Enhancing Elasticsearch vector store implementation

pom.xml

@@ -157,6 +157,7 @@
 		<pgvector.version>0.1.4</pgvector.version>
 		<sap.hanadb.version>2.20.11</sap.hanadb.version>
 		<postgresql.version>42.7.2</postgresql.version>
+		<elasticsearch-java.version>8.13.3</elasticsearch-java.version>
 		<milvus.version>2.3.4</milvus.version>
 		<pinecone.version>0.8.0</pinecone.version>
 		<fastjson.version>2.0.46</fastjson.version>

spring-ai-docs/src/main/antora/modules/ROOT/pages/api/vectordbs/elasticsearch.adoc

@@ -134,11 +134,18 @@ Properties starting with the `spring.ai.vectorstore.elasticsearch.*` prefix are
 
 |`spring.ai.vectorstore.elasticsearch.index-name` | The name of the index to store the vectors. | spring-ai-document-index
 |`spring.ai.vectorstore.elasticsearch.dimensions` | The number of dimensions in the vector. | 1536
-|`spring.ai.vectorstore.elasticsearch.dense-vector-indexing` | Whether to use dense vector indexing. | true
 |`spring.ai.vectorstore.elasticsearch.similarity` | The similarity function to use. | `cosine`
 |`spring.ai.vectorstore.elasticsearch.initialize-schema`| whether to initialize the required schema  | `false`
 |===
 
+The following similarity functions are available:
+
+* cosine
+* l2_norm
+* dot_product
+
+More details about each in the https://www.elastic.co/guide/en/elasticsearch/reference/master/dense-vector.html#dense-vector-params[Elasticsearch Documentation] on dense vectors.
+
 == Metadata Filtering
 
 You can leverage the generic, portable xref:api/vectordbs.adoc#metadata-filters[metadata filters] with Elasticsearch as well.
@@ -214,10 +221,11 @@ Read the link:https://www.elastic.co/guide/en/elasticsearch/client/java-api-clie
 ----
 @Bean
 public RestClient restClient() {
-    RestClientBuilder builder = RestClient.builder(new HttpHost("<host>", 9200, "http"));
-    Header[] defaultHeaders = new Header[] { new BasicHeader("Authorization", "Basic <encoded username and password>") };
-    builder.setDefaultHeaders(defaultHeaders);
-    return builder.build();
+    RestClient.builder(new HttpHost("<host>", 9200, "http"))
+        .setDefaultHeaders(new Header[]{
+            new BasicHeader("Authorization", "Basic <encoded username and password>")
+        })
+        .build();
 }
 ----
 

spring-ai-spring-boot-autoconfigure/pom.xml

@@ -260,6 +260,7 @@
 			<optional>true</optional>
 		</dependency>
 
+		<!-- Elasticsearch Vector Store-->
 		<dependency>
 			<groupId>org.springframework.ai</groupId>
 			<artifactId>spring-ai-elasticsearch-store</artifactId>
@@ -281,6 +282,12 @@
 			<optional>true</optional>
 		</dependency>
 
+		<dependency>
+			<groupId>co.elastic.clients</groupId>
+			<artifactId>elasticsearch-java</artifactId>
+			<version>${elasticsearch-java.version}</version>
+		</dependency>
+
 		<!-- test dependencies -->
 
 		<dependency>

spring-ai-spring-boot-autoconfigure/src/main/java/org/springframework/ai/autoconfigure/vectorstore/elasticsearch/ElasticsearchVectorStoreAutoConfiguration.java

@@ -52,10 +52,7 @@ ElasticsearchVectorStore vectorStore(ElasticsearchVectorStoreProperties properti
 		if (properties.getDimensions() != null) {
 			elasticsearchVectorStoreOptions.setDimensions(properties.getDimensions());
 		}
-		if (properties.isDenseVectorIndexing() != null) {
-			elasticsearchVectorStoreOptions.setDenseVectorIndexing(properties.isDenseVectorIndexing());
-		}
-		if (StringUtils.hasText(properties.getSimilarity())) {
+		if (properties.getSimilarity() != null) {
 			elasticsearchVectorStoreOptions.setSimilarity(properties.getSimilarity());
 		}
 

spring-ai-spring-boot-autoconfigure/src/main/java/org/springframework/ai/autoconfigure/vectorstore/elasticsearch/ElasticsearchVectorStoreProperties.java

@@ -16,6 +16,7 @@
 package org.springframework.ai.autoconfigure.vectorstore.elasticsearch;
 
 import org.springframework.ai.autoconfigure.CommonVectorStoreProperties;
+import org.springframework.ai.vectorstore.SimilarityFunction;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
 /**
@@ -37,15 +38,10 @@ public class ElasticsearchVectorStoreProperties extends CommonVectorStorePropert
 	 */
 	private Integer dimensions;
 
-	/**
-	 * Whether to use dense vector indexing.
-	 */
-	private Boolean denseVectorIndexing;
-
 	/**
 	 * The similarity function to use.
 	 */
-	private String similarity;
+	private SimilarityFunction similarity;
 
 	public String getIndexName() {
 		return this.indexName;
@@ -63,19 +59,11 @@ public void setDimensions(Integer dimensions) {
 		this.dimensions = dimensions;
 	}
 
-	public Boolean isDenseVectorIndexing() {
-		return denseVectorIndexing;
-	}
-
-	public void setDenseVectorIndexing(Boolean denseVectorIndexing) {
-		this.denseVectorIndexing = denseVectorIndexing;
-	}
-
-	public String getSimilarity() {
+	public SimilarityFunction getSimilarity() {
 		return similarity;
 	}
 
-	public void setSimilarity(String similarity) {
+	public void setSimilarity(SimilarityFunction similarity) {
 		this.similarity = similarity;
 	}
 

spring-ai-spring-boot-autoconfigure/src/test/java/org/springframework/ai/autoconfigure/vectorstore/elasticsearch/ElasticsearchVectorStoreAutoConfigurationIT.java

@@ -18,13 +18,12 @@
 import org.awaitility.Awaitility;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.condition.EnabledIfEnvironmentVariable;
-import org.junit.jupiter.params.ParameterizedTest;
-import org.junit.jupiter.params.provider.ValueSource;
 import org.springframework.ai.autoconfigure.openai.OpenAiAutoConfiguration;
 import org.springframework.ai.autoconfigure.retry.SpringAiRetryAutoConfiguration;
 import org.springframework.ai.document.Document;
 import org.springframework.ai.vectorstore.ElasticsearchVectorStore;
 import org.springframework.ai.vectorstore.SearchRequest;
+import org.springframework.ai.vectorstore.SimilarityFunction;
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchRestClientAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration;
@@ -51,8 +50,6 @@ class ElasticsearchVectorStoreAutoConfigurationIT {
 			"docker.elastic.co/elasticsearch/elasticsearch:8.12.2")
 		.withEnv("xpack.security.enabled", "false");
 
-	private static final String DEFAULT = "default cosine similarity";
-
 	private List<Document> documents = List.of(
 			new Document("1", getText("classpath:/test/data/spring.ai.txt"), Map.of("meta1", "meta1")),
 			new Document("2", getText("classpath:/test/data/time.shelter.txt"), Map.of()),
@@ -65,21 +62,14 @@ class ElasticsearchVectorStoreAutoConfigurationIT {
 		.withPropertyValues("spring.elasticsearch.uris=" + elasticsearchContainer.getHttpHostAddress(),
 				"spring.ai.openai.api-key=" + System.getenv("OPENAI_API_KEY"));
 
-	@ParameterizedTest(name = "{0} : {displayName} ")
-	@ValueSource(strings = { DEFAULT, """
-			  double value = dotProduct(params.query_vector, 'embedding');
-			  return sigmoid(1, Math.E, -value);
-			""", "1 / (1 + l1norm(params.query_vector, 'embedding'))",
-			"1 / (1 + l2norm(params.query_vector, 'embedding'))" })
-	public void addAndSearchTest(String similarityFunction) {
+	// No parametrized test based on similarity function,
+	// by default the bean will be created using cosine.
+	@Test
+	public void addAndSearchTest() {
 
 		this.contextRunner.run(context -> {
 			ElasticsearchVectorStore vectorStore = context.getBean(ElasticsearchVectorStore.class);
 
-			if (!DEFAULT.equals(similarityFunction)) {
-				vectorStore.withSimilarityFunction(similarityFunction);
-			}
-
 			vectorStore.add(documents);
 
 			Awaitility.await()
@@ -120,16 +110,15 @@ public void propertiesTest() {
 					"spring.ai.vectorstore.elasticsearch.index-name=example",
 					"spring.ai.vectorstore.elasticsearch.dimensions=1024",
 					"spring.ai.vectorstore.elasticsearch.dense-vector-indexing=true",
-					"spring.ai.vectorstore.elasticsearch.similarity=dot_product")
+					"spring.ai.vectorstore.elasticsearch.similarity=cosine")
 			.run(context -> {
 				var properties = context.getBean(ElasticsearchVectorStoreProperties.class);
 				var elasticsearchVectorStore = context.getBean(ElasticsearchVectorStore.class);
 
 				assertThat(properties).isNotNull();
 				assertThat(properties.getIndexName()).isEqualTo("example");
 				assertThat(properties.getDimensions()).isEqualTo(1024);
-				assertThat(properties.isDenseVectorIndexing()).isTrue();
-				assertThat(properties.getSimilarity()).isEqualTo("dot_product");
+				assertThat(properties.getSimilarity()).isEqualTo(SimilarityFunction.cosine);
 
 				assertThat(elasticsearchVectorStore).isNotNull();
 			});

vector-stores/spring-ai-elasticsearch-store/pom.xml

@@ -35,6 +35,7 @@
 		<dependency>
 			<groupId>co.elastic.clients</groupId>
 			<artifactId>elasticsearch-java</artifactId>
+			<version>${elasticsearch-java.version}</version>
 		</dependency>
 
 		<!-- TESTING -->
@@ -45,7 +46,6 @@
 			<scope>test</scope>
 		</dependency>
 
-
 		<dependency>
 			<groupId>org.springframework.ai</groupId>
 			<artifactId>spring-ai-test</artifactId>