Java: Multi-Database Support for Cluster Mode Valkey 9.0 (#4658)

* - Implement database selection for cluster clients when database_id != 0
- Send SELECT command to all cluster nodes using MultiNode routing
- Add comprehensive error handling with clear error messages
- Include test for database selection error handling in cluster mode
- Support backward compatibility with servers that don't support multi-db cluster mode
- Enable cluster-databases=16 for Valkey 9.0+ in cluster manager

This enables cluster clients to work with non-default databases on Valkey 9.0+
servers configured with cluster-databases support, while gracefully handling
older servers that don't support this feature.

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* update valkey9 multi db tests

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* fix lint

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* fixing valkey 9 cluster tests

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* add to route to all nodes in the core

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* rust lint fix

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* implement database selection in cluster mode via connection parameters

- Add database_id field to ClusterParams and BuilderParams structs
- Add database() method to ClusterClientBuilder for setting database ID
- Pass database_id through connection info instead of post-connection SELECT
- Remove SELECT command from cluster routing
- Remove post-connection SELECT command logic from create_cluster_client
- Add comprehensive tests for database isolation and reconnection behavior
- Verify database ID persistence across node reconnections
- Test multi-database cluster support with proper isolation verification

This change moves database selection from a post-connection SELECT command
to a connection parameter, which is more reliable for cluster mode and
handles reconnections automatically. The approach works with servers that
support multi-database cluster configurations (like Valkey 9.0+).

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* add valkey9 constraint in the core tests

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* fix core test not skipping test when version was lower than valkey 9

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* Fix version check

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* refactored test test_set_database_id_after_reconnection to be similar from standalone
removed is_valkey_9_or_higher

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* removed tests and cleanup

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* renamed builder.database to builder.database_id

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* Java: implement multi-database support for cluster mode

- Move databaseId from GlideClientConfiguration to BaseClientConfiguration
- Add databaseId validation and protobuf integration
- Update SELECT command with AllNodes routing and reconnection warnings
- Add connection management for database selection after auth
- Add comprehensive tests with Valkey 9+ version guards

Completes Java client implementation for Valkey 9 cluster multi-database support.

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* fixing database id restriction

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* fixed java test error select_command_invalid_database_standalone

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* fixed lint errors

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* Refactored select command to route to all nodes per default
Removed the option to provide a route

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* java lint fix

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* java: Remove SELECT command from cluster client

- Remove select() method from GlideClusterClient and ConnectionManagementClusterCommands interface
- Delete MultiDatabaseTests.java which tested SELECT command functionality
- Remove SELECT command tests from SharedCommandTests.java
- Add focused test for cluster database_id configuration in ClusterClientTests
- Remove SELECT import from GlideClusterClient

The SELECT command is being removed from the cluster client API as database
selection should be handled through client configuration (databaseId parameter)
rather than runtime commands, which provides better consistency and avoids
reconnection issues.

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* remove database_id validatation and simplified tests

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* added changelog

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* fix documentation

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

* fix databaseId documentation

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

---------

Signed-off-by: affonsov <67347924+affonsov@users.noreply.github.com>

Author: affonsov

CHANGELOG.md

@@ -6,6 +6,7 @@
 * JAVA: Valkey 9 new commands HASH items expiration ([#4556](https://github.com/valkey-io/valkey-glide/pull/4556))
 * NODE: Valkey 9 support - Add Hash Field Expiration Commands Support ([#4598](https://github.com/valkey-io/valkey-glide/pull/4598))
 * Python: Valkey 9 new hash field expiration commands ([#4610](https://github.com/valkey-io/valkey-glide/pull/4610))
+* Java: Multi-Database Support for Cluster Mode Valkey 9.0 ([#4658](https://github.com/valkey-io/valkey-glide/pull/4658))
 * Go: Add Multi-Database Support for Cluster Mode Valkey 9.0 ([#4660](https://github.com/valkey-io/valkey-glide/pull/4660))
 * Python: Add Multi-Database Support for Cluster Mode Valkey 9.0 ([#4659](https://github.com/valkey-io/valkey-glide/pull/4659))
 

java/client/src/main/java/glide/api/commands/ConnectionManagementCommands.java

@@ -110,6 +110,23 @@ public interface ConnectionManagementCommands {
     /**
      * Changes the currently selected database.
      *
+     * <p><b>WARNING:</b> This command is <b>NOT RECOMMENDED</b> for production use. Upon
+     * reconnection, the client will revert to the database_id specified in the client configuration
+     * (default: 0), NOT the database selected via this command.
+     *
+     * <p><b>RECOMMENDED APPROACH:</b> Use the database_id parameter in client configuration instead:
+     *
+     * <p><b>RECOMMENDED EXAMPLE:</b>
+     *
+     * <pre>{@code
+     * GlideClient client = GlideClient.createClient(
+     *     GlideClientConfiguration.builder()
+     *         .address(NodeAddress.builder().host("localhost").port(6379).build())
+     *         .databaseId(5)  // Recommended: persists across reconnections
+     *         .build()
+     * ).get();
+     * }</pre>
+     *
      * @see <a href="https://valkey.io/commands/select/">valkey.io</a> for details.
      * @param index The index of the database to select.
      * @return A simple <code>OK</code> response.

java/client/src/main/java/glide/api/models/configuration/BaseClientConfiguration.java

@@ -85,6 +85,12 @@ public abstract class BaseClientConfiguration {
     /** Strategy used to determine how and when to reconnect, in case of connection failures. */
     private final BackoffStrategy reconnectStrategy;
 
+    /**
+     * Index of the logical database to connect to. Must be non-negative and within the range
+     * supported by the server configuration. If not specified, defaults to database 0.
+     */
+    private final Integer databaseId;
+
     /**
      * Enables lazy connection mode, where physical connections to the server(s) are deferred until
      * the first command is sent. This can reduce startup latency and allow for client creation in

java/client/src/main/java/glide/api/models/configuration/GlideClientConfiguration.java

@@ -34,9 +34,6 @@
 @ToString
 public class GlideClientConfiguration extends BaseClientConfiguration {
 
-    /** Index of the logical database to connect to. */
-    private final Integer databaseId;
-
     /** Subscription configuration for the current client. */
     private final StandaloneSubscriptionConfiguration subscriptionConfiguration;
 

java/client/src/main/java/glide/managers/ConnectionManager.java

@@ -162,6 +162,10 @@ private ConnectionRequest.Builder setupConnectionRequestBuilderBaseConfiguration
             connectionRequestBuilder.setLazyConnect(configuration.isLazyConnect());
         }
 
+        if (configuration.getDatabaseId() != null) {
+            connectionRequestBuilder.setDatabaseId(configuration.getDatabaseId());
+        }
+
         return connectionRequestBuilder;
     }
 
@@ -176,10 +180,6 @@ private ConnectionRequest.Builder setupConnectionRequestBuilderGlideClient(
                 setupConnectionRequestBuilderBaseConfiguration(configuration);
         connectionRequestBuilder.setClusterModeEnabled(false);
 
-        if (configuration.getDatabaseId() != null) {
-            connectionRequestBuilder.setDatabaseId(configuration.getDatabaseId());
-        }
-
         if (configuration.getSubscriptionConfiguration() != null) {
             if (configuration.getProtocol() == ProtocolVersion.RESP2) {
                 throw new ConfigurationError(

java/client/src/test/java/glide/api/models/configuration/BaseClientConfigurationTest.java

@@ -0,0 +1,59 @@
+/** Copyright Valkey GLIDE Project Contributors - SPDX Identifier: Apache-2.0 */
+package glide.api.models.configuration;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+public class BaseClientConfigurationTest {
+
+    /** Test implementation of BaseClientConfiguration for testing purposes */
+    private static class TestClientConfiguration extends BaseClientConfiguration {
+        private TestClientConfiguration(TestClientConfigurationBuilder builder) {
+            super(builder);
+        }
+
+        public static TestClientConfigurationBuilder builder() {
+            return new TestClientConfigurationBuilder();
+        }
+
+        @Override
+        public BaseSubscriptionConfiguration getSubscriptionConfiguration() {
+            return null;
+        }
+
+        public static class TestClientConfigurationBuilder
+                extends BaseClientConfigurationBuilder<
+                        TestClientConfiguration, TestClientConfigurationBuilder> {
+            @Override
+            protected TestClientConfigurationBuilder self() {
+                return this;
+            }
+
+            @Override
+            public TestClientConfiguration build() {
+                return new TestClientConfiguration(this);
+            }
+        }
+    }
+
+    @Test
+    public void testDatabaseIdDefault() {
+        // Test that databaseId defaults to null when not specified
+        TestClientConfiguration config = TestClientConfiguration.builder().build();
+        assertNull(config.getDatabaseId());
+    }
+
+    @ParameterizedTest
+    @ValueSource(ints = {0, 1, 5, 10, 15, 50, 100, 1000})
+    public void testDatabaseIdValidRange(int databaseId) {
+        // Test that non-negative database IDs are accepted (server-side validation will handle range
+        // checks)
+        TestClientConfiguration config =
+                TestClientConfiguration.builder().databaseId(databaseId).build();
+        assertEquals(databaseId, config.getDatabaseId());
+    }
+}

java/integTest/src/test/java/glide/cluster/ClusterClientTests.java

@@ -154,6 +154,24 @@ public void client_name() {
         client.close();
     }
 
+    @SneakyThrows
+    @Test
+    public void select_cluster_database_id() {
+        String minVersion = "9.0.0";
+        assumeTrue(
+                SERVER_VERSION.isGreaterThanOrEqualTo(minVersion),
+                "Valkey version required >= " + minVersion);
+
+        GlideClusterClient client =
+                GlideClusterClient.createClient(commonClusterClientConfig().databaseId(4).build()).get();
+
+        String clientInfo =
+                (String) client.customCommand(new String[] {"CLIENT", "INFO"}).get().getSingleValue();
+        assertTrue(clientInfo.contains("db=4"));
+
+        client.close();
+    }
+
     @Test
     @SneakyThrows
     public void closed_client_throws_ExecutionException_with_ClosingException_as_cause() {