Google BigQuery Storage V1 Client - Class BigQueryReadClient (1.3.2)

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
Name	Description
`project`	`string`

Returns
Type	Description
`string`	The formatted project resource.

readSessionName

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

Parameters
Name	Description
`project`	`string`
`location`	`string`
`session`	`string`

Returns
Type	Description
`string`	The formatted read_session resource.

readStreamName

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

Parameters
Name	Description
`project`	`string`
`location`	`string`
`session`	`string`
`stream`	`string`

Returns
Type	Description
`string`	The formatted read_stream resource.

tableName

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

Parameters
Name	Description
`project`	`string`
`dataset`	`string`
`table`	`string`

Returns
Type	Description
`string`	The 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
Name	Description
`formattedName`	`string` The formatted name string
`template`	`string` Optional name of template to match

Returns
Type	Description
`array`	An associative array from name component IDs to component values.

__construct

Constructor.

Parameters
Name	Description
`options`	`array` Optional. Options for configuring the service API wrapper.
`↳ 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 $apiEndpoint 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 6 hours after they are created and do not require manual clean-up by the caller.

Parameters
Name	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.
`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. 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.
`↳ preferredMinStreamCount`	`int` The minimum preferred stream count. This parameter can be used to inform the service that there is a desired lower bound on the number of streams. This is typically a target parallelism of the client (e.g. a Spark cluster with N-workers would set this to a low multiple of N to ensure good cluster utilization). The system will make a best effort to provide at least this number of streams, but in some cases might provide less.
`↳ retrySettings`	`RetrySettings\|array` Retry settings to use for this call. Can be a Google\ApiCore\RetrySettings object, or an associative array of retry settings parameters. See the documentation on Google\ApiCore\RetrySettings for example usage.

Returns
Type	Description
`Google\Cloud\BigQuery\Storage\V1\ReadSession`

Example

use Google\ApiCore\ApiException;
use Google\Cloud\BigQuery\Storage\V1\BigQueryReadClient;
use Google\Cloud\BigQuery\Storage\V1\ReadSession;

/**
 * @param string $formattedParent The request project that owns the session, in the form of
 *                                `projects/{project_id}`. Please see
 *                                {@see BigQueryReadClient::projectName()} for help formatting this field.
 */
function create_read_session_sample(string $formattedParent): void
{
    // Create a client.
    $bigQueryReadClient = new BigQueryReadClient();

    // Prepare any non-scalar elements to be passed along with the request.
    $readSession = new ReadSession();

    // Call the API and handle any network failures.
    try {
        /** @var ReadSession $response */
        $response = $bigQueryReadClient->createReadSession($formattedParent, $readSession);
        printf('Response data: %s' . PHP_EOL, $response->serializeToJsonString());
    } catch (ApiException $ex) {
        printf('Call failed with message: %s' . PHP_EOL, $ex->getMessage());
    }
}

/**
 * This sample 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,
 *    please see the apiEndpoint client configuration option for more details.
 */
function callSample(): void
{
    $formattedParent = BigQueryReadClient::projectName('[PROJECT]');

    create_read_session_sample($formattedParent);
}

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.

Parameters
Name	Description
`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
Type	Description
`Google\ApiCore\ServerStream`

Example

use Google\ApiCore\ApiException;
use Google\ApiCore\ServerStream;
use Google\Cloud\BigQuery\Storage\V1\BigQueryReadClient;
use Google\Cloud\BigQuery\Storage\V1\ReadRowsResponse;

/**
 * @param string $formattedReadStream Stream to read rows from. Please see
 *                                    {@see BigQueryReadClient::readStreamName()} for help formatting this field.
 */
function read_rows_sample(string $formattedReadStream): void
{
    // Create a client.
    $bigQueryReadClient = new BigQueryReadClient();

    // Call the API and handle any network failures.
    try {
        /** @var ServerStream $stream */
        $stream = $bigQueryReadClient->readRows($formattedReadStream);

        /** @var ReadRowsResponse $element */
        foreach ($stream->readAll() as $element) {
            printf('Element data: %s' . PHP_EOL, $element->serializeToJsonString());
        }
    } catch (ApiException $ex) {
        printf('Call failed with message: %s' . PHP_EOL, $ex->getMessage());
    }
}

/**
 * This sample 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,
 *    please see the apiEndpoint client configuration option for more details.
 */
function callSample(): void
{
    $formattedReadStream = BigQueryReadClient::readStreamName(
        '[PROJECT]',
        '[LOCATION]',
        '[SESSION]',
        '[STREAM]'
    );

    read_rows_sample($formattedReadStream);
}

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.

Parameters
Name	Description
`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\ApiCore\RetrySettings object, or an associative array of retry settings parameters. See the documentation on Google\ApiCore\RetrySettings for example usage.

Returns
Type	Description
`Google\Cloud\BigQuery\Storage\V1\SplitReadStreamResponse`

Example

use Google\ApiCore\ApiException;
use Google\Cloud\BigQuery\Storage\V1\BigQueryReadClient;
use Google\Cloud\BigQuery\Storage\V1\SplitReadStreamResponse;

/**
 * @param string $formattedName Name of the stream to split. Please see
 *                              {@see BigQueryReadClient::readStreamName()} for help formatting this field.
 */
function split_read_stream_sample(string $formattedName): void
{
    // Create a client.
    $bigQueryReadClient = new BigQueryReadClient();

    // Call the API and handle any network failures.
    try {
        /** @var SplitReadStreamResponse $response */
        $response = $bigQueryReadClient->splitReadStream($formattedName);
        printf('Response data: %s' . PHP_EOL, $response->serializeToJsonString());
    } catch (ApiException $ex) {
        printf('Call failed with message: %s' . PHP_EOL, $ex->getMessage());
    }
}

/**
 * This sample 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,
 *    please see the apiEndpoint client configuration option for more details.
 */
function callSample(): void
{
    $formattedName = BigQueryReadClient::readStreamName(
        '[PROJECT]',
        '[LOCATION]',
        '[SESSION]',
        '[STREAM]'
    );

    split_read_stream_sample($formattedName);
}

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.