Update sqlalchemy

libs/sqlalchemy/dialects/postgresql/base.py

@@ -47,9 +47,18 @@ Transaction Isolation Level
 :func:`.create_engine` accepts an ``isolation_level`` parameter which results
 in the command ``SET SESSION CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL
 <level>`` being invoked for every new connection. Valid values for this
-parameter are ``READ_COMMITTED``, ``READ_UNCOMMITTED``, ``REPEATABLE_READ``,
-and ``SERIALIZABLE``.  Note that the psycopg2 dialect does *not* use this
-technique and uses psycopg2-specific APIs (see that dialect for details).
+parameter are ``READ COMMITTED``, ``READ UNCOMMITTED``, ``REPEATABLE READ``,
+and ``SERIALIZABLE``::
+
+    engine = create_engine(
+                    "postgresql+pg8000://scott:tiger@localhost/test", 
+                    isolation_level="READ UNCOMMITTED"
+                )
+
+When using the psycopg2 dialect, a psycopg2-specific method of setting
+transaction isolation level is used, but the API of ``isolation_level``
+remains the same - see :ref:`psycopg2_isolation`.
+
 
 Remote / Cross-Schema Table Introspection
 -----------------------------------------

libs/sqlalchemy/dialects/postgresql/psycopg2.py

@@ -38,6 +38,26 @@ psycopg2-specific keyword arguments which are accepted by
 * *use_native_unicode* - Enable the usage of Psycopg2 "native unicode" mode
   per connection. True by default.
 
+Unix Domain Connections
+------------------------
+
+psycopg2 supports connecting via Unix domain connections.   When the ``host``
+portion of the URL is omitted, SQLAlchemy passes ``None`` to psycopg2,
+which specifies Unix-domain communication rather than TCP/IP communication::
+
+    create_engine("postgresql+psycopg2://user:password@/dbname")
+
+By default, the socket file used is to connect to a Unix-domain socket
+in ``/tmp``, or whatever socket directory was specified when PostgreSQL 
+was built.  This value can be overridden by passing a pathname to psycopg2,
+using ``host`` as an additional keyword argument::
+
+    create_engine("postgresql+psycopg2://user:password@/dbname?host=/var/lib/postgresql")
+
+See also:
+
+`PQconnectdbParams <http://www.postgresql.org/docs/9.1/static/libpq-connect.html#LIBPQ-PQCONNECTDBPARAMS>`_
+
 Per-Statement/Connection Execution Options
 -------------------------------------------
 
@@ -97,6 +117,8 @@ Transactions
 
 The psycopg2 dialect fully supports SAVEPOINT and two-phase commit operations.
 
+.. _psycopg2_isolation:
+
 Transaction Isolation Level
 ---------------------------