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import sys
from typing import Dict, List, Optional, Union

import redshift_connector
from redshift_connector import Connection as RedshiftConnection
from sqlalchemy import create_engine
from sqlalchemy.engine.url import URL

from airflow.hooks.dbapi import DbApiHook

if sys.version_info >= (3, 8):
    from functools import cached_property
    from cached_property import cached_property

[docs]class RedshiftSQLHook(DbApiHook): """ Execute statements against Amazon Redshift, using redshift_connector This hook requires the redshift_conn_id connection. :param redshift_conn_id: reference to :ref:`Amazon Redshift connection id<howto/connection:redshift>` .. note:: get_sqlalchemy_engine() and get_uri() depend on sqlalchemy-amazon-redshift """
[docs] conn_name_attr = 'redshift_conn_id'
[docs] default_conn_name = 'redshift_default'
[docs] conn_type = 'redshift'
[docs] hook_name = 'Amazon Redshift'
[docs] supports_autocommit = True
[docs] def get_ui_field_behavior() -> Dict: """Returns custom field behavior""" return { "hidden_fields": [], "relabeling": {'login': 'User', 'schema': 'Database'},
} @cached_property
[docs] def conn(self): return self.get_connection(self.redshift_conn_id) # type: ignore[attr-defined]
def _get_conn_params(self) -> Dict[str, Union[str, int]]: """Helper method to retrieve connection args""" conn = self.conn conn_params: Dict[str, Union[str, int]] = {} if conn.login: conn_params['user'] = conn.login if conn.password: conn_params['password'] = conn.password if conn_params['host'] = if conn.port: conn_params['port'] = conn.port if conn.schema: conn_params['database'] = conn.schema return conn_params
[docs] def get_uri(self) -> str: """Overrides DbApiHook get_uri to use redshift_connector sqlalchemy dialect as driver name""" conn_params = self._get_conn_params() if 'user' in conn_params: conn_params['username'] = conn_params.pop('user') return str(URL(drivername='redshift+redshift_connector', **conn_params))
[docs] def get_sqlalchemy_engine(self, engine_kwargs=None): """Overrides DbApiHook get_sqlalchemy_engine to pass redshift_connector specific kwargs""" conn_kwargs = self.conn.extra_dejson if engine_kwargs is None: engine_kwargs = {} if "connect_args" in engine_kwargs: engine_kwargs["connect_args"] = {**conn_kwargs, **engine_kwargs["connect_args"]} else: engine_kwargs["connect_args"] = conn_kwargs return create_engine(self.get_uri(), **engine_kwargs)
[docs] def get_table_primary_key(self, table: str, schema: Optional[str] = "public") -> Optional[List[str]]: """ Helper method that returns the table primary key :param table: Name of the target table :param table: Name of the target schema, public by default :return: Primary key columns list :rtype: List[str] """ sql = """ select kcu.column_name from information_schema.table_constraints tco join information_schema.key_column_usage kcu on kcu.constraint_name = tco.constraint_name and kcu.constraint_schema = tco.constraint_schema and kcu.constraint_name = tco.constraint_name where tco.constraint_type = 'PRIMARY KEY' and kcu.table_schema = %s and kcu.table_name = %s """ pk_columns = [row[0] for row in self.get_records(sql, (schema, table))] return pk_columns or None
[docs] def get_conn(self) -> RedshiftConnection: """Returns a redshift_connector.Connection object""" conn_params = self._get_conn_params() conn_kwargs_dejson = self.conn.extra_dejson conn_kwargs: Dict = {**conn_params, **conn_kwargs_dejson} return redshift_connector.connect(**conn_kwargs)

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