Class BaseBigQueryReadClient (3.8.0)

GitHub RepositoryProduct Reference

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:


 // This snippet has been automatically generated and should be regarded as a code template only.
 // It will require modifications to work:
 // - It may require correct/in-range values for request initialization.
 // - It may require specifying regional endpoints when creating the service client as shown in
 // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 try (BaseBigQueryReadClient baseBigQueryReadClient = BaseBigQueryReadClient.create()) {
   ProjectName parent = ProjectName.of("[PROJECT]");
   ReadSession readSession = ReadSession.newBuilder().build();
   int maxStreamCount = 940837515;
   ReadSession response =
       baseBigQueryReadClient.createReadSession(parent, readSession, maxStreamCount);
 }

Note: close() needs to be called on the BaseBigQueryReadClient object to clean up resources such as threads. In the example above, try-with-resources is used, which automatically calls close().

Methods
Method Description Method Variants

CreateReadSession

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 6 hours after they are created and do not require manual clean-up by the caller.

Request object method variants only take one parameter, a request object, which must be constructed before the call.

  • createReadSession(CreateReadSessionRequest request)

"Flattened" method variants have converted the fields of the request object into function parameters to enable multiple ways to call the same method.

  • createReadSession(ProjectName parent, ReadSession readSession, int maxStreamCount)

  • createReadSession(String parent, ReadSession readSession, int maxStreamCount)

Callable method variants take no parameters and return an immutable API callable object, which can be used to initiate calls to the service.

  • createReadSessionCallable()

ReadRows

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.

Callable method variants take no parameters and return an immutable API callable object, which can be used to initiate calls to the service.

  • readRowsCallable()

SplitReadStream

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.

Request object method variants only take one parameter, a request object, which must be constructed before the call.

  • splitReadStream(SplitReadStreamRequest request)

Callable method variants take no parameters and return an immutable API callable object, which can be used to initiate calls to the service.

  • splitReadStreamCallable()

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 BaseBigQueryReadSettings to create(). For example:

To customize credentials:


 // This snippet has been automatically generated and should be regarded as a code template only.
 // It will require modifications to work:
 // - It may require correct/in-range values for request initialization.
 // - It may require specifying regional endpoints when creating the service client as shown in
 // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 BaseBigQueryReadSettings baseBigQueryReadSettings =
     BaseBigQueryReadSettings.newBuilder()
         .setCredentialsProvider(FixedCredentialsProvider.create(myCredentials))
         .build();
 BaseBigQueryReadClient baseBigQueryReadClient =
     BaseBigQueryReadClient.create(baseBigQueryReadSettings);

To customize the endpoint:


 // This snippet has been automatically generated and should be regarded as a code template only.
 // It will require modifications to work:
 // - It may require correct/in-range values for request initialization.
 // - It may require specifying regional endpoints when creating the service client as shown in
 // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 BaseBigQueryReadSettings baseBigQueryReadSettings =
     BaseBigQueryReadSettings.newBuilder().setEndpoint(myEndpoint).build();
 BaseBigQueryReadClient baseBigQueryReadClient =
     BaseBigQueryReadClient.create(baseBigQueryReadSettings);

Please refer to the GitHub repository's samples for more quickstart code snippets.

Inheritance

java.lang.Object > BaseBigQueryReadClient

Static Methods

create()

public static final BaseBigQueryReadClient create()

Constructs an instance of BaseBigQueryReadClient with default settings.

Returns
Type Description
BaseBigQueryReadClient
Exceptions
Type Description
IOException

create(BaseBigQueryReadSettings settings)

public static final BaseBigQueryReadClient create(BaseBigQueryReadSettings settings)

Constructs an instance of BaseBigQueryReadClient, using the given settings. The channels are created based on the settings passed in, or defaults for any settings that are not set.

Parameter
Name Description
settings BaseBigQueryReadSettings
Returns
Type Description
BaseBigQueryReadClient
Exceptions
Type Description
IOException

create(BigQueryReadStub stub)

public static final BaseBigQueryReadClient create(BigQueryReadStub stub)

Constructs an instance of BaseBigQueryReadClient, using the given stub for making calls. This is for advanced usage - prefer using create(BaseBigQueryReadSettings).

Parameter
Name Description
stub BigQueryReadStub
Returns
Type Description
BaseBigQueryReadClient

Constructors

BaseBigQueryReadClient(BaseBigQueryReadSettings settings)

protected BaseBigQueryReadClient(BaseBigQueryReadSettings settings)

Constructs an instance of BaseBigQueryReadClient, 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.

Parameter
Name Description
settings BaseBigQueryReadSettings

BaseBigQueryReadClient(BigQueryReadStub stub)

protected BaseBigQueryReadClient(BigQueryReadStub stub)
Parameter
Name Description
stub BigQueryReadStub

Methods

awaitTermination(long duration, TimeUnit unit)

public boolean awaitTermination(long duration, TimeUnit unit)
Parameters
Name Description
duration long
unit TimeUnit
Returns
Type Description
boolean
Exceptions
Type Description
InterruptedException

close()

public final void close()

createReadSession(CreateReadSessionRequest request)

public final ReadSession createReadSession(CreateReadSessionRequest 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 6 hours after they are created and do not require manual clean-up by the caller.

Sample code:


 // This snippet has been automatically generated and should be regarded as a code template only.
 // It will require modifications to work:
 // - It may require correct/in-range values for request initialization.
 // - It may require specifying regional endpoints when creating the service client as shown in
 // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 try (BaseBigQueryReadClient baseBigQueryReadClient = BaseBigQueryReadClient.create()) {
   CreateReadSessionRequest request =
       CreateReadSessionRequest.newBuilder()
           .setParent(ProjectName.of("[PROJECT]").toString())
           .setReadSession(ReadSession.newBuilder().build())
           .setMaxStreamCount(940837515)
           .setPreferredMinStreamCount(-1905507237)
           .build();
   ReadSession response = baseBigQueryReadClient.createReadSession(request);
 }
Parameter
Name Description
request CreateReadSessionRequest

The request object containing all of the parameters for the API call.
Returns
Type Description
ReadSession

createReadSession(ProjectName parent, ReadSession readSession, int maxStreamCount)

public final ReadSession createReadSession(ProjectName parent, ReadSession readSession, int maxStreamCount)

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 6 hours after they are created and do not require manual clean-up by the caller.

Sample code:


 // This snippet has been automatically generated and should be regarded as a code template only.
 // It will require modifications to work:
 // - It may require correct/in-range values for request initialization.
 // - It may require specifying regional endpoints when creating the service client as shown in
 // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 try (BaseBigQueryReadClient baseBigQueryReadClient = BaseBigQueryReadClient.create()) {
   ProjectName parent = ProjectName.of("[PROJECT]");
   ReadSession readSession = ReadSession.newBuilder().build();
   int maxStreamCount = 940837515;
   ReadSession response =
       baseBigQueryReadClient.createReadSession(parent, readSession, maxStreamCount);
 }
Parameters
Name Description
parent ProjectName

Required. The request project that owns the session, in the form of projects/{project_id}.
readSession ReadSession

Required. Session to be created.
maxStreamCount int

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. There is a default system max limit of 1,000.

This must be greater than or equal to preferred_min_stream_count. Typically, clients should either leave this unset to let the system to determine an upper bound OR set this a size for the maximum "units of work" it can gracefully handle.
Returns
Type Description
ReadSession

createReadSession(String parent, ReadSession readSession, int maxStreamCount)

public final ReadSession createReadSession(String parent, ReadSession readSession, int maxStreamCount)

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 6 hours after they are created and do not require manual clean-up by the caller.

Sample code:


 // This snippet has been automatically generated and should be regarded as a code template only.
 // It will require modifications to work:
 // - It may require correct/in-range values for request initialization.
 // - It may require specifying regional endpoints when creating the service client as shown in
 // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 try (BaseBigQueryReadClient baseBigQueryReadClient = BaseBigQueryReadClient.create()) {
   String parent = ProjectName.of("[PROJECT]").toString();
   ReadSession readSession = ReadSession.newBuilder().build();
   int maxStreamCount = 940837515;
   ReadSession response =
       baseBigQueryReadClient.createReadSession(parent, readSession, maxStreamCount);
 }
Parameters
Name Description
parent String

Required. The request project that owns the session, in the form of projects/{project_id}.
readSession ReadSession

Required. Session to be created.
maxStreamCount int

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. There is a default system max limit of 1,000.

This must be greater than or equal to preferred_min_stream_count. Typically, clients should either leave this unset to let the system to determine an upper bound OR set this a size for the maximum "units of work" it can gracefully handle.
Returns
Type Description
ReadSession

createReadSessionCallable()

public final UnaryCallable<CreateReadSessionRequest,ReadSession> createReadSessionCallable()

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 6 hours after they are created and do not require manual clean-up by the caller.

Sample code:


 // This snippet has been automatically generated and should be regarded as a code template only.
 // It will require modifications to work:
 // - It may require correct/in-range values for request initialization.
 // - It may require specifying regional endpoints when creating the service client as shown in
 // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 try (BaseBigQueryReadClient baseBigQueryReadClient = BaseBigQueryReadClient.create()) {
   CreateReadSessionRequest request =
       CreateReadSessionRequest.newBuilder()
           .setParent(ProjectName.of("[PROJECT]").toString())
           .setReadSession(ReadSession.newBuilder().build())
           .setMaxStreamCount(940837515)
           .setPreferredMinStreamCount(-1905507237)
           .build();
   ApiFuture<ReadSession> future =
       baseBigQueryReadClient.createReadSessionCallable().futureCall(request);
   // Do something.
   ReadSession response = future.get();
 }
Returns
Type Description
UnaryCallable<CreateReadSessionRequest,ReadSession>

getSettings()

public final BaseBigQueryReadSettings getSettings()
Returns
Type Description
BaseBigQueryReadSettings

getStub()

public BigQueryReadStub getStub()
Returns
Type Description
BigQueryReadStub

isShutdown()

public boolean isShutdown()
Returns
Type Description
boolean

isTerminated()

public boolean isTerminated()
Returns
Type Description
boolean

readRowsCallable()

public final ServerStreamingCallable<ReadRowsRequest,ReadRowsResponse> readRowsCallable()

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:


 // This snippet has been automatically generated and should be regarded as a code template only.
 // It will require modifications to work:
 // - It may require correct/in-range values for request initialization.
 // - It may require specifying regional endpoints when creating the service client as shown in
 // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 try (BaseBigQueryReadClient baseBigQueryReadClient = BaseBigQueryReadClient.create()) {
   ReadRowsRequest request =
       ReadRowsRequest.newBuilder()
           .setReadStream(
               ReadStreamName.of("[PROJECT]", "[LOCATION]", "[SESSION]", "[STREAM]").toString())
           .setOffset(-1019779949)
           .build();
   ServerStream<ReadRowsResponse> stream =
       baseBigQueryReadClient.readRowsCallable().call(request);
   for (ReadRowsResponse response : stream) {
     // Do something when a response is received.
   }
 }
Returns
Type Description
ServerStreamingCallable<ReadRowsRequest,ReadRowsResponse>

shutdown()

public void shutdown()

shutdownNow()

public void shutdownNow()

splitReadStream(SplitReadStreamRequest request)

public final SplitReadStreamResponse splitReadStream(SplitReadStreamRequest 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:


 // This snippet has been automatically generated and should be regarded as a code template only.
 // It will require modifications to work:
 // - It may require correct/in-range values for request initialization.
 // - It may require specifying regional endpoints when creating the service client as shown in
 // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 try (BaseBigQueryReadClient baseBigQueryReadClient = BaseBigQueryReadClient.create()) {
   SplitReadStreamRequest request =
       SplitReadStreamRequest.newBuilder()
           .setName(
               ReadStreamName.of("[PROJECT]", "[LOCATION]", "[SESSION]", "[STREAM]").toString())
           .setFraction(-1653751294)
           .build();
   SplitReadStreamResponse response = baseBigQueryReadClient.splitReadStream(request);
 }
Parameter
Name Description
request SplitReadStreamRequest

The request object containing all of the parameters for the API call.
Returns
Type Description
SplitReadStreamResponse

splitReadStreamCallable()

public final UnaryCallable<SplitReadStreamRequest,SplitReadStreamResponse> splitReadStreamCallable()

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:


 // This snippet has been automatically generated and should be regarded as a code template only.
 // It will require modifications to work:
 // - It may require correct/in-range values for request initialization.
 // - It may require specifying regional endpoints when creating the service client as shown in
 // https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
 try (BaseBigQueryReadClient baseBigQueryReadClient = BaseBigQueryReadClient.create()) {
   SplitReadStreamRequest request =
       SplitReadStreamRequest.newBuilder()
           .setName(
               ReadStreamName.of("[PROJECT]", "[LOCATION]", "[SESSION]", "[STREAM]").toString())
           .setFraction(-1653751294)
           .build();
   ApiFuture<SplitReadStreamResponse> future =
       baseBigQueryReadClient.splitReadStreamCallable().futureCall(request);
   // Do something.
   SplitReadStreamResponse response = future.get();
 }
Returns
Type Description
UnaryCallable<SplitReadStreamRequest,SplitReadStreamResponse>