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# Copyright 2015 Oliver Cope
#
# Licensed 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
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import warnings
from contextlib import contextmanager
from yoyo.backends.base import DatabaseBackend
class PostgresqlBackend(DatabaseBackend):
"""
Backend for PostgreSQL and PostgreSQL compatible databases.
This backend uses psycopg2. See
:class:`yoyo.backends.core.postgresql.PostgresqlPsycopgBackend`
if you need psycopg3.
"""
driver_module = "psycopg2"
schema = None
list_tables_sql = (
"SELECT table_name FROM information_schema.tables "
"WHERE table_schema = :schema"
)
@property
def TRANSACTION_STATUS_IDLE(self):
from psycopg2.extensions import TRANSACTION_STATUS_IDLE
return TRANSACTION_STATUS_IDLE
def connect(self, dburi):
kwargs = {"dbname": dburi.database, "autocommit": True}
# Default to autocommit mode: without this psycopg sends a BEGIN before
# every query, causing a warning when we then explicitly start a
# transaction. This warning becomes an error in CockroachDB. See
# https://todo.sr.ht/~olly/yoyo/71
kwargs["autocommit"] = True
kwargs.update(dburi.args)
if dburi.username is not None:
kwargs["user"] = dburi.username
if dburi.password is not None:
kwargs["password"] = dburi.password
if dburi.port is not None:
kwargs["port"] = dburi.port
if dburi.hostname is not None:
kwargs["host"] = dburi.hostname
self.schema = kwargs.pop("schema", None)
autocommit = bool(kwargs.pop("autocommit"))
connection = self.driver.connect(**kwargs)
connection.autocommit = autocommit
return connection
@contextmanager
def disable_transactions(self):
with super(PostgresqlBackend, self).disable_transactions():
saved = self.connection.autocommit
self.connection.autocommit = True
yield
self.connection.autocommit = saved
def init_connection(self, connection):
if self.schema:
cursor = connection.cursor()
cursor.execute("SET search_path TO {}".format(self.schema))
def list_tables(self):
current_schema = self.execute("SELECT current_schema").fetchone()[0]
return super(PostgresqlBackend, self).list_tables(schema=current_schema)
def commit(self):
# The connection is in autocommit mode and ignores calls to
# ``commit()`` and ``rollback()``, so we have to issue the SQL directly
self.execute("COMMIT")
super().commit()
def rollback(self):
self.execute("ROLLBACK")
super().rollback()
def begin(self):
if self.connection.info.transaction_status != self.TRANSACTION_STATUS_IDLE:
warnings.warn(
"Nested transaction requested; "
"this will raise an exception in some "
"PostgreSQL-compatible databases"
)
return super().begin()
class PostgresqlPsycopgBackend(PostgresqlBackend):
"""
Like PostgresqlBackend, but using the newer Psycopg 3.
"""
driver_module = "psycopg"
@property
def TRANSACTION_STATUS_IDLE(self):
from psycopg.pq import TransactionStatus
return TransactionStatus.IDLE
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