Trasmetti il flusso di dati utilizzando l'API Storage Write
Questo documento descrive come utilizzare l'API BigQuery Storage Write per trasmettere dati in BigQuery.
Negli scenari di elaborazione in modalità flusso, i dati arrivano continuamente e dovrebbero essere disponibili per le letture con una latenza minima. Se utilizzi l'API BigQuery Storage Write per il flusso di lavoro in modalità flusso, considera le garanzie di cui hai bisogno:
- Se l'applicazione ha bisogno solo di una semantica at-least-once, utilizza il stream predefinito.
- Se hai bisogno della semantica "exactly-once", crea uno o più flussi in
tipo impegnato e utilizza gli offset del flusso per garantire le scritture "exactly-once".
Nel tipo di commit, i dati scritti nel flusso sono disponibili per la query non appena il server conferma la richiesta di scrittura. Anche il flusso predefinito utilizza
il tipo impegnato, ma non fornisce garanzie "exactly-once".
Usa lo stream predefinito per la semantica "at almeno una volta"
Se l'applicazione accetta la possibilità che nella tabella di destinazione vengano visualizzati record duplicati, ti consigliamo di utilizzare il flusso predefinito per gli scenari di flussi.
Il seguente codice mostra come scrivere dati nello stream predefinito:
Java
Per scoprire come installare e utilizzare la libreria client per BigQuery, consulta Librerie client di BigQuery.
Per saperne di più, consulta la documentazione di riferimento dell'API BigQuery Java.
Per eseguire l'autenticazione in BigQuery, configura Credenziali predefinite dell'applicazione.
Per maggiori informazioni, consulta
Configurare l'autenticazione per le librerie client.
import com.google.api.core.ApiFuture;
import com.google.api.core.ApiFutureCallback;
import com.google.api.core.ApiFutures;
import com.google.api.gax.core.FixedExecutorProvider;
import com.google.api.gax.retrying.RetrySettings;
import com.google.cloud.bigquery.BigQuery;
import com.google.cloud.bigquery.BigQueryOptions;
import com.google.cloud.bigquery.QueryJobConfiguration;
import com.google.cloud.bigquery.TableResult;
import com.google.cloud.bigquery.storage.v1.AppendRowsRequest;
import com.google.cloud.bigquery.storage.v1.AppendRowsResponse;
import com.google.cloud.bigquery.storage.v1.BigQueryWriteClient;
import com.google.cloud.bigquery.storage.v1.BigQueryWriteSettings;
import com.google.cloud.bigquery.storage.v1.Exceptions;
import com.google.cloud.bigquery.storage.v1.Exceptions.AppendSerializationError;
import com.google.cloud.bigquery.storage.v1.Exceptions.MaximumRequestCallbackWaitTimeExceededException;
import com.google.cloud.bigquery.storage.v1.Exceptions.StorageException;
import com.google.cloud.bigquery.storage.v1.Exceptions.StreamWriterClosedException;
import com.google.cloud.bigquery.storage.v1.JsonStreamWriter;
import com.google.cloud.bigquery.storage.v1.TableName;
import com.google.common.util.concurrent.MoreExecutors;
import com.google.protobuf.ByteString;
import com.google.protobuf.Descriptors.DescriptorValidationException;
import java.io.IOException;
import java.util.Map;
import java.util.concurrent.Executors;
import java.util.concurrent.Phaser;
import java.util.concurrent.atomic.AtomicInteger;
import javax.annotation.concurrent.GuardedBy;
import org.json.JSONArray;
import org.json.JSONObject;
import org.threeten.bp.Duration;
public class WriteToDefaultStream {
public static void runWriteToDefaultStream()
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";
writeToDefaultStream(projectId, datasetName, tableName);
}
private static ByteString buildByteString() {
byte[] bytes = new byte[] {1, 2, 3, 4, 5};
return ByteString.copyFrom(bytes);
}
// Create a JSON object that is compatible with the table schema.
private static JSONObject buildRecord(int i, int j) {
JSONObject record = new JSONObject();
StringBuilder sbSuffix = new StringBuilder();
for (int k = 0; k < j; k++) {
sbSuffix.append(k);
}
record.put("test_string", String.format("record %03d-%03d %s", i, j, sbSuffix.toString()));
ByteString byteString = buildByteString();
record.put("test_bytes", byteString);
return record;
}
public static void writeToDefaultStream(String projectId, String datasetName, String tableName)
throws DescriptorValidationException, InterruptedException, IOException {
TableName parentTable = TableName.of(projectId, datasetName, tableName);
DataWriter writer = new DataWriter();
// One time initialization for the worker.
writer.initialize(parentTable);
// Write two batches of fake data to the stream, each with 10 JSON records. Data may be
// batched up to the maximum request size:
// https://cloud.google.com/bigquery/quotas#write-api-limits
for (int i = 0; i < 2; i++) {
JSONArray jsonArr = new JSONArray();
for (int j = 0; j < 10; j++) {
JSONObject record = buildRecord(i, j);
jsonArr.put(record);
}
writer.append(new AppendContext(jsonArr));
}
// Final cleanup for the stream during worker teardown.
writer.cleanup();
verifyExpectedRowCount(parentTable, 12);
System.out.println("Appended records successfully.");
}
private static void verifyExpectedRowCount(TableName parentTable, int expectedRowCount)
throws InterruptedException {
String queryRowCount =
"SELECT COUNT(*) FROM `"
+ parentTable.getProject()
+ "."
+ parentTable.getDataset()
+ "."
+ parentTable.getTable()
+ "`";
QueryJobConfiguration queryConfig = QueryJobConfiguration.newBuilder(queryRowCount).build();
BigQuery bigquery = BigQueryOptions.getDefaultInstance().getService();
TableResult results = bigquery.query(queryConfig);
int countRowsActual =
Integer.parseInt(results.getValues().iterator().next().get("f0_").getStringValue());
if (countRowsActual != expectedRowCount) {
throw new RuntimeException(
"Unexpected row count. Expected: " + expectedRowCount + ". Actual: " + countRowsActual);
}
}
private static class AppendContext {
JSONArray data;
AppendContext(JSONArray data) {
this.data = data;
}
}
private static class DataWriter {
private static final int MAX_RECREATE_COUNT = 3;
private BigQueryWriteClient client;
// Track the number of in-flight requests to wait for all responses before shutting down.
private final Phaser inflightRequestCount = new Phaser(1);
private final Object lock = new Object();
private JsonStreamWriter streamWriter;
@GuardedBy("lock")
private RuntimeException error = null;
private AtomicInteger recreateCount = new AtomicInteger(0);
private JsonStreamWriter createStreamWriter(String tableName)
throws DescriptorValidationException, IOException, InterruptedException {
// 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. Specify the table name to write
// to the default stream.
// For more information about JsonStreamWriter, see:
// https://googleapis.dev/java/google-cloud-bigquerystorage/latest/com/google/cloud/bigquery/storage/v1/JsonStreamWriter.html
return JsonStreamWriter.newBuilder(tableName, client)
.setExecutorProvider(FixedExecutorProvider.create(Executors.newScheduledThreadPool(100)))
.setChannelProvider(
BigQueryWriteSettings.defaultGrpcTransportProviderBuilder()
.setKeepAliveTime(org.threeten.bp.Duration.ofMinutes(1))
.setKeepAliveTimeout(org.threeten.bp.Duration.ofMinutes(1))
.setKeepAliveWithoutCalls(true)
.setChannelsPerCpu(2)
.build())
.setEnableConnectionPool(true)
// If value is missing in json and there is a default value configured on bigquery
// column, apply the default value to the missing value field.
.setDefaultMissingValueInterpretation(
AppendRowsRequest.MissingValueInterpretation.DEFAULT_VALUE)
.setRetrySettings(retrySettings)
.build();
}
public void initialize(TableName parentTable)
throws DescriptorValidationException, IOException, InterruptedException {
// Initialize client without settings, internally within stream writer a new client will be
// created with full settings.
client = BigQueryWriteClient.create();
streamWriter = createStreamWriter(parentTable.toString());
}
public void append(AppendContext appendContext)
throws DescriptorValidationException, IOException, InterruptedException {
synchronized (this.lock) {
if (!streamWriter.isUserClosed()
&& streamWriter.isClosed()
&& recreateCount.getAndIncrement() < MAX_RECREATE_COUNT) {
streamWriter = createStreamWriter(streamWriter.getStreamName());
this.error = null;
}
// If earlier appends have failed, we need to reset before continuing.
if (this.error != null) {
throw this.error;
}
}
// Append asynchronously for increased throughput.
ApiFuture<AppendRowsResponse> future = streamWriter.append(appendContext.data);
ApiFutures.addCallback(
future, new AppendCompleteCallback(this, appendContext), MoreExecutors.directExecutor());
// Increase the count of in-flight requests.
inflightRequestCount.register();
}
public void cleanup() {
// Wait for all in-flight requests to complete.
inflightRequestCount.arriveAndAwaitAdvance();
client.close();
// Close the connection to the server.
streamWriter.close();
// Verify that no error occurred in the stream.
synchronized (this.lock) {
if (this.error != null) {
throw this.error;
}
}
}
static class AppendCompleteCallback implements ApiFutureCallback<AppendRowsResponse> {
private final DataWriter parent;
private final AppendContext appendContext;
public AppendCompleteCallback(DataWriter parent, AppendContext appendContext) {
this.parent = parent;
this.appendContext = appendContext;
}
public void onSuccess(AppendRowsResponse response) {
System.out.format("Append success\n");
this.parent.recreateCount.set(0);
done();
}
public void onFailure(Throwable throwable) {
if (throwable instanceof AppendSerializationError) {
AppendSerializationError ase = (AppendSerializationError) throwable;
Map<Integer, String> rowIndexToErrorMessage = ase.getRowIndexToErrorMessage();
if (rowIndexToErrorMessage.size() > 0) {
// Omit the faulty rows
JSONArray dataNew = new JSONArray();
for (int i = 0; i < appendContext.data.length(); i++) {
if (!rowIndexToErrorMessage.containsKey(i)) {
dataNew.put(appendContext.data.get(i));
} else {
// process faulty rows by placing them on a dead-letter-queue, for instance
}
}
// Retry the remaining valid rows, but using a separate thread to
// avoid potentially blocking while we are in a callback.
if (dataNew.length() > 0) {
try {
this.parent.append(new AppendContext(dataNew));
} catch (DescriptorValidationException e) {
throw new RuntimeException(e);
} catch (IOException e) {
throw new RuntimeException(e);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
// Mark the existing attempt as done since we got a response for it
done();
return;
}
}
boolean resendRequest = false;
if (throwable instanceof MaximumRequestCallbackWaitTimeExceededException) {
resendRequest = true;
} else if (throwable instanceof StreamWriterClosedException) {
if (!parent.streamWriter.isUserClosed()) {
resendRequest = true;
}
}
if (resendRequest) {
// Retry this request.
try {
this.parent.append(new AppendContext(appendContext.data));
} catch (DescriptorValidationException e) {
throw new RuntimeException(e);
} catch (IOException e) {
throw new RuntimeException(e);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
// Mark the existing attempt as done since we got a response for it
done();
return;
}
synchronized (this.parent.lock) {
if (this.parent.error == null) {
StorageException storageException = Exceptions.toStorageException(throwable);
this.parent.error =
(storageException != null) ? storageException : new RuntimeException(throwable);
}
}
done();
}
private void done() {
// Reduce the count of in-flight requests.
this.parent.inflightRequestCount.arriveAndDeregister();
}
}
}
}
Utilizzare il multiplexing
Puoi abilitare il multiplexing a livello di autore dello stream solo per lo stream predefinito. Per abilitare il multiplexing in Java, chiama il metodo setEnableConnectionPool quando crei un oggetto StreamWriter o JsonStreamWriter:
// One possible way for constructing StreamWriter
StreamWriter.newBuilder(streamName)
.setWriterSchema(protoSchema)
.setEnableConnectionPool(true)
.build();
// One possible way for constructing JsonStreamWriter
JsonStreamWriter.newBuilder(tableName, bigqueryClient)
.setEnableConnectionPool(true)
.build();
Per attivare il multiplexing in Go, consulta Condivisione della connessione (multiplexing).
Utilizza il tipo impegnato per la semantica "exactly-once"
Se hai bisogno di scrivere la semantica "exactly-once", crea un flusso di scrittura nel tipo impegnato. Nel tipo di commit, i record sono disponibili per la query non appena il client riceve la conferma dal backend.
Il tipo impegnato offre la pubblicazione "exactly-once" all'interno di uno stream tramite l'uso degli
offset dei record. Utilizzando gli offset dei record, l'applicazione specifica l'offset di aggiunta successivo in ogni chiamata a AppendRows. L'operazione di scrittura viene eseguita solo se il valore di offset corrisponde all'offset di aggiunta successivo. Per saperne di più, consulta Gestire gli offset del flusso per ottenere la semantica "exactly-once".
Se non fornisci un offset, i record vengono aggiunti alla fine attuale del flusso. In questo caso, se una richiesta di aggiunta restituisce un errore, un nuovo tentativo potrebbe comportare la visualizzazione del record più volte nel flusso.
Per utilizzare il tipo impegnato, segui questi passaggi:
- Chiama
CreateWriteStream per creare uno o più stream di tipo impegnato.
- Per ogni flusso, chiama
AppendRows in un loop per scrivere batch di record.
- Chiama
FinalizeWriteStream per ogni stream per rilasciare lo stream. Dopo aver chiamato questo metodo, non puoi scrivere altre righe nel flusso. Questo passaggio è facoltativo nel tipo di commit, ma consente di evitare il superamento del limite dei flussi attivi. Per maggiori informazioni, consulta
Limitare la frequenza di creazione degli stream.
Non puoi eliminare uno stream in modo esplicito. Gli stream seguono la durata (TTL) definita dal sistema:
- Se non c'è traffico, uno stream impegnato ha un TTL di tre giorni.
- Per impostazione predefinita, uno stream con buffer ha un TTL di sette giorni se non c'è traffico.
Il codice seguente mostra come utilizzare il tipo impegnato:
Java
Per scoprire come installare e utilizzare la libreria client per BigQuery, consulta Librerie client di BigQuery.
Per saperne di più, consulta la documentazione di riferimento dell'API BigQuery Java.
Per eseguire l'autenticazione in BigQuery, configura Credenziali predefinite dell'applicazione.
Per maggiori informazioni, consulta
Configurare l'autenticazione per le librerie client.
import com.google.api.core.ApiFuture;
import com.google.api.core.ApiFutureCallback;
import com.google.api.core.ApiFutures;
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.Exceptions;
import com.google.cloud.bigquery.storage.v1.Exceptions.StorageException;
import com.google.cloud.bigquery.storage.v1.FinalizeWriteStreamResponse;
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.common.util.concurrent.MoreExecutors;
import com.google.protobuf.Descriptors.DescriptorValidationException;
import java.io.IOException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Phaser;
import javax.annotation.concurrent.GuardedBy;
import org.json.JSONArray;
import org.json.JSONObject;
import org.threeten.bp.Duration;
public class WriteCommittedStream {
public static void runWriteCommittedStream()
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";
writeCommittedStream(projectId, datasetName, tableName);
}
public static void writeCommittedStream(String projectId, String datasetName, String tableName)
throws DescriptorValidationException, InterruptedException, IOException {
BigQueryWriteClient client = BigQueryWriteClient.create();
TableName parentTable = TableName.of(projectId, datasetName, tableName);
DataWriter writer = new DataWriter();
// One time initialization.
writer.initialize(parentTable, client);
try {
// Write two batches of fake data to the stream, each with 10 JSON records. Data may be
// batched up to the maximum request size:
// https://cloud.google.com/bigquery/quotas#write-api-limits
long offset = 0;
for (int i = 0; i < 2; i++) {
// Create a JSON object that is compatible with the table schema.
JSONArray jsonArr = new JSONArray();
for (int j = 0; j < 10; j++) {
JSONObject record = new JSONObject();
record.put("col1", String.format("batch-record %03d-%03d", i, j));
jsonArr.put(record);
}
writer.append(jsonArr, offset);
offset += jsonArr.length();
}
} 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("Failed to append records. \n" + e);
}
// Final cleanup for the stream.
writer.cleanup(client);
System.out.println("Appended records successfully.");
}
// A simple wrapper object showing how the stateful stream writer should be used.
private static class DataWriter {
private JsonStreamWriter streamWriter;
// Track the number of in-flight requests to wait for all responses before shutting down.
private final Phaser inflightRequestCount = new Phaser(1);
private final Object lock = new Object();
@GuardedBy("lock")
private RuntimeException error = null;
void initialize(TableName parentTable, BigQueryWriteClient client)
throws IOException, DescriptorValidationException, InterruptedException {
// 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.COMMITTED).build();
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://googleapis.dev/java/google-cloud-bigquerystorage/latest/com/google/cloud/bigquery/storage/v1/JsonStreamWriter.html
streamWriter =
JsonStreamWriter.newBuilder(writeStream.getName(), writeStream.getTableSchema(), client)
.setRetrySettings(retrySettings)
.build();
}
public void append(JSONArray data, long offset)
throws DescriptorValidationException, IOException, ExecutionException {
synchronized (this.lock) {
// If earlier appends have failed, we need to reset before continuing.
if (this.error != null) {
throw this.error;
}
}
// Append asynchronously for increased throughput.
ApiFuture<AppendRowsResponse> future = streamWriter.append(data, offset);
ApiFutures.addCallback(
future, new DataWriter.AppendCompleteCallback(this), MoreExecutors.directExecutor());
// Increase the count of in-flight requests.
inflightRequestCount.register();
}
public void cleanup(BigQueryWriteClient client) {
// Wait for all in-flight requests to complete.
inflightRequestCount.arriveAndAwaitAdvance();
// Close the connection to the server.
streamWriter.close();
// Verify that no error occurred in the stream.
synchronized (this.lock) {
if (this.error != null) {
throw this.error;
}
}
// Finalize the stream.
FinalizeWriteStreamResponse finalizeResponse =
client.finalizeWriteStream(streamWriter.getStreamName());
System.out.println("Rows written: " + finalizeResponse.getRowCount());
}
public String getStreamName() {
return streamWriter.getStreamName();
}
static class AppendCompleteCallback implements ApiFutureCallback<AppendRowsResponse> {
private final DataWriter parent;
public AppendCompleteCallback(DataWriter parent) {
this.parent = parent;
}
public void onSuccess(AppendRowsResponse response) {
System.out.format("Append %d success\n", response.getAppendResult().getOffset().getValue());
done();
}
public void onFailure(Throwable throwable) {
synchronized (this.parent.lock) {
if (this.parent.error == null) {
StorageException storageException = Exceptions.toStorageException(throwable);
this.parent.error =
(storageException != null) ? storageException : new RuntimeException(throwable);
}
}
System.out.format("Error: %s\n", throwable.toString());
done();
}
private void done() {
// Reduce the count of in-flight requests.
this.parent.inflightRequestCount.arriveAndDeregister();
}
}
}
}
