Skip setting vector search limit if unlimited.

Skip setting limit if unlimited and rely on server side command validation.

Closes: #4963

Author: christophstrobl

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/VectorSearchOperation.java

@@ -236,7 +236,10 @@ public Document toDocument(AggregationOperationContext context) {
 		}
 
 		$vectorSearch.append("index", indexName);
-		$vectorSearch.append("limit", limit.max());
+
+		if(limit.isLimited()) {
+			$vectorSearch.append("limit", limit.max());
+		}
 
 		if (numCandidates != null) {
 			$vectorSearch.append("numCandidates", numCandidates);

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/VectorSearchOperationUnitTests.java

@@ -15,14 +15,14 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import static org.assertj.core.api.Assertions.*;
+import static org.springframework.data.mongodb.test.util.Assertions.assertThat;
 
 import java.util.List;
 
 import org.bson.Document;
 import org.junit.jupiter.api.Test;
-
 import org.springframework.data.annotation.Id;
+import org.springframework.data.domain.Limit;
 import org.springframework.data.mongodb.core.aggregation.VectorSearchOperation.SearchType;
 import org.springframework.data.mongodb.core.mapping.Field;
 import org.springframework.data.mongodb.core.query.Criteria;
@@ -103,6 +103,16 @@ void mapsCriteriaToDomainType() {
 				.containsExactly(new Document("$vectorSearch", new Document($VECTOR_SEARCH).append("filter", filter)));
 	}
 
+	@Test // GH-4963
+	void shouldSkipLimitIfUnlimited() {
+
+		VectorSearchOperation $search = VectorSearchOperation.search("vector_index").path("plot_embedding")
+				.vector(-0.0016261312, -0.028070757, -0.011342932).limit(Limit.unlimited());
+
+		List<Document> stages = $search.toPipelineStages(TestAggregationContext.contextFor(Movie.class));
+		assertThat(stages.get(0)).doesNotContainKey("$vectorSearch.limit");
+	}
+
 	static class Movie {
 
 		@Id String id;