Airflow Summit 2021 is coming July 8-16. Register now!

Source code for airflow.providers.postgres.hooks.postgres

# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.

import os
from contextlib import closing
from copy import deepcopy
from typing import Iterable, Optional, Tuple, Union

import psycopg2
import psycopg2.extensions
import psycopg2.extras
from psycopg2.extensions import connection
from psycopg2.extras import DictCursor, NamedTupleCursor, RealDictCursor

from airflow.hooks.dbapi import DbApiHook
from airflow.models.connection import Connection

[docs]CursorType = Union[DictCursor, RealDictCursor, NamedTupleCursor]
[docs]class PostgresHook(DbApiHook): """ Interact with Postgres. You can specify ssl parameters in the extra field of your connection as ``{"sslmode": "require", "sslcert": "/path/to/cert.pem", etc}``. Also you can choose cursor as ``{"cursor": "dictcursor"}``. Refer to the psycopg2.extras for more details. Note: For Redshift, use keepalives_idle in the extra connection parameters and set it to less than 300 seconds. Note: For AWS IAM authentication, use iam in the extra connection parameters and set it to true. Leave the password field empty. This will use the "aws_default" connection to get the temporary token unless you override in extras. extras example: ``{"iam":true, "aws_conn_id":"my_aws_conn"}`` For Redshift, also use redshift in the extra connection parameters and set it to true. The cluster-identifier is extracted from the beginning of the host field, so is optional. It can however be overridden in the extra field. extras example: ``{"iam":true, "redshift":true, "cluster-identifier": "my_cluster_id"}`` :param postgres_conn_id: The :ref:`postgres conn id <howto/connection:postgres>` reference to a specific postgres database. :type postgres_conn_id: str """
[docs] conn_name_attr = 'postgres_conn_id'
[docs] default_conn_name = 'postgres_default'
[docs] conn_type = 'postgres'
[docs] hook_name = 'Postgres'
[docs] supports_autocommit = True
def __init__(self, *args, **kwargs) -> None: super().__init__(*args, **kwargs) self.connection: Optional[Connection] = kwargs.pop("connection", None) self.conn: connection = None def _get_cursor(self, raw_cursor: str) -> CursorType: _cursor = raw_cursor.lower() if _cursor == 'dictcursor': return psycopg2.extras.DictCursor if _cursor == 'realdictcursor': return psycopg2.extras.RealDictCursor if _cursor == 'namedtuplecursor': return psycopg2.extras.NamedTupleCursor raise ValueError(f'Invalid cursor passed {_cursor}')
[docs] def get_conn(self) -> connection: """Establishes a connection to a postgres database.""" conn_id = getattr(self, self.conn_name_attr) conn = deepcopy(self.connection or self.get_connection(conn_id)) # check for authentication via AWS IAM if conn.extra_dejson.get('iam', False): conn.login, conn.password, conn.port = self.get_iam_token(conn) conn_args = dict(, user=conn.login, password=conn.password, dbname=self.schema or conn.schema, port=conn.port, ) raw_cursor = conn.extra_dejson.get('cursor', False) if raw_cursor: conn_args['cursor_factory'] = self._get_cursor(raw_cursor) for arg_name, arg_val in conn.extra_dejson.items(): if arg_name not in [ 'iam', 'redshift', 'cursor', 'cluster-identifier', 'aws_conn_id', ]: conn_args[arg_name] = arg_val self.conn = psycopg2.connect(**conn_args) return self.conn
[docs] def copy_expert(self, sql: str, filename: str) -> None: """ Executes SQL using psycopg2 copy_expert method. Necessary to execute COPY command without access to a superuser. Note: if this method is called with a "COPY FROM" statement and the specified input file does not exist, it creates an empty file and no data is loaded, but the operation succeeds. So if users want to be aware when the input file does not exist, they have to check its existence by themselves. """ if not os.path.isfile(filename): with open(filename, 'w'): pass with open(filename, 'r+') as file: with closing(self.get_conn()) as conn: with closing(conn.cursor()) as cur: cur.copy_expert(sql, file) file.truncate(file.tell()) conn.commit()
[docs] def bulk_load(self, table: str, tmp_file: str) -> None: """Loads a tab-delimited file into a database table""" self.copy_expert(f"COPY {table} FROM STDIN", tmp_file)
[docs] def bulk_dump(self, table: str, tmp_file: str) -> None: """Dumps a database table into a tab-delimited file""" self.copy_expert(f"COPY {table} TO STDOUT", tmp_file)
@staticmethod def _serialize_cell(cell: object, conn: Optional[connection] = None) -> object: """ Postgresql will adapt all arguments to the execute() method internally, hence we return cell without any conversion. See for more information. :param cell: The cell to insert into the table :type cell: object :param conn: The database connection :type conn: connection object :return: The cell :rtype: object """ return cell
[docs] def get_iam_token(self, conn: Connection) -> Tuple[str, str, int]: """ Uses AWSHook to retrieve a temporary password to connect to Postgres or Redshift. Port is required. If none is provided, default is used for each service """ from import AwsBaseHook redshift = conn.extra_dejson.get('redshift', False) aws_conn_id = conn.extra_dejson.get('aws_conn_id', 'aws_default') aws_hook = AwsBaseHook(aws_conn_id, client_type='rds') login = conn.login if conn.port is None: port = 5439 if redshift else 5432 else: port = conn.port if redshift: # Pull the custer-identifier from the beginning of the Redshift URL # ex. returns my-cluster cluster_identifier = conn.extra_dejson.get('cluster-identifier','.')[0]) client = aws_hook.get_client_type('redshift') cluster_creds = client.get_cluster_credentials( DbUser=conn.login, DbName=self.schema or conn.schema, ClusterIdentifier=cluster_identifier, AutoCreate=False, ) token = cluster_creds['DbPassword'] login = cluster_creds['DbUser'] else: token = aws_hook.conn.generate_db_auth_token(, port, conn.login) return login, token, port
@staticmethod def _generate_insert_sql( table: str, values: Tuple[str, ...], target_fields: Iterable[str], replace: bool, **kwargs ) -> str: """ Static helper method that generate the INSERT SQL statement. The REPLACE variant is specific to MySQL syntax. :param table: Name of the target table :type table: str :param values: The row to insert into the table :type values: tuple of cell values :param target_fields: The names of the columns to fill in the table :type target_fields: iterable of strings :param replace: Whether to replace instead of insert :type replace: bool :param replace_index: the column or list of column names to act as index for the ON CONFLICT clause :type replace_index: str or list :return: The generated INSERT or REPLACE SQL statement :rtype: str """ placeholders = [ "%s", ] * len(values) replace_index = kwargs.get("replace_index") if target_fields: target_fields_fragment = ", ".join(target_fields) target_fields_fragment = f"({target_fields_fragment})" else: target_fields_fragment = '' sql = f"INSERT INTO {table} {target_fields_fragment} VALUES ({','.join(placeholders)})" if replace: if target_fields is None: raise ValueError("PostgreSQL ON CONFLICT upsert syntax requires column names") if replace_index is None: raise ValueError("PostgreSQL ON CONFLICT upsert syntax requires an unique index") if isinstance(replace_index, str): replace_index = [replace_index] replace_index_set = set(replace_index) replace_target = [ "{0} = excluded.{0}".format(col) for col in target_fields if col not in replace_index_set ] sql += " ON CONFLICT ({}) DO UPDATE SET {}".format( ", ".join(replace_index), ", ".join(replace_target), ) return sql

Was this entry helpful?