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no idea what "auto-commit" means here. some reorg.

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This commit is contained in:
Mike Bayer
2011-04-15 12:55:31 -04:00
parent 2d34ded2d8
commit 5cd415d264
1 changed files with 39 additions and 38 deletions
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lib/sqlalchemy/dialects/postgresql/psycopg2.py
+39 -38
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@@ -9,16 +9,53 @@
Driver
------
The psycopg2 driver is supported, available at http://pypi.python.org/pypi/psycopg2/ .
The psycopg2 driver is available at http://pypi.python.org/pypi/psycopg2/ .
The dialect has several behaviors which are specifically tailored towards compatibility
with this module.
Note that psycopg1 is **not** supported.
Connecting
----------
URLs are of the form
``postgresql+psycopg2://user:password@host:port/dbname[?key=value&key=value...]``.
psycopg2-specific keyword arguments which are accepted by
:func:`.create_engine()` are:
* *server_side_cursors* - Enable the usage of "server side cursors" for SQL
statements which support this feature. What this essentially means from a
psycopg2 point of view is that the cursor is created using a name, e.g.
``connection.cursor('some name')``, which has the effect that result rows are
not immediately pre-fetched and buffered after statement execution, but are
instead left on the server and only retrieved as needed. SQLAlchemy's
:class:`~sqlalchemy.engine.base.ResultProxy` uses special row-buffering
behavior when this feature is enabled, such that groups of 100 rows at a
time are fetched over the wire to reduce conversational overhead.
Note that the ``stream_results=True`` execution option is a more targeted
way of enabling this mode on a per-execution basis.
* *use_native_unicode* - Enable the usage of Psycopg2 "native unicode" mode
per connection. True by default.
Per-Statement/Connection Execution Options
-------------------------------------------
The following DBAPI-specific options are respected when used with
:meth:`.Connection.execution_options`, :meth:`.Executable.execution_options`,
:meth:`.Query.execution_options`, in addition to those not specific to DBAPIs:
* isolation_level - Set the transaction isolation level for the lifespan of a
:class:`.Connection` (can only be set on a connection, not a statement or query).
This includes the options ``SERIALIZABLE``, ``READ COMMITTED``,
``READ UNCOMMITTED`` and ``REPEATABLE READ``.
* stream_results - Enable or disable usage of server side cursors.
If ``None`` or not set, the ``server_side_cursors`` option of the :class:`.Engine` is used.
Unicode
-------
By default, the Psycopg2 driver uses the ``psycopg2.extensions.UNICODE``
By default, the psycopg2 driver uses the ``psycopg2.extensions.UNICODE``
extension, such that the DBAPI receives and returns all strings as Python
Unicode objects directly - SQLAlchemy passes these values through without
change. Note that this setting requires that the PG client encoding be set to
@@ -34,27 +71,6 @@ slight performance penalty, as SQLAlchemy now must translate unicode strings
to/from an encoding such as utf-8, a task that is handled more efficiently
within the Psycopg2 driver natively.
Connecting
----------
URLs are of the form
``postgresql+psycopg2://user:password@host:port/dbname[?key=value&key=value...]``.
psycopg2-specific keyword arguments which are accepted by
:func:`.create_engine()` are:
* *server_side_cursors* - Enable the usage of "server side cursors" for SQL
statements which support this feature. What this essentially means from a
psycopg2 point of view is that the cursor is created using a name, e.g.
`connection.cursor('some name')`, which has the effect that result rows are
not immediately pre-fetched and buffered after statement execution, but are
instead left on the server and only retrieved as needed. SQLAlchemy's
:class:`~sqlalchemy.engine.base.ResultProxy` uses special row-buffering
behavior when this feature is enabled, such that groups of 100 rows at a
time are fetched over the wire to reduce conversational overhead.
* *use_native_unicode* - Enable the usage of Psycopg2 "native unicode" mode
per connection. True by default.
Transactions
------------
@@ -79,21 +95,6 @@ The psycopg2 dialect will log Postgresql NOTICE messages via the
logging.getLogger('sqlalchemy.dialects.postgresql').setLevel(logging.INFO)
Per-Statement/Connection Execution Options
-------------------------------------------
The following DBAPI-specific options are respected when used with
:meth:`.Connection.execution_options`, :meth:`.Executable.execution_options`,
:meth:`.Query.execution_options`, in addition to those not specific to DBAPIs:
* isolation_level - Set the transaction isolation level for the lifespan of a
:class:`.Connection` (can only be set on a connection, not a statement or query).
This includes the options ``SERIALIZABLE``, ``READ COMMITTED``,
``READ UNCOMMITTED`` and ``REPEATABLE READ``.
* stream_results - Enable or disable usage of server side cursors.
If ``None`` or not set, the ``server_side_cursors`` option of the :class:`.Engine` is used. If
auto-commit is enabled, the option is ignored.
"""
import random