Ticket #17266: 17266.diff

django/db/backends/postgresql_psycopg2/base.py

@@ -174 +174 @@
                 conn_params['port'] = settings_dict['PORT']
             self.connection = Database.connect(**conn_params)
             self.connection.set_client_encoding('UTF8')
-            # Set the time zone in autocommit mode (see #17062)
             tz = 'UTC' if settings.USE_TZ else settings_dict.get('TIME_ZONE')
-            if tz:
+            # Psycopg2 verions prior to 2.0.12 do not have get_parameter_status
+            # and there doesn't seem to be easy way to get psycog version - so
+            # guard agains older than 2.0.12 with an AttributeError
+            try:
+                conn_tz = self.connection.get_parameter_status('TimeZone')
+            except AttributeError:
+                conn_tz = None
+            # Set the time zone in autocommit mode (see #17062)
+            if tz and tz <> conn_tz:
                 self.connection.set_isolation_level(
                         psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT)
                 self.connection.cursor().execute("SET TIME ZONE %s", [tz])

docs/ref/databases.txt

@@ -33 +33 @@
 .. _known to be faulty: http://archives.postgresql.org/pgsql-bugs/2007-07/msg00046.php
 .. _Release 8.2.5: http://developer.postgresql.org/pgdocs/postgres/release-8-2-5.html
 
+Changing database's default settings
+------------------------------------
+
+It is a good idea to set the defaults for certain variables so that Django
+doesn't need to do that for every new connection. The variables in question
+are client_encoding, which should be set to 'UTF8', timezone, which should be
+set to settings TIME_ZONE if not using USE_TZ, else to 'UTC', and
+default_transaction_isolation which should be set to 'read committed'. You can
+set these variables directly in postgresql.conf, or more conveniently for the
+database user directly using `ALTER ROLE`_ db_user SET variable TO value.
+
+Django will work just fine if you don't do these changes, but each new
+connection will need to do additional queries to set the above mentioned
+variables.
+
+.. _ALTER ROLE: http://www.postgresql.org/docs/current/interactive/sql-alterrole.html
+
 Transaction handling
 ---------------------
 
@@ -48 +65 @@
 
 If your application is particularly read-heavy and doesn't make many
 database writes, the overhead of a constantly open transaction can
-sometimes be noticeable. For those situations, if you're using the
-``postgresql_psycopg2`` backend, you can configure Django to use
-*"autocommit"* behavior for the connection, meaning that each database
+sometimes be noticeable. For those situations, you can configure Django
+to use *"autocommit"* behavior for the connection, meaning that each database
 operation will normally be in its own transaction, rather than having
 the transaction extend over multiple operations. In this case, you can
 still manually start a transaction if you're doing something that