Class BaseBigQueryReadClient (2.12.3)

Version 2.12.3

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• 3.10.2
• 3.9.3
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public class BaseBigQueryReadClient implements BackgroundResource

Service Description: BigQuery Read API.

The Read API can be used to read data from BigQuery.

New code should use the v1 Read API going forward, if they don't use Write API at the same time.

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 (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().

The surface of this class includes several types of Java methods for each of the API's methods:

1. 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.
2. 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.
3. 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 BaseBigQueryReadSettings to create(). For example:

To customize credentials:

 BaseBigQueryReadSettings baseBigQueryReadSettings =
     BaseBigQueryReadSettings.newBuilder()
         .setCredentialsProvider(FixedCredentialsProvider.create(myCredentials))
         .build();
 BaseBigQueryReadClient baseBigQueryReadClient =
     BaseBigQueryReadClient.create(baseBigQueryReadSettings);
 

To customize the endpoint:

 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

Implements

BackgroundResource

Inherited Members

Object.clone()

Object.equals(Object)

Object.finalize()

Object.getClass()

Object.hashCode()

Object.notify()

Object.notifyAll()

Object.toString()

Object.wait()

Object.wait(long)

Object.wait(long,int)

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:

 try (BaseBigQueryReadClient baseBigQueryReadClient = BaseBigQueryReadClient.create()) {
   CreateReadSessionRequest request =
       CreateReadSessionRequest.newBuilder()
           .setParent(ProjectName.of("[PROJECT]").toString())
           .setReadSession(ReadSession.newBuilder().build())
           .setMaxStreamCount(940837515)
           .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:

 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. 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.

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:

 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. 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.

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:

 try (BaseBigQueryReadClient baseBigQueryReadClient = BaseBigQueryReadClient.create()) {
   CreateReadSessionRequest request =
       CreateReadSessionRequest.newBuilder()
           .setParent(ProjectName.of("[PROJECT]").toString())
           .setReadSession(ReadSession.newBuilder().build())
           .setMaxStreamCount(940837515)
           .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:

 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:

 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:

 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>