:mod:`airflow.contrib.operators.cassandra_to_gcs`
=================================================

.. py:module:: airflow.contrib.operators.cassandra_to_gcs

.. autoapi-nested-parse::

   This module contains operator for copying
   data from Cassandra to Google cloud storage in JSON format.


Module Contents
---------------

.. py:class:: CassandraToGoogleCloudStorageOperator(cql, bucket, filename, schema_filename=None, approx_max_file_size_bytes=1900000000, gzip=False, cassandra_conn_id='cassandra_default', google_cloud_storage_conn_id='google_cloud_default', delegate_to=None, *args, **kwargs)

   Bases: :class:`airflow.models.BaseOperator`

   Copy data from Cassandra to Google cloud storage in JSON format

   Note: Arrays of arrays are not supported.

   :param cql: The CQL to execute on the Cassandra table.
   :type cql: str
   :param bucket: The bucket to upload to.
   :type bucket: str
   :param filename: The filename to use as the object name when uploading
       to Google cloud storage. A {} should be specified in the filename
       to allow the operator to inject file numbers in cases where the
       file is split due to size.
   :type filename: str
   :param schema_filename: If set, the filename to use as the object name
       when uploading a .json file containing the BigQuery schema fields
       for the table that was dumped from MySQL.
   :type schema_filename: str
   :param approx_max_file_size_bytes: This operator supports the ability
       to split large table dumps into multiple files (see notes in the
       filename param docs above). This param allows developers to specify the
       file size of the splits. Check https://cloud.google.com/storage/quotas
       to see the maximum allowed file size for a single object.
   :type approx_max_file_size_bytes: long
   :param cassandra_conn_id: Reference to a specific Cassandra hook.
   :type cassandra_conn_id: str
   :param gzip: Option to compress file for upload
   :type gzip: bool
   :param google_cloud_storage_conn_id: Reference to a specific Google
       cloud storage hook.
   :type google_cloud_storage_conn_id: str
   :param delegate_to: The account to impersonate, if any. For this to
       work, the service account making the request must have domain-wide
       delegation enabled.
   :type delegate_to: str

   .. attribute:: template_fields
      :annotation: = ['cql', 'bucket', 'filename', 'schema_filename']

      
   .. attribute:: template_ext
      :annotation: = ['.cql']

      
   .. attribute:: ui_color
      :annotation: = #a0e08c

      
   .. attribute:: CQL_TYPE_MAP
      

   .. method:: execute(self, context)


   .. method:: _query_cassandra(self)

      Queries cassandra and returns a cursor to the results.


   .. method:: _write_local_data_files(self, cursor)

      Takes a cursor, and writes results to a local file.

      :return: A dictionary where keys are filenames to be used as object
          names in GCS, and values are file handles to local files that
          contain the data for the GCS objects.


   .. method:: _write_local_schema_file(self, cursor)

      Takes a cursor, and writes the BigQuery schema for the results to a
      local file system.

      :return: A dictionary where key is a filename to be used as an object
          name in GCS, and values are file handles to local files that
          contains the BigQuery schema fields in .json format.


   .. method:: _upload_to_gcs(self, files_to_upload)


   .. classmethod:: generate_data_dict(cls, names, values)


   .. classmethod:: convert_value(cls, name, value)


   .. classmethod:: convert_array_types(cls, name, value)


   .. classmethod:: convert_user_type(cls, name, value)

      Converts a user type to RECORD that contains n fields, where n is the
      number of attributes. Each element in the user type class will be converted to its
      corresponding data type in BQ.


   .. classmethod:: convert_tuple_type(cls, name, value)

      Converts a tuple to RECORD that contains n fields, each will be converted
      to its corresponding data type in bq and will be named 'field_<index>', where
      index is determined by the order of the tuple elements defined in cassandra.


   .. classmethod:: convert_map_type(cls, name, value)

      Converts a map to a repeated RECORD that contains two fields: 'key' and 'value',
      each will be converted to its corresponding data type in BQ.


   .. classmethod:: generate_schema_dict(cls, name, type)


   .. classmethod:: get_bq_fields(cls, name, type)


   .. classmethod:: is_simple_type(cls, type)


   .. classmethod:: is_array_type(cls, type)


   .. classmethod:: is_record_type(cls, type)


   .. classmethod:: get_bq_type(cls, type)


   .. classmethod:: get_bq_mode(cls, type)