TableReadOptions(mapping=None, *, ignore_unknown_fields=False, **kwargs)Options dictating how we read a table.
This message has oneof_ fields (mutually exclusive fields).
For each oneof, at most one member field can be set at the same time.
Setting any member of the oneof automatically clears all other
members.
.. _oneof: https://proto-plus-python.readthedocs.io/en/stable/fields.html#oneofs-mutually-exclusive-fields
Attributes |
|
|---|---|
| Name | Description |
selected_fields |
MutableSequence[str]
Optional. The names of the fields in the table to be returned. If no field names are specified, then all fields in the table are returned. Nested fields -- the child elements of a STRUCT field -- can be selected individually using their fully-qualified names, and will be returned as record fields containing only the selected nested fields. If a STRUCT field is specified in the selected fields list, all of the child elements will be returned. As an example, consider a table with the following schema: { "name": "struct_field", "type": "RECORD", "mode": "NULLABLE", "fields": [ { "name": "string_field1", "type": "STRING", . "mode": "NULLABLE" }, { "name": "string_field2", "type": "STRING", "mode": "NULLABLE" } ] } Specifying "struct_field" in the selected fields list will result in a read session schema with the following logical structure: struct_field { string_field1 string_field2 } Specifying "struct_field.string_field1" in the selected fields list will result in a read session schema with the following logical structure: struct_field { string_field1 } The order of the fields in the read session schema is derived from the table schema and does not correspond to the order in which the fields are specified in this list. |
row_restriction |
str
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" Restricted to a maximum length for 1 MB. |
arrow_serialization_options |
google.cloud.bigquery_storage_v1.types.ArrowSerializationOptions
Optional. Options specific to the Apache Arrow output format. This field is a member of oneof_ output_format_serialization_options.
|
avro_serialization_options |
google.cloud.bigquery_storage_v1.types.AvroSerializationOptions
Optional. Options specific to the Apache Avro output format This field is a member of oneof_ output_format_serialization_options.
|
sample_percentage |
float
Optional. Specifies a table sampling percentage. Specifically, the query planner will use TABLESAMPLE SYSTEM (sample_percentage PERCENT). The sampling percentage is applied at the data block granularity. It will randomly choose for each data block whether to read the rows in that data block. For more details, see https://cloud.google.com/bigquery/docs/table-sampling) This field is a member of oneof_ _sample_percentage.
|
response_compression_codec |
google.cloud.bigquery_storage_v1.types.ReadSession.TableReadOptions.ResponseCompressionCodec
Optional. Set response_compression_codec when creating a read session to enable application-level compression of ReadRows responses. This field is a member of oneof_ _response_compression_codec.
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Classes
ResponseCompressionCodec
ResponseCompressionCodec(value)Specifies which compression codec to attempt on the entire serialized response payload (either Arrow record batch or Avro rows). This is not to be confused with the Apache Arrow native compression codecs specified in ArrowSerializationOptions. For performance reasons, when creating a read session requesting Arrow responses, setting both native Arrow compression and application-level response compression will not be allowed - choose, at most, one kind of compression.
Enum values:
RESPONSE_COMPRESSION_CODEC_UNSPECIFIED (0):
Default is no compression.
RESPONSE_COMPRESSION_CODEC_LZ4 (2):
Use raw LZ4 compression.