README.md

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>25.4.0</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 BOM, add this to your dependencies:

<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-spanner</artifactId>
  <version>6.25.6</version>
</dependency>

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

implementation platform('com.google.cloud:libraries-bom:26.0.0')

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:6.25.7'

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

libraryDependencies += "com.google.cloud" % "google-cloud-spanner" % "6.25.7"

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 SDK 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, schemas, SQL (ANSI 2011 with extensions), and automatic, synchronous replication for high availability.

Be sure to activate the Cloud Spanner API on the Developer's Console to use 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.

OpenCensus Metrics

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 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.
• library_version: the version of the library that you're using.

Note: RPC level metrics can be gleaned from gRPC’s metrics, which are prefixed with grpc.io/client/.

Available client-side metrics:

• cloud.google.com/java/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.

• cloud.google.com/java/spanner/max_allowed_sessions: This shows the maximum number of sessions allowed.

• cloud.google.com/java/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.

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

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

• cloud.google.com/java/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.

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

• cloud.google.com/java/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.

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'

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();

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.

Samples

Samples are in the samples/ directory.

Sample	Source Code	Try it
Database Operations	source code
Instance Operations	source code
Native Image Spanner Sample	source code
Add Json Column Sample	source code
Add Numeric Column 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
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 Example	source code
Create Instance With Processing Units Example	source code
Custom Timeout And Retry Settings Example	source code
Get Commit Stats Sample	source code
Get Database Ddl Sample	source code
Get Instance Config Sample	source code
List Databases Sample	source code
List Instance Configs 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 Interleaved Table Sample	source code
Pg Partitioned Dml Sample	source code
Pg Query With Numeric Parameter Sample	source code
Pg Spanner Sample	source code
Query Information Schema Database Options Sample	source code
Query With Json Parameter Sample	source code
Query With Numeric Parameter Sample	source code
Quickstart Sample	source code
Restore Backup With Encryption Key	source code
Spanner Sample	source code
Statement Timeout Example	source code
Tag Sample	source code
Tracing Sample	source code
Update Database With Default Leader Sample	source code
Update Json Data Sample	source code
Update Numeric Data 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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