BigQueryReadClient

BigQueryReadClient

BigQuery Read API.

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

Constructor

new BigQueryReadClient(optionsopt)

Construct an instance of BigQueryReadClient.

Parameters:
Name Type Attributes Description
options object <optional>

The configuration object. The options accepted by the constructor are described in detail in this document. The common options are:

Properties
Name Type Attributes Description
credentials object <optional>

Credentials object.

Properties
Name Type Attributes Description
client_email string <optional>
private_key string <optional>
email string <optional>

Account email address. Required when using a .pem or .p12 keyFilename.
keyFilename string <optional>

Full path to the a .json, .pem, or .p12 key downloaded from the Google Developers Console. If you provide a path to a JSON file, the projectId option below is not necessary. NOTE: .pem and .p12 require you to specify options.email as well.
port number <optional>

The port on which to connect to the remote host.
projectId string <optional>

The project ID from the Google Developer's Console, e.g. 'grape-spaceship-123'. We will also check the environment variable GCLOUD_PROJECT for your project ID. If your app is running in an environment which supports Application Default Credentials, your project ID will be detected automatically.
apiEndpoint string <optional>

The domain name of the API remote host.
clientConfig gax.ClientConfig <optional>

Client configuration override. Follows the structure of gapicConfig.
fallback boolean <optional>

Use HTTP fallback mode. In fallback mode, a special browser-compatible transport implementation is used instead of gRPC transport. In browser context (if the window object is defined) the fallback mode is enabled automatically; set options.fallback to false if you need to override this behavior.

Members

apiEndpoint

The DNS address for this API service - same as servicePath(), exists for compatibility reasons.

port

The port for this API service.

scopes

The scopes needed to make gRPC calls for every method defined in this service.

servicePath

The DNS address for this API service.

Methods

close() → {Promise}

Terminate the gRPC channel and close the client.

The client will no longer be usable and all future behavior is undefined.

Returns:
Type Description
Promise

A promise that resolves when the client is closed.

createReadSession(request, optionsopt) → {Promise}

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.

Parameters:
Name Type Attributes Description
request Object

The request object that will be sent.

Properties
Name Type Description
parent string

Required. The request project that owns the session, in the form of projects/{project_id}.
readSession google.cloud.bigquery.storage.v1.ReadSession

Required. Session to be created.
maxStreamCount number

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.
options object <optional>

Call options. See CallOptions for more details.
Returns:
Type Description
Promise
  • The promise which resolves to an array. The first element of the array is an object representing ReadSession. Please see the documentation for more details and examples.
Example
const [response] = await client.createReadSession(request);

getProjectId() → {Promise}

Return the project ID used by this class.

Returns:
Type Description
Promise

A promise that resolves to string containing the project ID.

initialize() → {Promise}

Initialize the client. Performs asynchronous operations (such as authentication) and prepares the client. This function will be called automatically when any class method is called for the first time, but if you need to initialize it before calling an actual method, feel free to call initialize() directly.

You can await on this method if you want to make sure the client is initialized.

Returns:
Type Description
Promise

A promise that resolves to an authenticated service stub.

matchDatasetFromTableName(tableName) → {string}

Parse the dataset from Table resource.

Parameters:
Name Type Description
tableName string

A fully-qualified path representing Table resource.
Returns:
Type Description
string

A string representing the dataset.

matchDatasetFromWriteStreamName(writeStreamName) → {string}

Parse the dataset from WriteStream resource.

Parameters:
Name Type Description
writeStreamName string

A fully-qualified path representing WriteStream resource.
Returns:
Type Description
string

A string representing the dataset.

matchLocationFromReadSessionName(readSessionName) → {string}

Parse the location from ReadSession resource.

Parameters:
Name Type Description
readSessionName string

A fully-qualified path representing ReadSession resource.
Returns:
Type Description
string

A string representing the location.

matchLocationFromReadStreamName(readStreamName) → {string}

Parse the location from ReadStream resource.

Parameters:
Name Type Description
readStreamName string

A fully-qualified path representing ReadStream resource.
Returns:
Type Description
string

A string representing the location.

matchProjectFromProjectName(projectName) → {string}

Parse the project from Project resource.

Parameters:
Name Type Description
projectName string

A fully-qualified path representing Project resource.
Returns:
Type Description
string

A string representing the project.

matchProjectFromReadSessionName(readSessionName) → {string}

Parse the project from ReadSession resource.

Parameters:
Name Type Description
readSessionName string

A fully-qualified path representing ReadSession resource.
Returns:
Type Description
string

A string representing the project.

matchProjectFromReadStreamName(readStreamName) → {string}

Parse the project from ReadStream resource.

Parameters:
Name Type Description
readStreamName string

A fully-qualified path representing ReadStream resource.
Returns:
Type Description
string

A string representing the project.

matchProjectFromTableName(tableName) → {string}

Parse the project from Table resource.

Parameters:
Name Type Description
tableName string

A fully-qualified path representing Table resource.
Returns:
Type Description
string

A string representing the project.

matchProjectFromWriteStreamName(writeStreamName) → {string}

Parse the project from WriteStream resource.

Parameters:
Name Type Description
writeStreamName string

A fully-qualified path representing WriteStream resource.
Returns:
Type Description
string

A string representing the project.

matchSessionFromReadSessionName(readSessionName) → {string}

Parse the session from ReadSession resource.

Parameters:
Name Type Description
readSessionName string

A fully-qualified path representing ReadSession resource.
Returns:
Type Description
string

A string representing the session.

matchSessionFromReadStreamName(readStreamName) → {string}

Parse the session from ReadStream resource.

Parameters:
Name Type Description
readStreamName string

A fully-qualified path representing ReadStream resource.
Returns:
Type Description
string

A string representing the session.

matchStreamFromReadStreamName(readStreamName) → {string}

Parse the stream from ReadStream resource.

Parameters:
Name Type Description
readStreamName string

A fully-qualified path representing ReadStream resource.
Returns:
Type Description
string

A string representing the stream.

matchStreamFromWriteStreamName(writeStreamName) → {string}

Parse the stream from WriteStream resource.

Parameters:
Name Type Description
writeStreamName string

A fully-qualified path representing WriteStream resource.
Returns:
Type Description
string

A string representing the stream.

matchTableFromTableName(tableName) → {string}

Parse the table from Table resource.

Parameters:
Name Type Description
tableName string

A fully-qualified path representing Table resource.
Returns:
Type Description
string

A string representing the table.

matchTableFromWriteStreamName(writeStreamName) → {string}

Parse the table from WriteStream resource.

Parameters:
Name Type Description
writeStreamName string

A fully-qualified path representing WriteStream resource.
Returns:
Type Description
string

A string representing the table.

projectPath(project) → {string}

Return a fully-qualified project resource name string.

Parameters:
Name Type Description
project string
Returns:
Type Description
string

Resource name string.

readRows(request, optionsopt) → {Stream}

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.

Parameters:
Name Type Attributes Description
request Object

The request object that will be sent.

Properties
Name Type Description
readStream string

Required. Stream to read rows from.
offset number

The offset requested must be less than the last row read from Read. Requesting a larger offset is undefined. If not specified, start reading from offset zero.
options object <optional>

Call options. See CallOptions for more details.
Returns:
Type Description
Stream

An object stream which emits ReadRowsResponse on 'data' event. Please see the documentation for more details and examples.
Example
const stream = client.readRows(request);
stream.on('data', (response) => { ... });
stream.on('end', () => { ... });

readSessionPath(project, location, session) → {string}

Return a fully-qualified readSession resource name string.

Parameters:
Name Type Description
project string
location string
session string
Returns:
Type Description
string

Resource name string.

readStreamPath(project, location, session, stream) → {string}

Return a fully-qualified readStream resource name string.

Parameters:
Name Type Description
project string
location string
session string
stream string
Returns:
Type Description
string

Resource name string.

splitReadStream(request, optionsopt) → {Promise}

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.

Parameters:
Name Type Attributes Description
request Object

The request object that will be sent.

Properties
Name Type Description
name string

Required. Name of the stream to split.
fraction number

A value in the range (0.0, 1.0) that specifies the fractional point at which the original stream should be split. The actual split point is evaluated on pre-filtered rows, so if a filter is provided, then there is no guarantee that the division of the rows between the new child streams will be proportional to this fractional value. Additionally, because the server-side unit for assigning data is collections of rows, this fraction will always map to a data storage boundary on the server side.
options object <optional>

Call options. See CallOptions for more details.
Returns:
Type Description
Promise
  • The promise which resolves to an array. The first element of the array is an object representing SplitReadStreamResponse. Please see the documentation for more details and examples.
Example
const [response] = await client.splitReadStream(request);

tablePath(project, dataset, table) → {string}

Return a fully-qualified table resource name string.

Parameters:
Name Type Description
project string
dataset string
table string
Returns:
Type Description
string

Resource name string.

writeStreamPath(project, dataset, table, stream) → {string}

Return a fully-qualified writeStream resource name string.

Parameters:
Name Type Description
project string
dataset string
table string
stream string
Returns:
Type Description
string

Resource name string.