Package google.cloud.bigquery.storage.v1

Index

BigQueryRead

BigQuery Read API.

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

CreateReadSession

rpc CreateReadSession(CreateReadSessionRequest) returns (ReadSession)

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.

ReadRows

rpc ReadRows(ReadRowsRequest) returns (ReadRowsResponse)

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.

SplitReadStream

rpc SplitReadStream(SplitReadStreamRequest) returns (SplitReadStreamResponse)

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.

ArrowRecordBatch

Arrow RecordBatch.

Fields
serialized_record_batch

bytes

IPC-serialized Arrow RecordBatch.

row_count

int64

The count of rows in serialized_record_batch.

ArrowSchema

Arrow schema as specified in https://arrow.apache.org/docs/python/api/datatypes.html and serialized to bytes using IPC: https://arrow.apache.org/docs/format/Columnar.html#serialization-and-interprocess-communication-ipc

See code samples on how this message can be deserialized.

Fields
serialized_schema

bytes

IPC serialized Arrow schema.

AvroRows

Avro rows.

Fields
serialized_binary_rows

bytes

Binary serialized rows in a block.

row_count

int64

The count of rows in the returning block.

AvroSchema

Avro schema.

Fields
schema

string

Json serialized schema, as described at https://avro.apache.org/docs/1.8.1/spec.html.

CreateReadSessionRequest

Request message for CreateReadSession.

Fields
parent

string

Required. The request project that owns the session, in the form of projects/{project_id}.

Authorization requires the following IAM permission on the specified resource parent:

  • bigquery.readsessions.create
read_session

ReadSession

Required. Session to be created.

Authorization requires the following IAM permission on the specified resource readSession:

  • bigquery.tables.getData
max_stream_count

int32

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.

DataFormat

Data format for input or output data.

Enums
DATA_FORMAT_UNSPECIFIED
AVRO Avro is a standard open source row based file format. See https://avro.apache.org/ for more details.
ARROW Arrow is a standard open source column-based message format. See https://arrow.apache.org/ for more details.

ReadRowsRequest

Request message for ReadRows.

Fields
read_stream

string

Required. Stream to read rows from.

Authorization requires the following IAM permission on the specified resource readStream:

  • bigquery.readsessions.getData
offset

int64

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.

ReadRowsResponse

Response from calling ReadRows may include row data, progress and throttling information.

Fields
row_count

int64

Number of serialized rows in the rows block.

stats

StreamStats

Statistics for the stream.

throttle_state

ThrottleState

Throttling state. If unset, the latest response still describes the current throttling status.

Union field rows. Row data is returned in format specified during session creation. rows can be only one of the following:
avro_rows

AvroRows

Serialized row data in AVRO format.

arrow_record_batch

ArrowRecordBatch

Serialized row data in Arrow RecordBatch format.

ReadSession

Information about the ReadSession.

Fields
name

string

Output only. Unique identifier for the session, in the form projects/{project_id}/locations/{location}/sessions/{session_id}.

expire_time

Timestamp

Output only. Time at which the session becomes invalid. After this time, subsequent requests to read this Session will return errors. The expire_time is automatically assigned and currently cannot be specified or updated.

data_format

DataFormat

Immutable. Data format of the output data.

table

string

Immutable. Table that this ReadSession is reading from, in the form projects/{project_id}/datasets/{dataset_id}/tables/{table_id}

Authorization requires one or more of the following IAM permissions on the specified resource table:

  • bigquery.tables.get
  • bigquery.tables.getData
table_modifiers

TableModifiers

Optional. Any modifiers which are applied when reading from the specified table.

read_options

TableReadOptions

Optional. Read options for this session (e.g. column selection, filters).

streams[]

ReadStream

Output only. A list of streams created with the session.

At least one stream is created with the session. In the future, larger request_stream_count values may result in this list being unpopulated, in that case, the user will need to use a List method to get the streams instead, which is not yet available.

Union field schema. The schema for the read. If read_options.selected_fields is set, the schema may be different from the table schema as it will only contain the selected fields. schema can be only one of the following:
avro_schema

AvroSchema

Output only. Avro schema.

arrow_schema

ArrowSchema

Output only. Arrow schema.

TableModifiers

Additional attributes when reading a table.

Fields
snapshot_time

Timestamp

The snapshot time of the table. If not set, interpreted as now.

TableReadOptions

Options dictating how we read a table.

Fields
selected_fields[]

string

Names of the fields in the table that should be read. If empty, all fields will be read. If the specified field is a nested field, all the sub-fields in the field will be selected. The output field order is unrelated to the order of fields in selected_fields.

row_restriction

string

SQL text filtering statement, similar to a WHERE clause in a query. Aggregates are not supported.

Examples: "int_field > 5" "date_field = CAST('2014-9-27' as DATE)" "nullable_field is not NULL" "st_equals(geo_field, st_geofromtext("POINT(2, 2)"))" "numeric_field BETWEEN 1.0 AND 5.0"

ReadStream

Information about a single stream that gets data out of the storage system. Most of the information about ReadStream instances is aggregated, making ReadStream lightweight.

Fields
name

string

Output only. Name of the stream, in the form projects/{project_id}/locations/{location}/sessions/{session_id}/streams/{stream_id}.

SplitReadStreamRequest

Request message for SplitReadStream.

Fields
name

string

Required. Name of the stream to split.

Authorization requires the following IAM permission on the specified resource name:

  • bigquery.readsessions.update
fraction

double

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.

SplitReadStreamResponse

Fields
primary_stream

ReadStream

Primary stream, which contains the beginning portion of |original_stream|. An empty value indicates that the original stream can no longer be split.

remainder_stream

ReadStream

Remainder stream, which contains the tail of |original_stream|. An empty value indicates that the original stream can no longer be split.

StreamStats

Estimated stream statistics for a given Stream.

Fields
progress

Progress

Represents the progress of the current stream.

Progress

Fields
at_response_start

double

The fraction of rows assigned to the stream that have been processed by the server so far, not including the rows in the current response message.

This value, along with at_response_end, can be used to interpolate the progress made as the rows in the message are being processed using the following formula: at_response_start + (at_response_end - at_response_start) * rows_processed_from_response / rows_in_response.

Note that if a filter is provided, the at_response_end value of the previous response may not necessarily be equal to the at_response_start value of the current response.

at_response_end

double

Similar to at_response_start, except that this value includes the rows in the current response.

ThrottleState

Information on if the current connection is being throttled.

Fields
throttle_percent

int32

How much this connection is being throttled. Zero means no throttling, 100 means fully throttled.