From 556a2c54e654538c1b0e7f44e5c3f7e679caf632 Mon Sep 17 00:00:00 2001
From: Akash Anand <aakashanand@google.com>
Date: Wed, 23 Apr 2025 16:58:56 +0530
Subject: [PATCH 1/8] feat: support option for setting client-id

---
 .../com/google/cloud/spanner/Spanner.java     | 23 +++++++++++
 .../com/google/cloud/spanner/SpannerImpl.java |  5 ++-
 .../spanner/connection/ConnectionImpl.java    | 39 +++++++++++++++----
 .../spanner/connection/ConnectionOptions.java |  7 +++-
 .../connection/ConnectionProperties.java      |  8 ++++
 .../google/cloud/spanner/SpannerImplTest.java | 34 ++++++++++++++++
 6 files changed, 106 insertions(+), 10 deletions(-)

diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
index 7ccbc88d978..f4b6cda894f 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
@@ -125,6 +125,29 @@ public interface Spanner extends Service<SpannerOptions>, AutoCloseable {
    */
   DatabaseClient getDatabaseClient(DatabaseId db);
 
+
+  /**
+   * Returns a {@code DatabaseClient} for the given database and given client id. It uses a pool of sessions to talk to
+   * the database.
+   * <!--SNIPPET get_db_client-->
+   *
+   * <pre>{@code
+   * SpannerOptions options = SpannerOptions.newBuilder().build();
+   * Spanner spanner = options.getService();
+   * final String project = "test-project";
+   * final String instance = "test-instance";
+   * final String database = "example-db";
+   * final String client_id = "client_id"
+   * DatabaseId db =
+   *     DatabaseId.of(project, instance, database);
+   *
+   * DatabaseClient dbClient = spanner.getDatabaseClient(db, client_id);
+   * }</pre>
+   *
+   * <!--SNIPPET get_db_client-->
+   */
+  DatabaseClient getDatabaseClient(DatabaseId db, String clientId);
+
   /**
    * Returns a {@code BatchClient} to do batch operations on Cloud Spanner databases. Batch client
    * is useful when one wants to read/query a large amount of data from Cloud Spanner across
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
index 63d501fbe63..dc1392480ea 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
@@ -254,9 +254,12 @@ public InstanceAdminClient getInstanceAdminClient() {
 
   @Override
   public DatabaseClient getDatabaseClient(DatabaseId db) {
+    return getDatabaseClient(db, null);
+  }
+
+  public DatabaseClient getDatabaseClient(DatabaseId db, String clientId) {
     synchronized (this) {
       checkClosed();
-      String clientId = null;
       if (dbClients.containsKey(db) && !dbClients.get(db).isValid()) {
         // Close the invalidated client and remove it.
         dbClients.get(db).closeAsync(new ClosedException());
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
index c1e8839534f..482be295df9 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
@@ -108,6 +108,7 @@
 import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 import java.util.Stack;
 import java.util.UUID;
@@ -157,6 +158,7 @@ class ConnectionImpl implements Connection {
   private static final ParsedStatement RELEASE_STATEMENT =
       AbstractStatementParser.getInstance(Dialect.GOOGLE_STANDARD_SQL)
           .parse(Statement.of("RELEASE s1"));
+  private static final String CLIENT_ID = "client_id";
 
   /**
    * Exception that is used to register the stacktrace of the code that opened a {@link Connection}.
@@ -251,8 +253,8 @@ static UnitOfWorkType of(TransactionMode transactionMode) {
     }
   }
 
-  private StatementExecutor.StatementTimeout statementTimeout =
-      new StatementExecutor.StatementTimeout();
+  private StatementTimeout statementTimeout =
+      new StatementTimeout();
   private boolean closed = false;
 
   private final Spanner spanner;
@@ -323,7 +325,28 @@ static UnitOfWorkType of(TransactionMode transactionMode) {
       EmulatorUtil.maybeCreateInstanceAndDatabase(
           spanner, options.getDatabaseId(), options.getDialect());
     }
-    this.dbClient = spanner.getDatabaseClient(options.getDatabaseId());
+    DatabaseClient tempDbClient = null;
+    try {
+      final Map<String, ConnectionPropertyValue<?>> propertyValueMap = options.getInitialConnectionPropertyValues();
+      String clientIdString = null;
+      if (propertyValueMap != null) {
+        final ConnectionPropertyValue<?> clientIdProp = propertyValueMap.get(CLIENT_ID);
+        if (clientIdProp != null) {
+          Object value = clientIdProp.getValue();
+          if (value != null) {
+            clientIdString = value.toString();
+          }
+        }
+        if (clientIdString != null && !clientIdString.isEmpty()) {
+          tempDbClient = spanner.getDatabaseClient(options.getDatabaseId(), clientIdString);
+        }
+      } else {
+        tempDbClient = spanner.getDatabaseClient(options.getDatabaseId());
+      }
+    } catch(Exception e) {
+      tempDbClient = spanner.getDatabaseClient(options.getDatabaseId());
+    }
+    this.dbClient = tempDbClient;
     this.batchClient = spanner.getBatchClient(options.getDatabaseId());
     this.ddlClient = createDdlClient();
     this.connectionState =
@@ -411,7 +434,7 @@ static Attributes createOpenTelemetryAttributes(DatabaseId databaseId) {
   }
 
   @VisibleForTesting
-  ConnectionState.Type getConnectionStateType() {
+  Type getConnectionStateType() {
     return this.connectionState.getType();
   }
 
@@ -500,7 +523,7 @@ private void reset(Context context, boolean inTransaction) {
 
     this.connectionState.resetValue(AUTOCOMMIT_DML_MODE, context, inTransaction);
     this.statementTag = null;
-    this.statementTimeout = new StatementExecutor.StatementTimeout();
+    this.statementTimeout = new StatementTimeout();
     this.connectionState.resetValue(DIRECTED_READ, context, inTransaction);
     this.connectionState.resetValue(SAVEPOINT_SUPPORT, context, inTransaction);
     this.protoDescriptors = null;
@@ -542,7 +565,7 @@ public boolean isClosed() {
   }
 
   private <T> T getConnectionPropertyValue(
-      com.google.cloud.spanner.connection.ConnectionProperty<T> property) {
+      ConnectionProperty<T> property) {
     return this.connectionState.getValue(property).getValue();
   }
 
@@ -563,8 +586,8 @@ private <T> void setConnectionPropertyValue(
    * Sets a connection property value only for the duration of the current transaction. The effects
    * of this will be undone once the transaction ends, regardless whether the transaction is
    * committed or rolled back. 'Local' properties are supported for both {@link
-   * com.google.cloud.spanner.connection.ConnectionState.Type#TRANSACTIONAL} and {@link
-   * com.google.cloud.spanner.connection.ConnectionState.Type#NON_TRANSACTIONAL} connection states.
+   * Type#TRANSACTIONAL} and {@link
+   * Type#NON_TRANSACTIONAL} connection states.
    *
    * <p>NOTE: This feature is not yet exposed in the public API.
    */
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionOptions.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionOptions.java
index 6f945938df0..a09c6872753 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionOptions.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionOptions.java
@@ -46,6 +46,7 @@
 import static com.google.cloud.spanner.connection.ConnectionProperties.RETURN_COMMIT_STATS;
 import static com.google.cloud.spanner.connection.ConnectionProperties.ROUTE_TO_LEADER;
 import static com.google.cloud.spanner.connection.ConnectionProperties.TRACING_PREFIX;
+import static com.google.cloud.spanner.connection.ConnectionProperties.CLIENT_ID;
 import static com.google.cloud.spanner.connection.ConnectionProperties.TRACK_CONNECTION_LEAKS;
 import static com.google.cloud.spanner.connection.ConnectionProperties.TRACK_SESSION_LEAKS;
 import static com.google.cloud.spanner.connection.ConnectionProperties.USER_AGENT;
@@ -539,6 +540,11 @@ public Builder setTracingPrefix(String tracingPrefix) {
       return this;
     }
 
+    public Builder setClientId(String clientId) {
+      setConnectionPropertyValue(CLIENT_ID, clientId);
+      return this;
+    }
+
     /** @return the {@link ConnectionOptions} */
     public ConnectionOptions build() {
       Preconditions.checkState(this.uri != null, "Connection URI is required");
@@ -603,7 +609,6 @@ private ConnectionOptions(Builder builder) {
 
     // Create the initial connection state from the parsed properties in the connection URL.
     this.initialConnectionState = new ConnectionState(connectionPropertyValues);
-
     // Check that at most one of credentials location, encoded credentials, credentials provider and
     // OUAuth token has been specified in the connection URI.
     Preconditions.checkArgument(
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionProperties.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionProperties.java
index 54d3461b787..22f541f3bd2 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionProperties.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionProperties.java
@@ -135,6 +135,14 @@ public class ConnectionProperties {
 
   private static final Boolean[] BOOLEANS = new Boolean[] {Boolean.TRUE, Boolean.FALSE};
 
+  static final ConnectionProperty<String> CLIENT_ID =
+      create(
+          "client_id",
+          "Client Id to use for this connection. Can only be set at the start up time",
+          null,
+          StringValueConverter.INSTANCE,
+          Context.STARTUP);
+
   static final ConnectionProperty<ConnectionState.Type> CONNECTION_STATE_TYPE =
       create(
           "connection_state_type",
diff --git a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerImplTest.java b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerImplTest.java
index 3cf13dc58d3..609d8b98365 100644
--- a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerImplTest.java
+++ b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerImplTest.java
@@ -358,6 +358,40 @@ public void testCreateInstanceAdminClient_whenMockAdminSettings_assertException(
     assertNotNull(instanceAdminClient);
   }
 
+  @Test
+  public void testGetDatabaseClient_when_clientId_is_not_null() {
+    String dbName =
+        String.format("projects/p1/instances/i1/databases/%s", UUID.randomUUID().toString());
+    DatabaseId db = DatabaseId.of(dbName);
+
+    Mockito.when(spannerOptions.getTransportOptions())
+        .thenReturn(GrpcTransportOptions.newBuilder().build());
+    Mockito.when(spannerOptions.getSessionPoolOptions())
+        .thenReturn(SessionPoolOptions.newBuilder().setMinSessions(0).build());
+    Mockito.when(spannerOptions.getDatabaseRole()).thenReturn("role");
+
+    DatabaseClientImpl databaseClient = (DatabaseClientImpl) impl.getDatabaseClient(db, "clientId-1");
+    assertThat(databaseClient.clientId).isEqualTo("clientId-1");
+
+    // Get same db client again.
+    DatabaseClientImpl databaseClient1 = (DatabaseClientImpl) impl.getDatabaseClient(db, "clientId-1");
+    assertThat(databaseClient1.clientId).isEqualTo(databaseClient.clientId);
+
+    // Get a db client for a different database.
+    String dbName2 =
+        String.format("projects/p1/instances/i1/databases/%s", UUID.randomUUID().toString());
+    DatabaseId db2 = DatabaseId.of(dbName2);
+    DatabaseClientImpl databaseClient2 = (DatabaseClientImpl) impl.getDatabaseClient(db2, "clientId-1");
+    assertThat(databaseClient2.clientId).isEqualTo("clientId-1");
+
+    // Getting a new database client for an invalidated database should use the same client id.
+    databaseClient.pool.setResourceNotFoundException(
+        new DatabaseNotFoundException(DoNotConstructDirectly.ALLOWED, "not found", null, null));
+    DatabaseClientImpl revalidated = (DatabaseClientImpl) impl.getDatabaseClient(db, "clientId-1");
+    assertThat(revalidated).isNotSameInstanceAs(databaseClient);
+    assertThat(revalidated.clientId).isEqualTo(databaseClient.clientId);
+  }
+
   private void closeSpannerAndIncludeStacktrace(Spanner spanner) {
     spanner.close();
   }

From d814755daf86e44c38e92af1e97dee5e929301e3 Mon Sep 17 00:00:00 2001
From: Akash Anand <aakashanand@google.com>
Date: Wed, 23 Apr 2025 18:00:27 +0530
Subject: [PATCH 2/8] feat: support option for setting client-id

---
 .../com/google/cloud/spanner/connection/ConnectionImpl.java    | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
index 482be295df9..90c2b164cb7 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
@@ -340,6 +340,9 @@ static UnitOfWorkType of(TransactionMode transactionMode) {
         if (clientIdString != null && !clientIdString.isEmpty()) {
           tempDbClient = spanner.getDatabaseClient(options.getDatabaseId(), clientIdString);
         }
+        else {
+          tempDbClient = spanner.getDatabaseClient(options.getDatabaseId());
+        }
       } else {
         tempDbClient = spanner.getDatabaseClient(options.getDatabaseId());
       }

From 3c587df30dba573017b7c73351c13152a5621798 Mon Sep 17 00:00:00 2001
From: Akash Anand <aakashanand@google.com>
Date: Wed, 23 Apr 2025 18:13:45 +0530
Subject: [PATCH 3/8] feat: support option for setting client-id

---
 .../spanner/connection/ConnectionImpl.java    | 37 +++++++++----------
 1 file changed, 18 insertions(+), 19 deletions(-)

diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
index 90c2b164cb7..c60b665be91 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
@@ -109,6 +109,7 @@
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.Stack;
 import java.util.UUID;
@@ -326,28 +327,18 @@ static UnitOfWorkType of(TransactionMode transactionMode) {
           spanner, options.getDatabaseId(), options.getDialect());
     }
     DatabaseClient tempDbClient = null;
+    final DatabaseId databaseId = options.getDatabaseId();
     try {
-      final Map<String, ConnectionPropertyValue<?>> propertyValueMap = options.getInitialConnectionPropertyValues();
-      String clientIdString = null;
-      if (propertyValueMap != null) {
-        final ConnectionPropertyValue<?> clientIdProp = propertyValueMap.get(CLIENT_ID);
-        if (clientIdProp != null) {
-          Object value = clientIdProp.getValue();
-          if (value != null) {
-            clientIdString = value.toString();
-          }
-        }
-        if (clientIdString != null && !clientIdString.isEmpty()) {
-          tempDbClient = spanner.getDatabaseClient(options.getDatabaseId(), clientIdString);
-        }
-        else {
-          tempDbClient = spanner.getDatabaseClient(options.getDatabaseId());
-        }
-      } else {
-        tempDbClient = spanner.getDatabaseClient(options.getDatabaseId());
+      Optional<String> clientIdOpt = extractClientIdOptional(options);
+      if(clientIdOpt.isPresent()) {
+        tempDbClient = spanner.getDatabaseClient(databaseId, clientIdOpt.get());
       }
     } catch(Exception e) {
-      tempDbClient = spanner.getDatabaseClient(options.getDatabaseId());
+      System.err.println("WARNING: Failed during DatabaseClient initialization (possibly getting specific ID), falling back to default. Error: "
+          + e.getMessage());
+    }
+    if(tempDbClient == null) {
+      tempDbClient = spanner.getDatabaseClient(databaseId);
     }
     this.dbClient = tempDbClient;
     this.batchClient = spanner.getBatchClient(options.getDatabaseId());
@@ -366,6 +357,14 @@ && getDialect() == Dialect.POSTGRESQL
     setDefaultTransactionOptions(getDefaultIsolationLevel());
   }
 
+  private Optional<String> extractClientIdOptional(ConnectionOptions options) {
+    return Optional.ofNullable(options.getInitialConnectionPropertyValues())
+        .map(props -> props.get(CLIENT_ID))
+        .map(ConnectionPropertyValue::getValue)
+        .map(Object::toString)
+        .filter(id -> !id.isEmpty());
+  }
+
   /** Constructor only for test purposes. */
   @VisibleForTesting
   ConnectionImpl(

From 27c1d9598900d21e5bbb73a090fef5c77a93d0ff Mon Sep 17 00:00:00 2001
From: Akash Anand <aakashanand@google.com>
Date: Wed, 23 Apr 2025 18:18:07 +0530
Subject: [PATCH 4/8] feat: support option for setting client-id

---
 .../com/google/cloud/spanner/Spanner.java     |  5 ++--
 .../spanner/connection/ConnectionImpl.java    | 23 ++++++++-----------
 .../spanner/connection/ConnectionOptions.java |  2 +-
 .../google/cloud/spanner/SpannerImplTest.java |  9 +++++---
 4 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
index f4b6cda894f..54a7f91d4a9 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
@@ -125,10 +125,9 @@ public interface Spanner extends Service<SpannerOptions>, AutoCloseable {
    */
   DatabaseClient getDatabaseClient(DatabaseId db);
 
-
   /**
-   * Returns a {@code DatabaseClient} for the given database and given client id. It uses a pool of sessions to talk to
-   * the database.
+   * Returns a {@code DatabaseClient} for the given database and given client id. It uses a pool of
+   * sessions to talk to the database.
    * <!--SNIPPET get_db_client-->
    *
    * <pre>{@code
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
index c60b665be91..dc03b68dbb7 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
@@ -108,7 +108,6 @@
 import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
-import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
 import java.util.Stack;
@@ -254,8 +253,7 @@ static UnitOfWorkType of(TransactionMode transactionMode) {
     }
   }
 
-  private StatementTimeout statementTimeout =
-      new StatementTimeout();
+  private StatementTimeout statementTimeout = new StatementTimeout();
   private boolean closed = false;
 
   private final Spanner spanner;
@@ -330,14 +328,15 @@ static UnitOfWorkType of(TransactionMode transactionMode) {
     final DatabaseId databaseId = options.getDatabaseId();
     try {
       Optional<String> clientIdOpt = extractClientIdOptional(options);
-      if(clientIdOpt.isPresent()) {
+      if (clientIdOpt.isPresent()) {
         tempDbClient = spanner.getDatabaseClient(databaseId, clientIdOpt.get());
       }
-    } catch(Exception e) {
-      System.err.println("WARNING: Failed during DatabaseClient initialization (possibly getting specific ID), falling back to default. Error: "
-          + e.getMessage());
+    } catch (Exception e) {
+      System.err.println(
+          "WARNING: Failed during DatabaseClient initialization (possibly getting specific ID), falling back to default. Error: "
+              + e.getMessage());
     }
-    if(tempDbClient == null) {
+    if (tempDbClient == null) {
       tempDbClient = spanner.getDatabaseClient(databaseId);
     }
     this.dbClient = tempDbClient;
@@ -566,8 +565,7 @@ public boolean isClosed() {
     return closed;
   }
 
-  private <T> T getConnectionPropertyValue(
-      ConnectionProperty<T> property) {
+  private <T> T getConnectionPropertyValue(ConnectionProperty<T> property) {
     return this.connectionState.getValue(property).getValue();
   }
 
@@ -587,9 +585,8 @@ private <T> void setConnectionPropertyValue(
   /**
    * Sets a connection property value only for the duration of the current transaction. The effects
    * of this will be undone once the transaction ends, regardless whether the transaction is
-   * committed or rolled back. 'Local' properties are supported for both {@link
-   * Type#TRANSACTIONAL} and {@link
-   * Type#NON_TRANSACTIONAL} connection states.
+   * committed or rolled back. 'Local' properties are supported for both {@link Type#TRANSACTIONAL}
+   * and {@link Type#NON_TRANSACTIONAL} connection states.
    *
    * <p>NOTE: This feature is not yet exposed in the public API.
    */
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionOptions.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionOptions.java
index a09c6872753..fbc59caa174 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionOptions.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionOptions.java
@@ -21,6 +21,7 @@
 import static com.google.cloud.spanner.connection.ConnectionProperties.AUTO_PARTITION_MODE;
 import static com.google.cloud.spanner.connection.ConnectionProperties.CHANNEL_PROVIDER;
 import static com.google.cloud.spanner.connection.ConnectionProperties.CLIENT_CERTIFICATE;
+import static com.google.cloud.spanner.connection.ConnectionProperties.CLIENT_ID;
 import static com.google.cloud.spanner.connection.ConnectionProperties.CLIENT_KEY;
 import static com.google.cloud.spanner.connection.ConnectionProperties.CREDENTIALS_PROVIDER;
 import static com.google.cloud.spanner.connection.ConnectionProperties.CREDENTIALS_URL;
@@ -46,7 +47,6 @@
 import static com.google.cloud.spanner.connection.ConnectionProperties.RETURN_COMMIT_STATS;
 import static com.google.cloud.spanner.connection.ConnectionProperties.ROUTE_TO_LEADER;
 import static com.google.cloud.spanner.connection.ConnectionProperties.TRACING_PREFIX;
-import static com.google.cloud.spanner.connection.ConnectionProperties.CLIENT_ID;
 import static com.google.cloud.spanner.connection.ConnectionProperties.TRACK_CONNECTION_LEAKS;
 import static com.google.cloud.spanner.connection.ConnectionProperties.TRACK_SESSION_LEAKS;
 import static com.google.cloud.spanner.connection.ConnectionProperties.USER_AGENT;
diff --git a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerImplTest.java b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerImplTest.java
index 609d8b98365..af73b2b7e5f 100644
--- a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerImplTest.java
+++ b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerImplTest.java
@@ -370,18 +370,21 @@ public void testGetDatabaseClient_when_clientId_is_not_null() {
         .thenReturn(SessionPoolOptions.newBuilder().setMinSessions(0).build());
     Mockito.when(spannerOptions.getDatabaseRole()).thenReturn("role");
 
-    DatabaseClientImpl databaseClient = (DatabaseClientImpl) impl.getDatabaseClient(db, "clientId-1");
+    DatabaseClientImpl databaseClient =
+        (DatabaseClientImpl) impl.getDatabaseClient(db, "clientId-1");
     assertThat(databaseClient.clientId).isEqualTo("clientId-1");
 
     // Get same db client again.
-    DatabaseClientImpl databaseClient1 = (DatabaseClientImpl) impl.getDatabaseClient(db, "clientId-1");
+    DatabaseClientImpl databaseClient1 =
+        (DatabaseClientImpl) impl.getDatabaseClient(db, "clientId-1");
     assertThat(databaseClient1.clientId).isEqualTo(databaseClient.clientId);
 
     // Get a db client for a different database.
     String dbName2 =
         String.format("projects/p1/instances/i1/databases/%s", UUID.randomUUID().toString());
     DatabaseId db2 = DatabaseId.of(dbName2);
-    DatabaseClientImpl databaseClient2 = (DatabaseClientImpl) impl.getDatabaseClient(db2, "clientId-1");
+    DatabaseClientImpl databaseClient2 =
+        (DatabaseClientImpl) impl.getDatabaseClient(db2, "clientId-1");
     assertThat(databaseClient2.clientId).isEqualTo("clientId-1");
 
     // Getting a new database client for an invalidated database should use the same client id.

From c770b77e2962762ea9432c301b9842ec12260b2f Mon Sep 17 00:00:00 2001
From: Akash Anand <aakashanand@google.com>
Date: Wed, 23 Apr 2025 18:56:10 +0530
Subject: [PATCH 5/8] feat: support option for setting client-id

---
 google-cloud-spanner/clirr-ignored-differences.xml         | 7 +++++++
 .../src/main/java/com/google/cloud/spanner/Spanner.java    | 4 +++-
 .../main/java/com/google/cloud/spanner/SpannerImpl.java    | 1 +
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/google-cloud-spanner/clirr-ignored-differences.xml b/google-cloud-spanner/clirr-ignored-differences.xml
index d6d36b0e147..2d934fb1b2b 100644
--- a/google-cloud-spanner/clirr-ignored-differences.xml
+++ b/google-cloud-spanner/clirr-ignored-differences.xml
@@ -957,4 +957,11 @@
     <className>com/google/cloud/spanner/DatabaseClient</className>
     <method>com.google.cloud.spanner.Statement$StatementFactory getStatementFactory()</method>
   </difference>
+
+  <difference>
+    <differenceType>7012</differenceType>
+    <className>com/google/cloud/spanner/Spanner</className>
+    <method>com.google.cloud.spanner.DatabaseClient getDatabaseClient(com.google.cloud.spanner.DatabaseId, java.lang.String)</method>
+    <justification>Added as default method for JDBC client ID support. Default implementation throws UnsupportedOperationException to maintain binary compatibility for existing implementers.</justification>
+  </difference>
 </differences>
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
index 54a7f91d4a9..1fa21d9f870 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
@@ -145,7 +145,9 @@ public interface Spanner extends Service<SpannerOptions>, AutoCloseable {
    *
    * <!--SNIPPET get_db_client-->
    */
-  DatabaseClient getDatabaseClient(DatabaseId db, String clientId);
+  default DatabaseClient getDatabaseClient(DatabaseId db, String clientId) {
+    throw new UnsupportedOperationException("getDatabaseClient with clientId is not supported by this default implementation.");
+  }
 
   /**
    * Returns a {@code BatchClient} to do batch operations on Cloud Spanner databases. Batch client
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
index dc1392480ea..6aad072c97a 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
@@ -257,6 +257,7 @@ public DatabaseClient getDatabaseClient(DatabaseId db) {
     return getDatabaseClient(db, null);
   }
 
+  @Override
   public DatabaseClient getDatabaseClient(DatabaseId db, String clientId) {
     synchronized (this) {
       checkClosed();

From b2079f4064dcce1b977450806929130e9e3d3d55 Mon Sep 17 00:00:00 2001
From: Akash Anand <aakashanand@google.com>
Date: Thu, 24 Apr 2025 13:06:54 +0530
Subject: [PATCH 6/8] feat: support option for setting client-id

---
 .../src/main/java/com/google/cloud/spanner/Spanner.java        | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
index 1fa21d9f870..587a95ace63 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
@@ -146,7 +146,8 @@ public interface Spanner extends Service<SpannerOptions>, AutoCloseable {
    * <!--SNIPPET get_db_client-->
    */
   default DatabaseClient getDatabaseClient(DatabaseId db, String clientId) {
-    throw new UnsupportedOperationException("getDatabaseClient with clientId is not supported by this default implementation.");
+    throw new UnsupportedOperationException(
+        "getDatabaseClient with clientId is not supported by this default implementation.");
   }
 
   /**

From a2f790a274bd1c3d4f4291ddfb1f79a213a6c91b Mon Sep 17 00:00:00 2001
From: Akash Anand <aakashanand@google.com>
Date: Thu, 24 Apr 2025 16:45:44 +0530
Subject: [PATCH 7/8] feat: support option for setting client-id

---
 .../clirr-ignored-differences.xml             |  7 -----
 .../google/cloud/spanner/ExtendedSpanner.java | 28 +++++++++++++++++++
 .../com/google/cloud/spanner/Spanner.java     | 25 -----------------
 .../com/google/cloud/spanner/SpannerImpl.java |  2 +-
 .../spanner/connection/ConnectionImpl.java    |  8 ++++--
 5 files changed, 35 insertions(+), 35 deletions(-)
 create mode 100644 google-cloud-spanner/src/main/java/com/google/cloud/spanner/ExtendedSpanner.java

diff --git a/google-cloud-spanner/clirr-ignored-differences.xml b/google-cloud-spanner/clirr-ignored-differences.xml
index 83ad125f7e1..28e22e4a86c 100644
--- a/google-cloud-spanner/clirr-ignored-differences.xml
+++ b/google-cloud-spanner/clirr-ignored-differences.xml
@@ -964,11 +964,4 @@
     <className>com/google/cloud/spanner/DatabaseClient</className>
     <method>com.google.cloud.spanner.Statement$StatementFactory getStatementFactory()</method>
   </difference>
-
-  <difference>
-    <differenceType>7012</differenceType>
-    <className>com/google/cloud/spanner/Spanner</className>
-    <method>com.google.cloud.spanner.DatabaseClient getDatabaseClient(com.google.cloud.spanner.DatabaseId, java.lang.String)</method>
-    <justification>Added as default method for JDBC client ID support. Default implementation throws UnsupportedOperationException to maintain binary compatibility for existing implementers.</justification>
-  </difference>
 </differences>
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/ExtendedSpanner.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/ExtendedSpanner.java
new file mode 100644
index 00000000000..58f80c86e2f
--- /dev/null
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/ExtendedSpanner.java
@@ -0,0 +1,28 @@
+package com.google.cloud.spanner;
+
+public interface ExtendedSpanner extends Spanner {
+  /**
+   * Returns a {@code DatabaseClient} for the given database and given client id. It uses a pool of
+   * sessions to talk to the database.
+   * <!--SNIPPET get_db_client-->
+   *
+   * <pre>{@code
+   * SpannerOptions options = SpannerOptions.newBuilder().build();
+   * Spanner spanner = options.getService();
+   * final String project = "test-project";
+   * final String instance = "test-instance";
+   * final String database = "example-db";
+   * final String client_id = "client_id"
+   * DatabaseId db =
+   *     DatabaseId.of(project, instance, database);
+   *
+   * DatabaseClient dbClient = spanner.getDatabaseClient(db, client_id);
+   * }</pre>
+   *
+   * <!--SNIPPET get_db_client-->
+   */
+  default DatabaseClient getDatabaseClient(DatabaseId db, String clientId) {
+    throw new UnsupportedOperationException(
+        "getDatabaseClient with clientId is not supported by this default implementation.");
+  }
+}
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
index 587a95ace63..7ccbc88d978 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Spanner.java
@@ -125,31 +125,6 @@ public interface Spanner extends Service<SpannerOptions>, AutoCloseable {
    */
   DatabaseClient getDatabaseClient(DatabaseId db);
 
-  /**
-   * Returns a {@code DatabaseClient} for the given database and given client id. It uses a pool of
-   * sessions to talk to the database.
-   * <!--SNIPPET get_db_client-->
-   *
-   * <pre>{@code
-   * SpannerOptions options = SpannerOptions.newBuilder().build();
-   * Spanner spanner = options.getService();
-   * final String project = "test-project";
-   * final String instance = "test-instance";
-   * final String database = "example-db";
-   * final String client_id = "client_id"
-   * DatabaseId db =
-   *     DatabaseId.of(project, instance, database);
-   *
-   * DatabaseClient dbClient = spanner.getDatabaseClient(db, client_id);
-   * }</pre>
-   *
-   * <!--SNIPPET get_db_client-->
-   */
-  default DatabaseClient getDatabaseClient(DatabaseId db, String clientId) {
-    throw new UnsupportedOperationException(
-        "getDatabaseClient with clientId is not supported by this default implementation.");
-  }
-
   /**
    * Returns a {@code BatchClient} to do batch operations on Cloud Spanner databases. Batch client
    * is useful when one wants to read/query a large amount of data from Cloud Spanner across
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
index 6aad072c97a..c4b11cc859d 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
@@ -59,7 +59,7 @@
 import javax.annotation.concurrent.GuardedBy;
 
 /** Default implementation of the Cloud Spanner interface. */
-class SpannerImpl extends BaseService<SpannerOptions> implements Spanner {
+class SpannerImpl extends BaseService<SpannerOptions> implements ExtendedSpanner {
   private static final Logger logger = Logger.getLogger(SpannerImpl.class.getName());
   final TraceWrapper tracer =
       new TraceWrapper(
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
index dc03b68dbb7..0c73ba11ffb 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionImpl.java
@@ -58,6 +58,7 @@
 import com.google.cloud.spanner.DatabaseId;
 import com.google.cloud.spanner.Dialect;
 import com.google.cloud.spanner.ErrorCode;
+import com.google.cloud.spanner.ExtendedSpanner;
 import com.google.cloud.spanner.Mutation;
 import com.google.cloud.spanner.Options;
 import com.google.cloud.spanner.Options.QueryOption;
@@ -328,8 +329,11 @@ static UnitOfWorkType of(TransactionMode transactionMode) {
     final DatabaseId databaseId = options.getDatabaseId();
     try {
       Optional<String> clientIdOpt = extractClientIdOptional(options);
-      if (clientIdOpt.isPresent()) {
-        tempDbClient = spanner.getDatabaseClient(databaseId, clientIdOpt.get());
+      if (clientIdOpt.isPresent() && !clientIdOpt.get().isEmpty()) {
+        if (this.spanner instanceof ExtendedSpanner) {
+          ExtendedSpanner extendedSpanner = (ExtendedSpanner) this.spanner;
+          tempDbClient = extendedSpanner.getDatabaseClient(databaseId, clientIdOpt.get());
+        }
       }
     } catch (Exception e) {
       System.err.println(

From c78ef3d4de70df5a60a4e5129169ba15ddaa5b8c Mon Sep 17 00:00:00 2001
From: Akash Anand <aakashanand@google.com>
Date: Thu, 24 Apr 2025 16:56:09 +0530
Subject: [PATCH 8/8] feat: support option for setting client-id

---
 .../google/cloud/spanner/ExtendedSpanner.java    | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/ExtendedSpanner.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/ExtendedSpanner.java
index 58f80c86e2f..a1b65ecfefb 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/ExtendedSpanner.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/ExtendedSpanner.java
@@ -1,3 +1,19 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package com.google.cloud.spanner;
 
 public interface ExtendedSpanner extends Spanner {