ReadClient

reader. ReadClient

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

This class provides the ability to make remote calls to the backing service through method calls that map to API methods.

For supplementary information about the Read API, see: https://cloud.google.com/bigquery/docs/read-api

Constructor

new ReadClient()

Methods

(async) createReadSession(request) → {Promise.<string>}

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 Description
request Object

The request object that will be sent.

Properties
Name Type Description
parent string

Parent table that all the streams should belong to, in the form of projects/{project}.
table string

Parent table that all the streams should belong to, in the form of projects/{project}/datasets/{dataset}/tables/{table}.
Returns:
Type Description
Promise.<string>

} - The promise which resolves to the streamId.

(async) createReadStream(request) → {Promise.<string>}

Creates a ReadStream to the given stream name and ReadSession.

Parameters:
Name Type Description
request Object

The request object that will be sent.

Properties
Name Type Description
streamName string

Required. The id/name of read stream to read from.
session string

Required. Reference to the ReadSession. See createReadSession.
Returns:
Type Description
Promise.<string>

} - The promise which resolves to the ReadStream.

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 when auth is complete.