Source code for airflow.operators.redshift_to_s3_operator

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from airflow.hooks.postgres_hook import PostgresHook
from airflow.hooks.S3_hook import S3Hook
from airflow.models import BaseOperator
from airflow.utils.decorators import apply_defaults


[docs]class RedshiftToS3Transfer(BaseOperator): """ Executes an UNLOAD command to s3 as a CSV with headers :param schema: reference to a specific schema in redshift database :type schema: string :param table: reference to a specific table in redshift database :type table: string :param s3_bucket: reference to a specific S3 bucket :type s3_bucket: string :param s3_key: reference to a specific S3 key :type s3_key: string :param redshift_conn_id: reference to a specific redshift database :type redshift_conn_id: string :param aws_conn_id: reference to a specific S3 connection :type aws_conn_id: string :param unload_options: reference to a list of UNLOAD options :type unload_options: list """ template_fields = () template_ext = () ui_color = '#ededed' @apply_defaults def __init__( self, schema, table, s3_bucket, s3_key, redshift_conn_id='redshift_default', aws_conn_id='aws_default', unload_options=tuple(), autocommit=False, parameters=None, include_header=False, *args, **kwargs): super(RedshiftToS3Transfer, self).__init__(*args, **kwargs) self.schema = schema self.table = table self.s3_bucket = s3_bucket self.s3_key = s3_key self.redshift_conn_id = redshift_conn_id self.aws_conn_id = aws_conn_id self.unload_options = unload_options self.autocommit = autocommit self.parameters = parameters self.include_header = include_header if self.include_header and \ 'PARALLEL OFF' not in [uo.upper().strip() for uo in unload_options]: self.unload_options = list(unload_options) + ['PARALLEL OFF', ] def execute(self, context): self.hook = PostgresHook(postgres_conn_id=self.redshift_conn_id) self.s3 = S3Hook(aws_conn_id=self.aws_conn_id) credentials = self.s3.get_credentials() unload_options = '\n\t\t\t'.join(self.unload_options) if self.include_header: self.log.info("Retrieving headers from %s.%s...", self.schema, self.table) columns_query = """SELECT column_name FROM information_schema.columns WHERE table_schema = '{schema}' AND table_name = '{table}' ORDER BY ordinal_position """.format(schema=self.schema, table=self.table) cursor = self.hook.get_conn().cursor() cursor.execute(columns_query) rows = cursor.fetchall() columns = [row[0] for row in rows] column_names = ', '.join("{0}".format(c) for c in columns) column_headers = ', '.join("\\'{0}\\'".format(c) for c in columns) column_castings = ', '.join("CAST({0} AS text) AS {0}".format(c) for c in columns) select_query = """SELECT {column_names} FROM (SELECT 2 sort_order, {column_castings} FROM {schema}.{table} UNION ALL SELECT 1 sort_order, {column_headers}) ORDER BY sort_order"""\ .format(column_names=column_names, column_castings=column_castings, column_headers=column_headers, schema=self.schema, table=self.table) else: select_query = "SELECT * FROM {schema}.{table}"\ .format(schema=self.schema, table=self.table) unload_query = """ UNLOAD ('{select_query}') TO 's3://{s3_bucket}/{s3_key}/{table}_' with credentials 'aws_access_key_id={access_key};aws_secret_access_key={secret_key}' {unload_options}; """.format(select_query=select_query, table=self.table, s3_bucket=self.s3_bucket, s3_key=self.s3_key, access_key=credentials.access_key, secret_key=credentials.secret_key, unload_options=unload_options) self.log.info('Executing UNLOAD command...') self.hook.run(unload_query, self.autocommit) self.log.info("UNLOAD command complete...")