Quickstart

The following shows the code that you'll run in the google/cloud/bigquery/quickstart/ directory, which should give you a taste of the Cloud BigQuery C++ client library API.

#include "google/cloud/bigquery/storage/v1/bigquery_read_client.h"
#include <iostream>
 
namespace {
void ProcessRowsInAvroFormat(
    ::google::cloud::bigquery::storage::v1::AvroSchema const&,
    ::google::cloud::bigquery::storage::v1::AvroRows const&) {
  // Code to deserialize avro rows should be added here.
}
}  // namespace
 
int main(int argc, char* argv[]) try {
  if (argc != 3) {
    std::cerr << "Usage: " << argv[0] << " <project-id> <table-name>\n";
    return 1;
  }
 
  // project_name should be in the format "projects/<your-gcp-project>"
  std::string const project_name = "projects/" + std::string(argv[1]);
  // table_name should be in the format:
  // "projects/<project-table-resides-in>/datasets/<dataset-table_resides-in>/tables/<table
  // name>" The project values in project_name and table_name do not have to be
  // identical.
  std::string const table_name = argv[2];
 
  // Create a namespace alias to make the code easier to read.
  namespace bigquery_storage = ::google::cloud::bigquery_storage_v1;
  constexpr int kMaxReadStreams = 1;
  // Create the ReadSession.
  auto client = bigquery_storage::BigQueryReadClient(
      bigquery_storage::MakeBigQueryReadConnection());
  ::google::cloud::bigquery::storage::v1::ReadSession read_session;
  read_session.set_data_format(
      google::cloud::bigquery::storage::v1::DataFormat::AVRO);
  read_session.set_table(table_name);
  auto session =
      client.CreateReadSession(project_name, read_session, kMaxReadStreams);
  if (!session) throw std::move(session).status();
 
  // Read rows from the ReadSession.
  constexpr int kRowOffset = 0;
  auto read_rows = client.ReadRows(session->streams(0).name(), kRowOffset);
 
  std::int64_t num_rows = 0;
  for (auto const& row : read_rows) {
    if (row.ok()) {
      num_rows += row->row_count();
      ProcessRowsInAvroFormat(session->avro_schema(), row->avro_rows());
    }
  }
 
  std::cout << num_rows << " rows read from table: " << table_name << "\n";
  return 0;
} catch (google::cloud::Status const& status) {
  std::cerr << "google::cloud::Status thrown: " << status << "\n";
  return 1;
}

Main classes

This library offers multiple *Client classes, which are listed below. Each one of these classes exposes all the RPCs for a gRPC service as member functions of the class. This library groups multiple gRPC services because they are part of the same product or are often used together. A typical example may be the administrative and data plane operations for a single product.

The library also has other classes that provide helpers, configuration parameters, and infrastructure to mock the *Client classes when testing your application.

Next Steps

Error Handling - describes how the library reports errors.
How to Override the Default Endpoint - describes how to override the default endpoint.
How to Override the Authentication Credentials - describes how to change the authentication credentials used by the library.
Override Retry, Backoff, and Idempotency Policies - describes how to change the default retry policies.
Environment Variables - describes environment variables that can configure the behavior of the library.
Testing your Cloud BigQueryRead application with googlemock

Table of Contents

Quickstart

Main classes

Next Steps