Source code for airflow.hooks.presto_hook

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from builtins import str

import prestodb
from prestodb.exceptions import DatabaseError
from prestodb.transaction import IsolationLevel

from airflow.hooks.dbapi_hook import DbApiHook





[docs]class PrestoHook(DbApiHook): """ Interact with Presto through PyHive! >>> ph = PrestoHook() >>> sql = "SELECT count(1) AS num FROM airflow.static_babynames" >>> ph.get_records(sql) [[340698]] """
[docs] conn_name_attr = 'presto_conn_id'
[docs] default_conn_name = 'presto_default'
[docs] def get_conn(self): """Returns a connection object""" db = self.get_connection(self.presto_conn_id) auth = prestodb.auth.BasicAuthentication(db.login, db.password) if db.password else None return prestodb.dbapi.connect( host=db.host, port=db.port, user=db.login, source=db.extra_dejson.get('source', 'airflow'), http_scheme=db.extra_dejson.get('protocol', 'http'), catalog=db.extra_dejson.get('catalog', 'hive'), schema=db.schema, auth=auth, isolation_level=self.get_isolation_level()
)
[docs] def get_isolation_level(self): """Returns an isolation level""" db = self.get_connection(self.presto_conn_id) isolation_level = db.extra_dejson.get('isolation_level', 'AUTOCOMMIT').upper() return getattr(IsolationLevel, isolation_level, IsolationLevel.AUTOCOMMIT)
@staticmethod
[docs] def _strip_sql(sql): return sql.strip().rstrip(';')
@staticmethod
[docs] def _get_pretty_exception_message(e): """ Parses some DatabaseError to provide a better error message """ if (hasattr(e, 'message') and 'errorName' in e.message and 'message' in e.message): return ('{name}: {message}'.format( name=e.message['errorName'], message=e.message['message'])) else: return str(e)
[docs] def get_records(self, hql, parameters=None): """ Get a set of records from Presto """ try: return super(PrestoHook, self).get_records( self._strip_sql(hql), parameters) except DatabaseError as e: raise PrestoException(self._get_pretty_exception_message(e))
[docs] def get_first(self, hql, parameters=None): """ Returns only the first row, regardless of how many rows the query returns. """ try: return super(PrestoHook, self).get_first( self._strip_sql(hql), parameters) except DatabaseError as e: raise PrestoException(self._get_pretty_exception_message(e))
[docs] def get_pandas_df(self, hql, parameters=None): """ Get a pandas dataframe from a sql query. """ import pandas cursor = self.get_cursor() try: cursor.execute(self._strip_sql(hql), parameters) data = cursor.fetchall() except DatabaseError as e: raise PrestoException(self._get_pretty_exception_message(e)) column_descriptions = cursor.description if data: df = pandas.DataFrame(data) df.columns = [c[0] for c in column_descriptions] else: df = pandas.DataFrame() return df
[docs] def run(self, hql, parameters=None): """ Execute the statement against Presto. Can be used to create views. """ return super(PrestoHook, self).run(self._strip_sql(hql), parameters)
[docs] def insert_rows(self, table, rows, target_fields=None, commit_every=0): """ A generic way to insert a set of tuples into a table. :param table: Name of the target table :type table: str :param rows: The rows to insert into the table :type rows: iterable of tuples :param target_fields: The names of the columns to fill in the table :type target_fields: iterable of strings :param commit_every: The maximum number of rows to insert in one transaction. Set to 0 to insert all rows in one transaction. :type commit_every: int """ if self.get_isolation_level() == IsolationLevel.AUTOCOMMIT: self.log.info( 'Transactions are not enable in presto connection. ' 'Please use the isolation_level property to enable it. ' 'Falling back to insert all rows in one transaction.' ) commit_every = 0 super(PrestoHook, self).insert_rows(table, rows, target_fields, commit_every)

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