648003719747 | 0.001396648003719747
-The Lord of the Rings - Boxed Set                                | 3.768855094909668  | 0.0010020040208473802 | 0.001396648003719747
-Return of the King Being the Third Part of The Lord of the Rings | 3.6248698234558105 | 9.000900317914784E-4 | 0.001396648003719747
+title:text                                                                 | _score:double | rerank_score:double
+The Lord of the Rings Poster Collection: Six Paintings by Alan Lee (No. 1) | 0.7976278     | 0.125
+A Middle English Reader and Vocabulary                                     | 1.043297      | 0.07692308
+FINAL WITNESS                                                              | 1.405817      | 0.07692308
 // end::combine-result[]
 ;
 

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/inference/XContentRowEncoder.java

@@ -13,6 +13,8 @@
 import org.elasticsearch.xpack.esql.inference.InferenceOperator;
 import org.elasticsearch.xpack.esql.inference.InferenceService;
 
+import java.util.List;
+
 /**
  * {@link RerankOperator} is an {@link InferenceOperator} that computes relevance scores for rows using a reranking model.
  * It evaluates a row encoder expression for each input row, batches them together, and sends them to the reranking service
@@ -29,27 +31,27 @@ public class RerankOperator extends InferenceOperator {
     /**
      * Constructs a new {@code RerankOperator}.
      *
-     * @param driverContext                   The driver context.
-     * @param inferenceService                The inference service to use for executing inference requests.
-     * @param inferenceId                     The ID of the reranking model to invoke.
-     * @param queryText                       The query text to use for reranking.
-     * @param inputEvaluator                  Evaluator for computing reranked text from input rows.
-     * @param scoreChannel                    The output channel where the relevance scores will be written.
-     * @param batchSize                       The number of rows to include in each inference request batch.
+     * @param driverContext    The driver context.
+     * @param inferenceService The inference service to use for executing inference requests.
+     * @param inferenceId      The ID of the reranking model to invoke.
+     * @param queryText        The query text to use for reranking.
+     * @param inputEvaluators  Evaluator for computing reranked texts from input rows.
+     * @param scoreChannel     The output channel where the relevance scores will be written.
+     * @param batchSize        \The number of rows to include in each inference request batch.
      */
     RerankOperator(
         DriverContext driverContext,
         InferenceService inferenceService,
         String inferenceId,
         String queryText,
-        ExpressionEvaluator inputEvaluator,
+        ExpressionEvaluator[] inputEvaluators,
         int scoreChannel,
         int batchSize
     ) {
         super(
             driverContext,
             inferenceService,
-            new RerankRequestIterator.Factory(inferenceId, queryText, inputEvaluator, batchSize),
+            new RerankRequestIterator.Factory(inferenceId, queryText, inputEvaluators, batchSize),
             new RerankOutputBuilder(driverContext.blockFactory(), scoreChannel)
         );
         this.queryText = queryText;
@@ -67,10 +69,11 @@ public record Factory(
         InferenceService inferenceService,
         String inferenceId,
         String queryText,
-        ExpressionEvaluator.Factory rowEncoderFactory,
+        List<ExpressionEvaluator.Factory> inputEvaluatorFactories,
         int scoreChannel,
         int batchSize
     ) implements OperatorFactory {
+
         @Override
         public String describe() {
             return "RerankOperator[inference_id=[" + inferenceId + "], query=[" + queryText + "], score_channel=[" + scoreChannel + "]]";
@@ -83,11 +86,16 @@ public Operator get(DriverContext driverContext) {
                 inferenceService,
                 inferenceId,
                 queryText,
-                rowEncoderFactory().get(driverContext),
+                inputEvaluators(driverContext),
                 scoreChannel,
                 batchSize
             );
         }
-    }
 
+        protected ExpressionEvaluator[] inputEvaluators(DriverContext driverContext) {
+            return inputEvaluatorFactories.stream()
+                .map(evaluatorFactory -> evaluatorFactory.get(driverContext))
+                .toArray(ExpressionEvaluator[]::new);
+        }
+    }
 }