com.google.cloud.bigquery.storage.v1beta2.BigQueryReadClient Maven / Gradle / Ivy
/*
* Copyright 2020 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.cloud.bigquery.storage.v1beta2;
import com.google.api.core.BetaApi;
import com.google.api.gax.core.BackgroundResource;
import com.google.api.gax.rpc.ServerStreamingCallable;
import com.google.api.gax.rpc.UnaryCallable;
import com.google.cloud.bigquery.storage.v1beta2.stub.EnhancedBigQueryReadStub;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
/**
* Service Description: BigQuery Read API.
*
* The Read API can be used to read data from BigQuery.
*
*
This class provides the ability to make remote calls to the backing service through method
* calls that map to API methods. Sample code to get started:
*
*
*
* try (BigQueryReadClient BigQueryReadClient = BigQueryReadClient.create()) {
* String parent = "";
* ReadSession readSession = ReadSession.newBuilder().build();
* int maxStreamCount = 0;
* ReadSession response = BigQueryReadClient.createReadSession(parent, readSession, maxStreamCount);
* }
*
*
*
* Note: close() needs to be called on the BigQueryReadClient object to clean up resources such
* as threads. In the example above, try-with-resources is used, which automatically calls close().
*
*
The surface of this class includes several types of Java methods for each of the API's
* methods:
*
*
* - A "flattened" method. With this type of method, the fields of the request type have been
* converted into function parameters. It may be the case that not all fields are available as
* parameters, and not every API method will have a flattened method entry point.
*
- A "request object" method. This type of method only takes one parameter, a request object,
* which must be constructed before the call. Not every API method will have a request object
* method.
*
- A "callable" method. This type of method takes no parameters and returns an immutable API
* callable object, which can be used to initiate calls to the service.
*
*
* See the individual methods for example code.
*
*
Many parameters require resource names to be formatted in a particular way. To assist with
* these names, this class includes a format method for each type of name, and additionally a parse
* method to extract the individual identifiers contained within names that are returned.
*
*
This class can be customized by passing in a custom instance of BigQueryReadSettings to
* create(). For example:
*
*
To customize credentials:
*
*
*
* BigQueryReadSettings BigQueryReadSettings =
* BigQueryReadSettings.newBuilder()
* .setCredentialsProvider(FixedCredentialsProvider.create(myCredentials))
* .build();
* BigQueryReadClient BigQueryReadClient =
* BigQueryReadClient.create(BigQueryReadSettings);
*
*
*
* To customize the endpoint:
*
*
*
* BigQueryReadSettings BigQueryReadSettings =
* BigQueryReadSettings.newBuilder().setEndpoint(myEndpoint).build();
* BigQueryReadClient BigQueryReadClient =
* BigQueryReadClient.create(BigQueryReadSettings);
*
*
*/
@BetaApi
public class BigQueryReadClient implements BackgroundResource {
private final BigQueryReadSettings settings;
private final EnhancedBigQueryReadStub stub;
/** Constructs an instance of BigQueryReadClient with default settings. */
public static final BigQueryReadClient create() throws IOException {
return create(BigQueryReadSettings.newBuilder().build());
}
/**
* Constructs an instance of BigQueryReadClient, using the given settings. The channels are
* created based on the settings passed in, or defaults for any settings that are not set.
*/
public static final BigQueryReadClient create(BigQueryReadSettings settings) throws IOException {
return new BigQueryReadClient(settings);
}
/**
* Constructs an instance of BigQueryReadClient, using the given stub for making calls. This is
* for advanced usage - prefer to use BigQueryReadSettings}.
*/
@BetaApi("A restructuring of stub classes is planned, so this may break in the future")
public static final BigQueryReadClient create(EnhancedBigQueryReadStub stub) {
return new BigQueryReadClient(stub);
}
/**
* Constructs an instance of BigQueryReadClient, using the given settings. This is protected so
* that it is easy to make a subclass, but otherwise, the static factory methods should be
* preferred.
*/
protected BigQueryReadClient(BigQueryReadSettings settings) throws IOException {
this.settings = settings;
this.stub = EnhancedBigQueryReadStub.create(settings.getTypedStubSettings());
}
@BetaApi("A restructuring of stub classes is planned, so this may break in the future")
protected BigQueryReadClient(EnhancedBigQueryReadStub stub) {
this.settings = null;
this.stub = stub;
}
public final BigQueryReadSettings getSettings() {
return settings;
}
@BetaApi("A restructuring of stub classes is planned, so this may break in the future")
public EnhancedBigQueryReadStub getStub() {
return stub;
}
/**
* Creates a new read session. A read session divides the contents of a BigQuery table into one or
* more streams, which can then be used to read data from the table. The read session also
* specifies properties of the data to be read, such as a list of columns or a push-down filter
* describing the rows to be returned.
*
* A particular row can be read by at most one stream. When the caller has reached the end of
* each stream in the session, then all the data in the table has been read.
*
*
Data is assigned to each stream such that roughly the same number of rows can be read from
* each stream. Because the server-side unit for assigning data is collections of rows, the API
* does not guarantee that each stream will return the same number or rows. Additionally, the
* limits are enforced based on the number of pre-filtered rows, so some filters can lead to
* lopsided assignments.
*
*
Read sessions automatically expire 24 hours after they are created and do not require manual
* clean-up by the caller.
*
*
Sample code:
*
*
* try (BigQueryReadClient BigQueryReadClient = BigQueryReadClient.create()) {
* String parent = "";
* ReadSession readSession = ReadSession.newBuilder().build();
* int maxStreamCount = 0;
* ReadSession response = BigQueryReadClient.createReadSession(parent, readSession, maxStreamCount);
* }
*
*
* @param parent Required. The request project that owns the session, in the form of
* `projects/{project_id}`.
* @param readSession Required. Session to be created.
* @param maxStreamCount Max initial number of streams. If unset or zero, the server will provide
* a value of streams so as to produce reasonable throughput. Must be non-negative. The number
* of streams may be lower than the requested number, depending on the amount parallelism that
* is reasonable for the table. Error will be returned if the max count is greater than the
* current system max limit of 1,000.
* Streams must be read starting from offset 0.
* @throws com.google.api.gax.rpc.ApiException if the remote call fails
*/
public final ReadSession createReadSession(
String parent, ReadSession readSession, int maxStreamCount) {
CreateReadSessionRequest request =
CreateReadSessionRequest.newBuilder()
.setParent(parent)
.setReadSession(readSession)
.setMaxStreamCount(maxStreamCount)
.build();
return createReadSession(request);
}
/**
* Creates a new read session. A read session divides the contents of a BigQuery table into one or
* more streams, which can then be used to read data from the table. The read session also
* specifies properties of the data to be read, such as a list of columns or a push-down filter
* describing the rows to be returned.
*
*
A particular row can be read by at most one stream. When the caller has reached the end of
* each stream in the session, then all the data in the table has been read.
*
*
Data is assigned to each stream such that roughly the same number of rows can be read from
* each stream. Because the server-side unit for assigning data is collections of rows, the API
* does not guarantee that each stream will return the same number or rows. Additionally, the
* limits are enforced based on the number of pre-filtered rows, so some filters can lead to
* lopsided assignments.
*
*
Read sessions automatically expire 24 hours after they are created and do not require manual
* clean-up by the caller.
*
*
Sample code:
*
*
* try (BigQueryReadClient BigQueryReadClient = BigQueryReadClient.create()) {
* CreateReadSessionRequest request = CreateReadSessionRequest.newBuilder().build();
* ReadSession response = BigQueryReadClient.createReadSession(request);
* }
*
*
* @param request The request object containing all of the parameters for the API call.
* @throws com.google.api.gax.rpc.ApiException if the remote call fails
*/
public final ReadSession createReadSession(CreateReadSessionRequest request) {
return createReadSessionCallable().call(request);
}
/**
* Creates a new read session. A read session divides the contents of a BigQuery table into one or
* more streams, which can then be used to read data from the table. The read session also
* specifies properties of the data to be read, such as a list of columns or a push-down filter
* describing the rows to be returned.
*
* A particular row can be read by at most one stream. When the caller has reached the end of
* each stream in the session, then all the data in the table has been read.
*
*
Data is assigned to each stream such that roughly the same number of rows can be read from
* each stream. Because the server-side unit for assigning data is collections of rows, the API
* does not guarantee that each stream will return the same number or rows. Additionally, the
* limits are enforced based on the number of pre-filtered rows, so some filters can lead to
* lopsided assignments.
*
*
Read sessions automatically expire 24 hours after they are created and do not require manual
* clean-up by the caller.
*
*
Sample code:
*
*
* try (BigQueryReadClient bigQueryReadClient = BigQueryReadClient.create()) {
* CreateReadSessionRequest request = CreateReadSessionRequest.newBuilder().build();
* ApiFuture<ReadSession> future = BigQueryReadClient.createReadSessionCallable().futureCall(request);
* // Do something
* ReadSession response = future.get();
* }
*
*/
public final UnaryCallable createReadSessionCallable() {
return stub.createReadSessionCallable();
}
/**
* Reads rows from the stream in the format prescribed by the ReadSession. Each response contains
* one or more table rows, up to a maximum of 100 MiB per response; read requests which attempt to
* read individual rows larger than 100 MiB will fail.
*
* Each request also returns a set of stream statistics reflecting the current state of the
* stream.
*
*
Sample code:
*
*
* try (BigQueryReadClient bigQueryReadClient = BigQueryReadClient.create()) {
* ReadRowsRequest request = ReadRowsRequest.newBuilder().build();
*
* ServerStream<ReadRowsResponse> stream = bigQueryReadClient.readRowsCallable().call(request);
* for (ReadRowsResponse response : stream) {
* // Do something when receive a response
* }
* }
*
*/
public final ServerStreamingCallable readRowsCallable() {
return stub.readRowsCallable();
}
/**
* Splits a given `ReadStream` into two `ReadStream` objects. These `ReadStream` objects are
* referred to as the primary and the residual streams of the split. The original `ReadStream` can
* still be read from in the same manner as before. Both of the returned `ReadStream` objects can
* also be read from, and the rows returned by both child streams will be the same as the rows
* read from the original stream.
*
* Moreover, the two child streams will be allocated back-to-back in the original `ReadStream`.
* Concretely, it is guaranteed that for streams original, primary, and residual, that
* original[0-j] = primary[0-j] and original[j-n] = residual[0-m] once the streams have been read
* to completion.
*
*
Sample code:
*
*
* try (BigQueryReadClient bigQueryReadClient = BigQueryReadClient.create()) {
* SplitReadStreamRequest request = SplitReadStreamRequest.newBuilder().build();
* SplitReadStreamResponse response = bigQueryReadClient.splitReadStream(request);
* }
*
*
* @param request The request object containing all of the parameters for the API call.
* @throws com.google.api.gax.rpc.ApiException if the remote call fails
*/
public final SplitReadStreamResponse splitReadStream(SplitReadStreamRequest request) {
return splitReadStreamCallable().call(request);
}
/**
* Splits a given `ReadStream` into two `ReadStream` objects. These `ReadStream` objects are
* referred to as the primary and the residual streams of the split. The original `ReadStream` can
* still be read from in the same manner as before. Both of the returned `ReadStream` objects can
* also be read from, and the rows returned by both child streams will be the same as the rows
* read from the original stream.
*
* Moreover, the two child streams will be allocated back-to-back in the original `ReadStream`.
* Concretely, it is guaranteed that for streams original, primary, and residual, that
* original[0-j] = primary[0-j] and original[j-n] = residual[0-m] once the streams have been read
* to completion.
*
*
Sample code:
*
*
* try (BigQueryReadClient bigQueryReadClient = BigQueryReadClient.create()) {
* SplitReadStreamRequest request = SplitReadStreamRequest.newBuilder().build();
* ApiFuture<SplitReadStreamResponse> future = bigQueryReadClient.splitReadStreamCallable().futureCall(request);
* // Do something
* SplitReadStreamResponse response = future.get();
* }
*
*/
public final UnaryCallable
splitReadStreamCallable() {
return stub.splitReadStreamCallable();
}
@Override
public final void close() {
stub.close();
}
@Override
public void shutdown() {
stub.shutdown();
}
@Override
public boolean isShutdown() {
return stub.isShutdown();
}
@Override
public boolean isTerminated() {
return stub.isTerminated();
}
@Override
public void shutdownNow() {
stub.shutdownNow();
}
@Override
public boolean awaitTermination(long duration, TimeUnit unit) throws InterruptedException {
return stub.awaitTermination(duration, unit);
}
}