Google Cloud Spanner Client for Java

Java idiomatic client for Cloud Spanner.

• Product Documentation
• Client Library Documentation

Quickstart

If you are using Maven with BOM, add this to your pom.xml file:

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>com.google.cloud</groupId>
      <artifactId>libraries-bom</artifactId>
      <version>26.50.0</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

<dependencies>
  <dependency>
    <groupId>com.google.cloud</groupId>
    <artifactId>google-cloud-spanner</artifactId>
  </dependency>

If you are using Maven without the BOM, add this to your dependencies:

<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-spanner</artifactId>
  <version>6.81.0</version>
</dependency>

If you are using Gradle 5.x or later, add this to your dependencies:

implementation platform('com.google.cloud:libraries-bom:26.50.0')

implementation 'com.google.cloud:google-cloud-spanner'

If you are using Gradle without BOM, add this to your dependencies:

implementation 'com.google.cloud:google-cloud-spanner:6.81.1'

If you are using SBT, add this to your dependencies:

libraryDependencies += "com.google.cloud" % "google-cloud-spanner" % "6.81.1"

Authentication

See the Authentication section in the base directory's README.

Authorization

The client application making API calls must be granted authorization scopes required for the desired Cloud Spanner APIs, and the authenticated principal must have the IAM role(s) required to access GCP resources using the Cloud Spanner API calls.

Getting Started

Prerequisites

You will need a Google Cloud Platform Console project with the Cloud Spanner API enabled. You will need to enable billing to use Google Cloud Spanner. Follow these instructions to get your project set up. You will also need to set up the local development environment by installing the Google Cloud Command Line Interface and running the following commands in command line: gcloud auth login and gcloud config set project [YOUR PROJECT ID].

Installation and setup

You'll need to obtain the google-cloud-spanner library. See the Quickstart section to add google-cloud-spanner as a dependency in your code.

About Cloud Spanner

Cloud Spanner is a fully managed, mission-critical, relational database service that offers transactional consistency at global scale, \nschemas, SQL (ANSI 2011 with extensions), and automatic, synchronous replication \nfor high availability.\n\nBe sure to activate the Cloud Spanner API on the Developer's Console to\nuse Cloud Spanner from your project.

See the Cloud Spanner client library docs to learn how to use this Cloud Spanner Client Library.

Calling Cloud Spanner

Here is a code snippet showing a simple usage example. Add the following imports at the top of your file:

import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.ResultSet;
import com.google.cloud.spanner.Spanner;
import com.google.cloud.spanner.SpannerOptions;
import com.google.cloud.spanner.Statement;

Then, to make a query to Spanner, use the following code:

// Instantiates a client
SpannerOptions options = SpannerOptions.newBuilder().build();
Spanner spanner = options.getService();
String instance = "my-instance";
String database = "my-database";
try {
  // Creates a database client
  DatabaseClient dbClient = spanner.getDatabaseClient(
    DatabaseId.of(options.getProjectId(), instance, database));
  // Queries the database
  try (ResultSet resultSet = dbClient.singleUse().executeQuery(Statement.of("SELECT 1"))) {
    // Prints the results
    while (resultSet.next()) {
      System.out.printf("%d\n", resultSet.getLong(0));
    }
  }
} finally {
  // Closes the client which will free up the resources used
  spanner.close();
}

Complete source code

In DatabaseSelect.java we put together all the code shown above in a single program.

Session Pool

The Cloud Spanner client maintains a session pool, as sessions are expensive to create and are intended to be long-lived. The client automatically takes a session from the pool and uses this executing queries and transactions. See Session Pool and Channel Pool Configuration for in-depth background information about sessions and gRPC channels and how these are handled in the Cloud Spanner Java client.

Metrics

Available client-side metrics:

• spanner/max_in_use_sessions: This returns the maximum number of sessions that have been in use during the last maintenance window interval, so as to provide an indication of the amount of activity currently in the database.

• spanner/max_allowed_sessions: This shows the maximum number of sessions allowed.

• spanner/num_sessions_in_pool: This metric allows users to see instance-level and database-level data for the total number of sessions in the pool at this very moment.

• spanner/num_acquired_sessions: This metric allows users to see the total number of acquired sessions.

• spanner/num_released_sessions: This metric allows users to see the total number of released (destroyed) sessions.

• spanner/get_session_timeouts: This gives you an indication of the total number of get session timed-out instead of being granted (the thread that requested the session is placed in a wait queue where it waits until a session is released into the pool by another thread) due to pool exhaustion since the server process started.

• spanner/gfe_latency: This metric shows latency between Google's network receiving an RPC and reading back the first byte of the response.

• spanner/gfe_header_missing_count: This metric shows the number of RPC responses received without the server-timing header, most likely indicating that the RPC never reached Google's network.

Instrument with OpenTelemetry

Cloud Spanner client supports OpenTelemetry Metrics, which gives insight into the client internals and aids in debugging/troubleshooting production issues. OpenTelemetry metrics will provide you with enough data to enable you to spot, and investigate the cause of any unusual deviations from normal behavior.

All Cloud Spanner Metrics are prefixed with spanner/ and uses cloud.google.com/java as Instrumentation Scope. The metrics will be tagged with:

• database: the target database name.
• instance_id: the instance id of the target Spanner instance.
• client_id: the user defined database client id.

By default, the functionality is disabled. You need to add OpenTelemetry dependencies, enable OpenTelemetry metrics and must configure the OpenTelemetry with appropriate exporters at the startup of your application:

OpenTelemetry Dependencies

If you are using Maven, add this to your pom.xml file

<dependency>
      <groupId>io.opentelemetry</groupId>
      <artifactId>opentelemetry-sdk</artifactId>
      <version>{opentelemetry.version}</version>
</dependency>
<dependency>
      <groupId>io.opentelemetry</groupId>
      <artifactId>opentelemetry-sdk-metrics</artifactId>
      <version>{opentelemetry.version}</version>
</dependency>
<dependency>
    <groupId>io.opentelemetry</groupId>
    <artifactId>opentelemetry-exporter-otlp</artifactId>
    <version>{opentelemetry.version}</version>
</dependency>

If you are using Gradle, add this to your dependencies

compile 'io.opentelemetry:opentelemetry-sdk:{opentelemetry.version}'
compile 'io.opentelemetry:opentelemetry-sdk-metrics:{opentelemetry.version}'
compile 'io.opentelemetry:opentelemetry-exporter-oltp:{opentelemetry.version}'

OpenTelemetry Configuration

By default, all metrics are disabled. To enable metrics and configure the OpenTelemetry follow below:

// Enable OpenTelemetry metrics before injecting OpenTelemetry object.
SpannerOptions.enableOpenTelemetryMetrics();

SdkMeterProvider sdkMeterProvider = SdkMeterProvider.builder()
// Use Otlp exporter or any other exporter of your choice.
  .registerMetricReader(PeriodicMetricReader.builder(OtlpGrpcMetricExporter.builder().build())
  .build())
  .build();

OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
        .setMeterProvider(sdkMeterProvider)
        .build()

SpannerOptions options = SpannerOptions.newBuilder()
// Inject OpenTelemetry object via Spanner Options or register OpenTelemetry object as Global
  .setOpenTelemetry(openTelemetry)
  .build();

Spanner spanner = options.getService();

OpenTelemetry SQL Statement Tracing

The OpenTelemetry traces that are generated by the Java client include any request and transaction tags that have been set. The traces can also include the SQL statements that are executed and the name of the thread that executes the statement. Enable this with the enableExtendedTracing option:

SpannerOptions options = SpannerOptions.newBuilder()
  .setOpenTelemetry(openTelemetry)
  .setEnableExtendedTracing(true)
  .build();

This option can also be enabled by setting the environment variable SPANNER_ENABLE_EXTENDED_TRACING=true.

OpenTelemetry API Tracing

You can enable tracing of each API call that the Spanner client executes with the enableApiTracing option. These traces also include any retry attempts for an API call:

SpannerOptions options = SpannerOptions.newBuilder()
.setOpenTelemetry(openTelemetry)
.setEnableApiTracing(true)
.build();

This option can also be enabled by setting the environment variable SPANNER_ENABLE_API_TRACING=true.

Note: The attribute keys that are used for additional information about retry attempts and the number of requests might change in a future release.

Instrument with OpenCensus

Note: OpenCensus project is deprecated. See Sunsetting OpenCensus. We recommend migrating to OpenTelemetry, the successor project.

Cloud Spanner client supports Opencensus Metrics, which gives insight into the client internals and aids in debugging/troubleshooting production issues. OpenCensus metrics will provide you with enough data to enable you to spot, and investigate the cause of any unusual deviations from normal behavior.

All Cloud Spanner Metrics are prefixed with cloud.google.com/java/spanner

The metrics are tagged with:

• database: the target database name.
• instance_id: the instance id of the target Spanner instance.
• client_id: the user defined database client id.
• library_version: the version of the library that you're using.

By default, the functionality is disabled. You need to include opencensus-impl dependency to collect the data and exporter dependency to export to backend.

Click here for more information.

OpenCensus Dependencies

If you are using Maven, add this to your pom.xml file

<dependency>
  <groupId>io.opencensus</groupId>
  <artifactId>opencensus-impl</artifactId>
  <version>0.30.0</version>
  <scope>runtime</scope>
</dependency>
<dependency>
  <groupId>io.opencensus</groupId>
  <artifactId>opencensus-exporter-stats-stackdriver</artifactId>
  <version>0.30.0</version>
</dependency>

If you are using Gradle, add this to your dependencies

compile 'io.opencensus:opencensus-impl:0.30.0'
compile 'io.opencensus:opencensus-exporter-stats-stackdriver:0.30.0'

Configure the OpenCensus Exporter

At the start of your application configure the exporter:

import io.opencensus.exporter.stats.stackdriver.StackdriverStatsExporter;
// Enable OpenCensus exporters to export metrics to Stackdriver Monitoring.
// Exporters use Application Default Credentials to authenticate.
// See https://developers.google.com/identity/protocols/application-default-credentials
// for more details.
// The minimum reporting period for Stackdriver is 1 minute.
StackdriverStatsExporter.createAndRegister();

Enable RPC Views

By default, all session metrics are enabled. To enable RPC views, use either of the following method:

// Register views for GFE metrics, including gfe_latency and gfe_header_missing_count.
SpannerRpcViews.registerGfeLatencyAndHeaderMissingCountViews();

// Register GFE Latency view. 
SpannerRpcViews.registerGfeLatencyView();

// Register GFE Header Missing Count view.
SpannerRpcViews.registerGfeHeaderMissingCountView();

Traces

Cloud Spanner client supports OpenTelemetry Traces, which gives insight into the client internals and aids in debugging/troubleshooting production issues.

By default, the functionality is disabled. You need to add OpenTelemetry dependencies, enable OpenTelemetry traces and must configure the OpenTelemetry with appropriate exporters at the startup of your application.

OpenTelemetry Dependencies

If you are using Maven, add this to your pom.xml file

<dependency>
      <groupId>io.opentelemetry</groupId>
      <artifactId>opentelemetry-sdk</artifactId>
      <version>{opentelemetry.version}</version>
</dependency>
<dependency>
      <groupId>io.opentelemetry</groupId>
      <artifactId>opentelemetry-sdk-trace</artifactId>
      <version>{opentelemetry.version}</version>
</dependency>
<dependency>
    <groupId>io.opentelemetry</groupId>
    <artifactId>opentelemetry-exporter-otlp</artifactId>
    <version>{opentelemetry.version}</version>
</dependency>

If you are using Gradle, add this to your dependencies

compile 'io.opentelemetry:opentelemetry-sdk:{opentelemetry.version}'
compile 'io.opentelemetry:opentelemetry-sdk-trace:{opentelemetry.version}'
compile 'io.opentelemetry:opentelemetry-exporter-oltp:{opentelemetry.version}'

OpenTelemetry Configuration

Note: Enabling OpenTelemetry traces will automatically disable OpenCensus traces.

// Enable OpenTelemetry traces
SpannerOptions.enableOpenTelemetryTraces();

// Create a new tracer provider
SdkTracerProvider sdkTracerProvider = SdkTracerProvider.builder()
      // Use Otlp exporter or any other exporter of your choice.
      .addSpanProcessor(SimpleSpanProcessor.builder(OtlpGrpcSpanExporter
          .builder().build()).build())
          .build();


OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
        .setTracerProvider(sdkTracerProvider)
        .build()

SpannerOptions options = SpannerOptions.newBuilder()
// Inject OpenTelemetry object via Spanner Options or register OpenTelmetry object as Global
  .setOpenTelemetry(openTelemetry)
  .build();

Spanner spanner = options.getService();

OpenTelemetry SQL Statement Tracing

The OpenTelemetry traces that are generated by the Java client include any request and transaction tags that have been set. The traces can also include the SQL statements that are executed and the name of the thread that executes the statement. Enable this with the enableExtendedTracing option:

SpannerOptions options = SpannerOptions.newBuilder()
  .setOpenTelemetry(openTelemetry)
  .setEnableExtendedTracing(true)
  .build();

This option can also be enabled by setting the environment variable SPANNER_ENABLE_EXTENDED_TRACING=true.

OpenTelemetry API Tracing

You can enable tracing of each API call that the Spanner client executes with the enableApiTracing option. These traces also include any retry attempts for an API call:

SpannerOptions options = SpannerOptions.newBuilder()
.setOpenTelemetry(openTelemetry)
.setEnableApiTracing(true)
.build();

This option can also be enabled by setting the environment variable SPANNER_ENABLE_API_TRACING=true.

Note: The attribute keys that are used for additional information about retry attempts and the number of requests might change in a future release.

Migrate from OpenCensus to OpenTelemetry

Using the OpenTelemetry OpenCensus Bridge, you can immediately begin exporting your metrics and traces with OpenTelemetry

Disable OpenCensus metrics

Disable OpenCensus metrics for Spanner by including the following code if you still possess OpenCensus dependencies and exporter.

SpannerOptions.disableOpenCensusMetrics();

Disable OpenCensus traces

Enabling OpenTelemetry traces for Spanner will automatically disable OpenCensus traces.

SpannerOptions.enableOpenTelemetryTraces();

Remove OpenCensus Dependencies and Code

Remove any OpenCensus-related code and dependencies from your codebase if all your dependencies are ready to move to OpenTelemetry.

• Remove the OpenCensus Exporters which were configured here
• Remove SpannerRPCViews reference which were configured here
• Remove the OpenCensus dependencies which were added here

Update your Dashboards and Alerts

Update your dashboards and alerts to reflect below changes

• Metrics name : cloud.google.com/java prefix has been removed from OpenTelemery metrics and instead has been added as Instrumenation Scope.
• Metrics namespace : OpenTelmetry exporters uses workload.googleapis.com namespace opposed to custom.googleapis.com with OpenCensus.

Samples

Samples are in the samples/ directory.

Sample	Source Code	Try it
Add And Drop Database Role	source code
Add Json Column Sample	source code
Add Jsonb Column Sample	source code
Add Numeric Column Sample	source code
Add Proto Column Sample	source code
Alter Sequence Sample	source code
Alter Table With Foreign Key Delete Cascade Sample	source code
Async Dml Example	source code
Async Query Example	source code
Async Query To List Async Example	source code
Async Read Example	source code
Async Read Only Transaction Example	source code
Async Read Row Example	source code
Async Read Using Index Example	source code
Async Runner Example	source code
Async Transaction Manager Example	source code
Batch Sample	source code
Batch Write At Least Once Sample	source code
Copy Backup Sample	source code
Create Backup With Encryption Key	source code
Create Database With Default Leader Sample	source code
Create Database With Encryption Key	source code
Create Database With Version Retention Period Sample	source code
Create Full Backup Schedule Sample	source code
Create Incremental Backup Schedule Sample	source code
Create Instance Config Sample	source code
Create Instance Example	source code
Create Instance Partition Sample	source code
Create Instance With Autoscaling Config Example	source code
Create Instance With Processing Units Example	source code
Create Sequence Sample	source code
Create Table With Foreign Key Delete Cascade Sample	source code
Custom Timeout And Retry Settings Example	source code
Delete Backup Schedule Sample	source code
Delete Instance Config Sample	source code
Delete Using Dml Returning Sample	source code
Directed Read Sample	source code
Drop Foreign Key Constraint Delete Cascade Sample	source code
Drop Sequence Sample	source code
Enable Fine Grained Access	source code
Get Backup Schedule Sample	source code
Get Commit Stats Sample	source code
Get Database Ddl Sample	source code
Get Instance Config Sample	source code
Insert Using Dml Returning Sample	source code
List Backup Schedules Sample	source code
List Database Roles	source code
List Databases Sample	source code
List Instance Config Operations Sample	source code
List Instance Configs Sample	source code
Pg Alter Sequence Sample	source code
Pg Async Query To List Async Example	source code
Pg Async Runner Example	source code
Pg Async Transaction Manager Example	source code
Pg Batch Dml Sample	source code
Pg Case Sensitivity Sample	source code
Pg Create Sequence Sample	source code
Pg Delete Using Dml Returning Sample	source code
Pg Drop Sequence Sample	source code
Pg Insert Using Dml Returning Sample	source code
Pg Interleaved Table Sample	source code
Pg Partitioned Dml Sample	source code
Pg Query With Numeric Parameter Sample	source code
Pg Spanner Sample	source code
Pg Update Using Dml Returning Sample	source code
Query Information Schema Database Options Sample	source code
Query With Json Parameter Sample	source code
Query With Jsonb Parameter Sample	source code
Query With Numeric Parameter Sample	source code
Query With Proto Parameter Sample	source code
Quickstart Sample	source code
Read Data With Database Role	source code
Restore Backup With Encryption Key	source code
Set Max Commit Delay Sample	source code
Singer Proto	source code
Spanner Graph Sample	source code
Spanner Sample	source code
Statement Timeout Example	source code
Tag Sample	source code
Tracing Sample	source code
Transaction Timeout Example	source code
Update Backup Schedule Sample	source code
Update Database Sample	source code
Update Database With Default Leader Sample	source code
Update Instance Config Sample	source code
Update Instance Example	source code
Update Json Data Sample	source code
Update Jsonb Data Sample	source code
Update Numeric Data Sample	source code
Update Proto Data Sample	source code
Update Proto Data Sample Using Dml	source code
Update Using Dml Returning Sample	source code
Add And Drop Database Role	source code
Add Json Column Sample	source code
Add Jsonb Column Sample	source code
Add Numeric Column Sample	source code
Alter Sequence Sample	source code
Alter Table With Foreign Key Delete Cascade Sample	source code
Copy Backup Sample	source code
Create Backup With Encryption Key	source code
Create Database With Default Leader Sample	source code
Create Database With Encryption Key	source code
Create Database With Version Retention Period Sample	source code
Create Instance Config Sample	source code
Create Instance Example	source code
Create Instance With Autoscaling Config Example	source code
Create Instance With Processing Units Example	source code
Create Sequence Sample	source code
Create Table With Foreign Key Delete Cascade Sample	source code
Delete Instance Config Sample	source code
Drop Foreign Key Constraint Delete Cascade Sample	source code
Drop Sequence Sample	source code
Enable Fine Grained Access	source code
Get Database Ddl Sample	source code
Get Instance Config Sample	source code
List Database Roles	source code
List Databases Sample	source code
List Instance Config Operations Sample	source code
List Instance Configs Sample	source code
Pg Alter Sequence Sample	source code
Pg Case Sensitivity Sample	source code
Pg Create Sequence Sample	source code
Pg Drop Sequence Sample	source code
Pg Interleaved Table Sample	source code
Pg Spanner Sample	source code
Restore Backup With Encryption Key	source code
Spanner Sample	source code
Update Database Sample	source code
Update Database With Default Leader Sample	source code
Update Instance Config Sample	source code

Troubleshooting

To get help, follow the instructions in the shared Troubleshooting document.

Transport

Cloud Spanner uses gRPC for the transport layer.

Supported Java Versions

Java 8 or above is required for using this client.

Google's Java client libraries, Google Cloud Client Libraries and Google Cloud API Libraries, follow the Oracle Java SE support roadmap (see the Oracle Java SE Product Releases section).

For new development

In general, new feature development occurs with support for the lowest Java LTS version covered by Oracle's Premier Support (which typically lasts 5 years from initial General Availability). If the minimum required JVM for a given library is changed, it is accompanied by a semver major release.

Java 11 and (in September 2021) Java 17 are the best choices for new development.

Keeping production systems current

Google tests its client libraries with all current LTS versions covered by Oracle's Extended Support (which typically lasts 8 years from initial General Availability).

Legacy support

Google's client libraries support legacy versions of Java runtimes with long term stable libraries that don't receive feature updates on a best efforts basis as it may not be possible to backport all patches.

Google provides updates on a best efforts basis to apps that continue to use Java 7, though apps might need to upgrade to current versions of the library that supports their JVM.

Where to find specific information

The latest versions and the supported Java versions are identified on the individual GitHub repository github.com/GoogleAPIs/java-SERVICENAME and on google-cloud-java.

Versioning

This library follows Semantic Versioning.

Contributing

Contributions to this library are always welcome and highly encouraged.

See CONTRIBUTING for more information how to get started.

Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms. See Code of Conduct for more information.

License

Apache 2.0 - See LICENSE for more information.

CI Status

Java Version	Status
Java 8
Java 8 OSX
Java 8 Windows
Java 11

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