Gepufferte Einträge anhängen

JSON-Stream-Writer verwenden, um Einträge im Zwischenspeichermodus anzuhängen

Codebeispiel

Java

Bevor Sie dieses Beispiel anwenden, folgen Sie den Schritten zur Einrichtung von Java in der BigQuery-Kurzanleitung zur Verwendung von Clientbibliotheken. Weitere Angaben finden Sie in der Referenzdokumentation zur BigQuery Java API.

Richten Sie zur Authentifizierung bei BigQuery die Standardanmeldedaten für Anwendungen ein. Weitere Informationen finden Sie unter Authentifizierung für Clientbibliotheken einrichten.

import com.google.api.core.ApiFuture;
import com.google.api.gax.retrying.RetrySettings;
import com.google.cloud.bigquery.storage.v1.AppendRowsResponse;
import com.google.cloud.bigquery.storage.v1.BigQueryWriteClient;
import com.google.cloud.bigquery.storage.v1.CreateWriteStreamRequest;
import com.google.cloud.bigquery.storage.v1.FinalizeWriteStreamRequest;
import com.google.cloud.bigquery.storage.v1.FlushRowsRequest;
import com.google.cloud.bigquery.storage.v1.FlushRowsResponse;
import com.google.cloud.bigquery.storage.v1.JsonStreamWriter;
import com.google.cloud.bigquery.storage.v1.TableName;
import com.google.cloud.bigquery.storage.v1.WriteStream;
import com.google.protobuf.Descriptors.DescriptorValidationException;
import com.google.protobuf.Int64Value;
import java.io.IOException;
import java.util.concurrent.ExecutionException;
import org.json.JSONArray;
import org.json.JSONObject;
import org.threeten.bp.Duration;

public class WriteBufferedStream {

  public static void runWriteBufferedStream()
      throws DescriptorValidationException, InterruptedException, IOException {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "MY_PROJECT_ID";
    String datasetName = "MY_DATASET_NAME";
    String tableName = "MY_TABLE_NAME";

    writeBufferedStream(projectId, datasetName, tableName);
  }

  public static void writeBufferedStream(String projectId, String datasetName, String tableName)
      throws DescriptorValidationException, InterruptedException, IOException {
    try (BigQueryWriteClient client = BigQueryWriteClient.create()) {
      // Initialize a write stream for the specified table.
      // For more information on WriteStream.Type, see:
      // https://googleapis.dev/java/google-cloud-bigquerystorage/latest/com/google/cloud/bigquery/storage/v1/WriteStream.Type.html
      WriteStream stream = WriteStream.newBuilder().setType(WriteStream.Type.BUFFERED).build();
      TableName parentTable = TableName.of(projectId, datasetName, tableName);
      CreateWriteStreamRequest createWriteStreamRequest =
          CreateWriteStreamRequest.newBuilder()
              .setParent(parentTable.toString())
              .setWriteStream(stream)
              .build();
      WriteStream writeStream = client.createWriteStream(createWriteStreamRequest);

      // Configure in-stream automatic retry settings.
      // Error codes that are immediately retried:
      // * ABORTED, UNAVAILABLE, CANCELLED, INTERNAL, DEADLINE_EXCEEDED
      // Error codes that are retried with exponential backoff:
      // * RESOURCE_EXHAUSTED
      RetrySettings retrySettings =
          RetrySettings.newBuilder()
              .setInitialRetryDelay(Duration.ofMillis(500))
              .setRetryDelayMultiplier(1.1)
              .setMaxAttempts(5)
              .setMaxRetryDelay(Duration.ofMinutes(1))
              .build();

      // Use the JSON stream writer to send records in JSON format.
      // For more information about JsonStreamWriter, see:
      // https://cloud.google.com/java/docs/reference/google-cloud-bigquerystorage/latest/com.google.cloud.bigquery.storage.v1.JsonStreamWriter
      try (JsonStreamWriter writer =
          JsonStreamWriter.newBuilder(writeStream.getName(), writeStream.getTableSchema())
              .setRetrySettings(retrySettings)
              .build()) {
        // Write two batches to the stream, each with 10 JSON records.
        for (int i = 0; i < 2; i++) {
          JSONArray jsonArr = new JSONArray();
          for (int j = 0; j < 10; j++) {
            // Create a JSON object that is compatible with the table schema.
            JSONObject record = new JSONObject();
            record.put("col1", String.format("buffered-record %03d", i));
            jsonArr.put(record);
          }
          ApiFuture<AppendRowsResponse> future = writer.append(jsonArr);
          AppendRowsResponse response = future.get();
        }
        // Flush the buffer.
        FlushRowsRequest flushRowsRequest =
            FlushRowsRequest.newBuilder()
                .setWriteStream(writeStream.getName())
                .setOffset(Int64Value.of(10 * 2 - 1)) // Advance the cursor to the latest record.
                .build();
        FlushRowsResponse flushRowsResponse = client.flushRows(flushRowsRequest);
        // You can continue to write to the stream after flushing the buffer.
      }
      // Finalize the stream after use.
      FinalizeWriteStreamRequest finalizeWriteStreamRequest =
          FinalizeWriteStreamRequest.newBuilder().setName(writeStream.getName()).build();
      client.finalizeWriteStream(finalizeWriteStreamRequest);
      System.out.println("Appended and committed records successfully.");
    } catch (ExecutionException e) {
      // If the wrapped exception is a StatusRuntimeException, check the state of the operation.
      // If the state is INTERNAL, CANCELLED, or ABORTED, you can retry. For more information, see:
      // https://grpc.github.io/grpc-java/javadoc/io/grpc/StatusRuntimeException.html
      System.out.println(e);
    }
  }
}

Nächste Schritte

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