Commit 9b7d512d authored by Aymeric Augustin's avatar Aymeric Augustin
Browse files

[1.7.x] Fixed #24318 -- Set the transaction isolation level with psycopg >= 2.4.2. 

Backport of 76356d96 from master
parent c16f9c2d

django/db/backends/postgresql_psycopg2/base.py

+23 −5
Original line number Diff line number Diff line
@@ -93,10 +93,6 @@ class DatabaseWrapper(BaseDatabaseWrapper): 
    def __init__(self, *args, **kwargs):

        super(DatabaseWrapper, self).__init__(*args, **kwargs)



        opts = self.settings_dict["OPTIONS"]

        RC = psycopg2.extensions.ISOLATION_LEVEL_READ_COMMITTED

        self.isolation_level = opts.get('isolation_level', RC)



        self.features = DatabaseFeatures(self)

        self.ops = DatabaseOperations(self)

        self.client = DatabaseClient(self)
@@ -131,7 +127,29 @@ class DatabaseWrapper(BaseDatabaseWrapper): 
        return conn_params



    def get_new_connection(self, conn_params):

        return Database.connect(**conn_params)

        connection = Database.connect(**conn_params)



        # self.isolation_level must be set:

        # - after connecting to the database in order to obtain the database's

        #   default when no value is explicitly specified in options.

        # - before calling _set_autocommit() because if autocommit is on, that

        #   will set connection.isolation_level to ISOLATION_LEVEL_AUTOCOMMIT;

        #   and if autocommit is off, on psycopg2 < 2.4.2, _set_autocommit()

        #   needs self.isolation_level.

        options = self.settings_dict['OPTIONS']

        try:

            self.isolation_level = options['isolation_level']

        except KeyError:

            self.isolation_level = connection.isolation_level

        else:

            # Set the isolation level to the value from OPTIONS. This isn't

            # needed on psycopg2 < 2.4.2 because it happens as a side-effect

            # of _set_autocommit(False).

            if (self.isolation_level != connection.isolation_level and

                    self.psycopg2_version >= (2, 4, 2)):

                connection.set_session(isolation_level=self.isolation_level)



        return connection



    def init_connection_state(self):

        settings_dict = self.settings_dict

docs/releases/1.7.5.txt

+4 −0
Original line number Diff line number Diff line
@@ -19,3 +19,7 @@ Bugfixes 


* Fixed crash in ``contrib.sites`` migrations when a default database isn't

  used (:ticket:`24332`).



* Added the ability to set the isolation level on PostgreSQL with psycopg2 ≥

  2.4.2 (:ticket:`24318`). It was advertised as a new feature in Django 1.6

  but it didn't work in practice.

tests/backends/tests.py

+28 −0
Original line number Diff line number Diff line
@@ -233,6 +233,34 @@ class PostgreSQLTests(TestCase): 
        finally:

            new_connection.close()



    def test_connect_isolation_level(self):

        """

        Regression test for #18130 and #24318.

        """

        from psycopg2.extensions import (

            ISOLATION_LEVEL_READ_COMMITTED as read_committed,

            ISOLATION_LEVEL_SERIALIZABLE as serializable,

        )



        # Since this is a django.test.TestCase, a transaction is in progress

        # and the isolation level isn't reported as 0. This test assumes that

        # PostgreSQL is configured with the default isolation level.



        # Check the level on the psycopg2 connection, not the Django wrapper.

        self.assertEqual(connection.connection.isolation_level, read_committed)



        databases = copy.deepcopy(settings.DATABASES)

        databases[DEFAULT_DB_ALIAS]['OPTIONS']['isolation_level'] = serializable

        new_connections = ConnectionHandler(databases)

        new_connection = new_connections[DEFAULT_DB_ALIAS]

        try:

            # Start a transaction so the isolation level isn't reported as 0.

            new_connection.set_autocommit(False)

            # Check the level on the psycopg2 connection, not the Django wrapper.

            self.assertEqual(new_connection.connection.isolation_level, serializable)

        finally:

            new_connection.close()



    def _select(self, val):

        with connection.cursor() as cursor:

            cursor.execute("SELECT %s", (val,))