From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Tue, 15 Mar 2016 21:21:05 +0000 (-0400)
Subject: - backport doc improvements from 31f96c27a5fea302358ba580313a2f742c12b83d re:
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4bac8ad16f647a41c3b740c0b5b75b57b0175270;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

- backport doc improvements from 31f96c27a5fea302358ba580313a2f742c12b83d re:
isolation_level settings for postgresql, mysql

(cherry picked from commit 49eb39366a0ca54ce973147802864fd7c359adb3)
---

diff --git a/lib/sqlalchemy/dialects/mysql/base.py b/lib/sqlalchemy/dialects/mysql/base.py
index a6251e8d50..9807a86376 100644
--- a/lib/sqlalchemy/dialects/mysql/base.py
+++ b/lib/sqlalchemy/dialects/mysql/base.py
@@ -111,19 +111,35 @@ to be used.
 Transaction Isolation Level
 ---------------------------
 
-:func:`.create_engine` accepts an :paramref:`.create_engine.isolation_level`
-parameter which results in the command ``SET SESSION
-TRANSACTION ISOLATION LEVEL <level>`` being invoked for
-every new connection. Valid values for this parameter are
-``READ COMMITTED``, ``READ UNCOMMITTED``,
-``REPEATABLE READ``, and ``SERIALIZABLE``::
+All MySQL dialects support setting of transaction isolation level
+both via a dialect-specific parameter :paramref:`.create_engine.isolation_level`
+accepted by :func:`.create_engine`,
+as well as the :paramref:`.Connection.execution_options.isolation_level`
+argument as passed to :meth:`.Connection.execution_options`.
+This feature works by issuing the command
+``SET SESSION TRANSACTION ISOLATION LEVEL <level>`` for
+each new connection.
+
+To set isolation level using :func:`.create_engine`::
 
     engine = create_engine(
                     "mysql://scott:tiger@localhost/test",
                     isolation_level="READ UNCOMMITTED"
                 )
 
-.. versionadded:: 0.7.6
+To set using per-connection execution options::
+
+    connection = engine.connect()
+    connection = connection.execution_options(
+        isolation_level="READ COMMITTED"
+    )
+
+Valid values for ``isolation_level`` include:
+
+* ``READ COMMITTED``
+* ``READ UNCOMMITTED``
+* ``REPEATABLE READ``
+* ``SERIALIZABLE``
 
 AUTO_INCREMENT Behavior
 -----------------------
diff --git a/lib/sqlalchemy/dialects/postgresql/base.py b/lib/sqlalchemy/dialects/postgresql/base.py
index 0532e223ec..2e57294efe 100644
--- a/lib/sqlalchemy/dialects/postgresql/base.py
+++ b/lib/sqlalchemy/dialects/postgresql/base.py
@@ -50,11 +50,12 @@ Transaction Isolation Level
 All Postgresql dialects support setting of transaction isolation level
 both via a dialect-specific parameter :paramref:`.create_engine.isolation_level`
 accepted by :func:`.create_engine`,
-as well as the ``isolation_level`` argument as passed to
+as well as the :paramref:`.Connection.execution_options.isolation_level` argument as passed to
 :meth:`.Connection.execution_options`.  When using a non-psycopg2 dialect,
 this feature works by issuing the command
 ``SET SESSION CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL <level>`` for
-each new connection.
+each new connection.  For the special AUTOCOMMIT isolation level, DBAPI-specific
+techniques are used.
 
 To set isolation level using :func:`.create_engine`::
 
@@ -76,10 +77,7 @@ Valid values for ``isolation_level`` include:
 * ``READ UNCOMMITTED``
 * ``REPEATABLE READ``
 * ``SERIALIZABLE``
-
-The :mod:`~sqlalchemy.dialects.postgresql.psycopg2` and
-:mod:`~sqlalchemy.dialects.postgresql.pg8000` dialects also offer the
-special level ``AUTOCOMMIT``.
+* ``AUTOCOMMIT`` - on psycopg2 / pg8000 only
 
 .. seealso::