Google BigQuery Storage V1 Client - Class BigQueryReadClient (1.2.12)

Reference documentation and code samples for the Google BigQuery Storage V1 Client class BigQueryReadClient.

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:

$bigQueryReadClient = new BigQueryReadClient();
try {
    $formattedParent = $bigQueryReadClient->projectName('[PROJECT]');
    $readSession = new ReadSession();
    $response = $bigQueryReadClient->createReadSession($formattedParent, $readSession);
} finally {
    $bigQueryReadClient->close();
}

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 parseName method to extract the individual identifiers contained within formatted names that are returned by the API.

Methods

projectName

Formats a string containing the fully-qualified path to represent a project resource.

Parameter
NameDescription
project string
Returns
TypeDescription
stringThe formatted project resource.

readSessionName

Formats a string containing the fully-qualified path to represent a read_session resource.

Parameters
NameDescription
project string
location string
session string
Returns
TypeDescription
stringThe formatted read_session resource.

readStreamName

Formats a string containing the fully-qualified path to represent a read_stream resource.

Parameters
NameDescription
project string
location string
session string
stream string
Returns
TypeDescription
stringThe formatted read_stream resource.

tableName

Formats a string containing the fully-qualified path to represent a table resource.

Parameters
NameDescription
project string
dataset string
table string
Returns
TypeDescription
stringThe formatted table resource.

parseName

Parses a formatted name string and returns an associative array of the components in the name.

The following name formats are supported: Template: Pattern

  • project: projects/{project}
  • readSession: projects/{project}/locations/{location}/sessions/{session}
  • readStream: projects/{project}/locations/{location}/sessions/{session}/streams/{stream}
  • table: projects/{project}/datasets/{dataset}/tables/{table}

The optional $template argument can be supplied to specify a particular pattern, and must match one of the templates listed above. If no $template argument is provided, or if the $template argument does not match one of the templates listed, then parseName will check each of the supported templates, and return the first match.

Parameters
NameDescription
formattedName string

The formatted name string

template string

Optional name of template to match

Returns
TypeDescription
arrayAn associative array from name component IDs to component values.

__construct

Constructor.

Parameters
NameDescription
options array

Optional. Options for configuring the service API wrapper.

↳ serviceAddress string

Deprecated. This option will be removed in a future major release. Please utilize the $apiEndpoint option instead.

↳ apiEndpoint string

The address of the API remote host. May optionally include the port, formatted as "

↳ credentials string|array|FetchAuthTokenInterface|CredentialsWrapper

The credentials to be used by the client to authorize API calls. This option accepts either a path to a credentials file, or a decoded credentials file as a PHP array. Advanced usage: In addition, this option can also accept a pre-constructed Google\Auth\FetchAuthTokenInterface object or Google\ApiCore\CredentialsWrapper object. Note that when one of these objects are provided, any settings in $credentialsConfig will be ignored.

↳ credentialsConfig array

Options used to configure credentials, including auth token caching, for the client. For a full list of supporting configuration options, see Google\ApiCore\CredentialsWrapper::build() .

↳ disableRetries bool

Determines whether or not retries defined by the client configuration should be disabled. Defaults to false.

↳ clientConfig string|array

Client method configuration, including retry settings. This option can be either a path to a JSON file, or a PHP array containing the decoded JSON data. By default this settings points to the default client config file, which is provided in the resources folder.

↳ transport string|TransportInterface

The transport used for executing network requests. May be either the string rest or grpc. Defaults to grpc if gRPC support is detected on the system. Advanced usage: Additionally, it is possible to pass in an already instantiated Google\ApiCore\Transport\TransportInterface object. Note that when this object is provided, any settings in $transportConfig, and any $serviceAddress setting, will be ignored.

↳ transportConfig array

Configuration options that will be used to construct the transport. Options for each supported transport type should be passed in a key for that transport. For example: $transportConfig = [ 'grpc' => [...], 'rest' => [...], ]; See the Google\ApiCore\Transport\GrpcTransport::build() and Google\ApiCore\Transport\RestTransport::build() methods for the supported options.

↳ clientCertSource callable

A callable which returns the client cert as a string. This can be used to provide a certificate and private key to the transport layer for mTLS.

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

Sample code:

$bigQueryReadClient = new BigQueryReadClient();
try {
    $formattedParent = $bigQueryReadClient->projectName('[PROJECT]');
    $readSession = new ReadSession();
    $response = $bigQueryReadClient->createReadSession($formattedParent, $readSession);
} finally {
    $bigQueryReadClient->close();
}
Parameters
NameDescription
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.

optionalArgs array

Optional.

↳ 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.

↳ retrySettings RetrySettings|array

Retry settings to use for this call. Can be a Google\Cloud\BigQuery\Storage\V1\Gapic\Google\ApiCore\RetrySettings object, or an associative array of retry settings parameters. See the documentation on Google\Cloud\BigQuery\Storage\V1\Gapic\Google\ApiCore\RetrySettings for example usage.

Returns
TypeDescription
Google\Cloud\BigQuery\Storage\V1\ReadSession

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.

Sample code:

$bigQueryReadClient = new BigQueryReadClient();
try {
    $formattedReadStream = $bigQueryReadClient->readStreamName('[PROJECT]', '[LOCATION]', '[SESSION]', '[STREAM]');
    // Read all responses until the stream is complete
    $stream = $bigQueryReadClient->readRows($formattedReadStream);
    foreach ($stream->readAll() as $element) {
        // doSomethingWith($element);
    }
} finally {
    $bigQueryReadClient->close();
}
Parameters
NameDescription
readStream string

Required. Stream to read rows from.

optionalArgs array

Optional.

↳ offset int

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.

↳ timeoutMillis int

Timeout to use for this call.

Returns
TypeDescription
Google\ApiCore\ServerStream

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.

Sample code:

$bigQueryReadClient = new BigQueryReadClient();
try {
    $formattedName = $bigQueryReadClient->readStreamName('[PROJECT]', '[LOCATION]', '[SESSION]', '[STREAM]');
    $response = $bigQueryReadClient->splitReadStream($formattedName);
} finally {
    $bigQueryReadClient->close();
}
Parameters
NameDescription
name string

Required. Name of the stream to split.

optionalArgs array

Optional.

↳ fraction float

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.

↳ retrySettings RetrySettings|array

Retry settings to use for this call. Can be a Google\Cloud\BigQuery\Storage\V1\Gapic\Google\ApiCore\RetrySettings object, or an associative array of retry settings parameters. See the documentation on Google\Cloud\BigQuery\Storage\V1\Gapic\Google\ApiCore\RetrySettings for example usage.

Returns
TypeDescription
Google\Cloud\BigQuery\Storage\V1\SplitReadStreamResponse

Constants

SERVICE_NAME

Value: 'google.cloud.bigquery.storage.v1.BigQueryRead'

The name of the service.

SERVICE_ADDRESS

Value: 'bigquerystorage.googleapis.com'

The default address of the service.

DEFAULT_SERVICE_PORT

Value: 443

The default port of the service.

CODEGEN_NAME

Value: 'gapic'

The name of the code generator, to be included in the agent header.