You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
476 lines
18 KiB
Python
476 lines
18 KiB
Python
9 years ago
|
# postgresql/psycopg2.py
|
||
|
# Copyright (C) 2005-2013 the SQLAlchemy authors and contributors <see AUTHORS file>
|
||
|
#
|
||
|
# This module is part of SQLAlchemy and is released under
|
||
|
# the MIT License: http://www.opensource.org/licenses/mit-license.php
|
||
|
|
||
|
"""
|
||
|
.. dialect:: postgresql+psycopg2
|
||
|
:name: psycopg2
|
||
|
:dbapi: psycopg2
|
||
|
:connectstring: postgresql+psycopg2://user:password@host:port/dbname[?key=value&key=value...]
|
||
|
:url: http://pypi.python.org/pypi/psycopg2/
|
||
|
|
||
|
psycopg2 Connect Arguments
|
||
|
-----------------------------------
|
||
|
|
||
|
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.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.
|
||
|
* ``isolation_level``: This option, available for all Posgtresql dialects,
|
||
|
includes the ``AUTOCOMMIT`` isolation level when using the psycopg2
|
||
|
dialect. See :ref:`psycopg2_isolation_level`.
|
||
|
|
||
|
|
||
|
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
|
||
|
-------------------------------------------
|
||
|
|
||
|
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). See :ref:`psycopg2_isolation_level`.
|
||
|
|
||
|
* stream_results - Enable or disable usage of psycopg2 server side cursors -
|
||
|
this feature makes use of "named" cursors in combination with special
|
||
|
result handling methods so that result rows are not fully buffered.
|
||
|
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``
|
||
|
extension, such that the DBAPI receives and returns all strings as Python
|
||
|
Unicode objects directly - SQLAlchemy passes these values through without
|
||
|
change. Psycopg2 here will encode/decode string values based on the
|
||
|
current "client encoding" setting; by default this is the value in
|
||
|
the ``postgresql.conf`` file, which often defaults to ``SQL_ASCII``.
|
||
|
Typically, this can be changed to ``utf-8``, as a more useful default::
|
||
|
|
||
|
#client_encoding = sql_ascii # actually, defaults to database
|
||
|
# encoding
|
||
|
client_encoding = utf8
|
||
|
|
||
|
A second way to affect the client encoding is to set it within Psycopg2
|
||
|
locally. SQLAlchemy will call psycopg2's ``set_client_encoding()``
|
||
|
method (see: http://initd.org/psycopg/docs/connection.html#connection.set_client_encoding)
|
||
|
on all new connections based on the value passed to
|
||
|
:func:`.create_engine` using the ``client_encoding`` parameter::
|
||
|
|
||
|
engine = create_engine("postgresql://user:pass@host/dbname", client_encoding='utf8')
|
||
|
|
||
|
This overrides the encoding specified in the Postgresql client configuration.
|
||
|
|
||
|
.. versionadded:: 0.7.3
|
||
|
The psycopg2-specific ``client_encoding`` parameter to
|
||
|
:func:`.create_engine`.
|
||
|
|
||
|
SQLAlchemy can also be instructed to skip the usage of the psycopg2
|
||
|
``UNICODE`` extension and to instead utilize it's own unicode encode/decode
|
||
|
services, which are normally reserved only for those DBAPIs that don't
|
||
|
fully support unicode directly. Passing ``use_native_unicode=False`` to
|
||
|
:func:`.create_engine` will disable usage of ``psycopg2.extensions.UNICODE``.
|
||
|
SQLAlchemy will instead encode data itself into Python bytestrings on the way
|
||
|
in and coerce from bytes on the way back,
|
||
|
using the value of the :func:`.create_engine` ``encoding`` parameter, which
|
||
|
defaults to ``utf-8``.
|
||
|
SQLAlchemy's own unicode encode/decode functionality is steadily becoming
|
||
|
obsolete as more DBAPIs support unicode fully along with the approach of
|
||
|
Python 3; in modern usage psycopg2 should be relied upon to handle unicode.
|
||
|
|
||
|
Transactions
|
||
|
------------
|
||
|
|
||
|
The psycopg2 dialect fully supports SAVEPOINT and two-phase commit operations.
|
||
|
|
||
|
.. _psycopg2_isolation_level:
|
||
|
|
||
|
Psycopg2 Transaction Isolation Level
|
||
|
-------------------------------------
|
||
|
|
||
|
As discussed in :ref:`postgresql_isolation_level`,
|
||
|
all Postgresql dialects support setting of transaction isolation level
|
||
|
both via the ``isolation_level`` parameter passed to :func:`.create_engine`,
|
||
|
as well as the ``isolation_level`` argument used by :meth:`.Connection.execution_options`.
|
||
|
When using the psycopg2 dialect, these options make use of
|
||
|
psycopg2's ``set_isolation_level()`` connection method, rather than
|
||
|
emitting a Postgresql directive; this is because psycopg2's API-level
|
||
|
setting is always emitted at the start of each transaction in any case.
|
||
|
|
||
|
The psycopg2 dialect supports these constants for isolation level:
|
||
|
|
||
|
* ``READ COMMITTED``
|
||
|
* ``READ UNCOMMITTED``
|
||
|
* ``REPEATABLE READ``
|
||
|
* ``SERIALIZABLE``
|
||
|
* ``AUTOCOMMIT``
|
||
|
|
||
|
.. versionadded:: 0.8.2 support for AUTOCOMMIT isolation level when using
|
||
|
psycopg2.
|
||
|
|
||
|
|
||
|
NOTICE logging
|
||
|
---------------
|
||
|
|
||
|
The psycopg2 dialect will log Postgresql NOTICE messages via the
|
||
|
``sqlalchemy.dialects.postgresql`` logger::
|
||
|
|
||
|
import logging
|
||
|
logging.getLogger('sqlalchemy.dialects.postgresql').setLevel(logging.INFO)
|
||
|
|
||
|
HSTORE type
|
||
|
------------
|
||
|
|
||
|
The psycopg2 dialect will make use of the
|
||
|
``psycopg2.extensions.register_hstore()`` extension when using the HSTORE
|
||
|
type. This replaces SQLAlchemy's pure-Python HSTORE coercion which takes
|
||
|
effect for other DBAPIs.
|
||
|
|
||
|
"""
|
||
|
from __future__ import absolute_import
|
||
|
import re
|
||
|
import logging
|
||
|
|
||
|
from ... import util, exc
|
||
|
import decimal
|
||
|
from ... import processors
|
||
|
from ...engine import result as _result
|
||
|
from ...sql import expression
|
||
|
from ... import types as sqltypes
|
||
|
from .base import PGDialect, PGCompiler, \
|
||
|
PGIdentifierPreparer, PGExecutionContext, \
|
||
|
ENUM, ARRAY, _DECIMAL_TYPES, _FLOAT_TYPES,\
|
||
|
_INT_TYPES
|
||
|
from .hstore import HSTORE
|
||
|
|
||
|
|
||
|
logger = logging.getLogger('sqlalchemy.dialects.postgresql')
|
||
|
|
||
|
|
||
|
class _PGNumeric(sqltypes.Numeric):
|
||
|
def bind_processor(self, dialect):
|
||
|
return None
|
||
|
|
||
|
def result_processor(self, dialect, coltype):
|
||
|
if self.asdecimal:
|
||
|
if coltype in _FLOAT_TYPES:
|
||
|
return processors.to_decimal_processor_factory(decimal.Decimal)
|
||
|
elif coltype in _DECIMAL_TYPES or coltype in _INT_TYPES:
|
||
|
# pg8000 returns Decimal natively for 1700
|
||
|
return None
|
||
|
else:
|
||
|
raise exc.InvalidRequestError(
|
||
|
"Unknown PG numeric type: %d" % coltype)
|
||
|
else:
|
||
|
if coltype in _FLOAT_TYPES:
|
||
|
# pg8000 returns float natively for 701
|
||
|
return None
|
||
|
elif coltype in _DECIMAL_TYPES or coltype in _INT_TYPES:
|
||
|
return processors.to_float
|
||
|
else:
|
||
|
raise exc.InvalidRequestError(
|
||
|
"Unknown PG numeric type: %d" % coltype)
|
||
|
|
||
|
|
||
|
class _PGEnum(ENUM):
|
||
|
def __init__(self, *arg, **kw):
|
||
|
super(_PGEnum, self).__init__(*arg, **kw)
|
||
|
# Py2K
|
||
|
if self.convert_unicode:
|
||
|
self.convert_unicode = "force"
|
||
|
# end Py2K
|
||
|
|
||
|
|
||
|
class _PGArray(ARRAY):
|
||
|
def __init__(self, *arg, **kw):
|
||
|
super(_PGArray, self).__init__(*arg, **kw)
|
||
|
# Py2K
|
||
|
# FIXME: this check won't work for setups that
|
||
|
# have convert_unicode only on their create_engine().
|
||
|
if isinstance(self.item_type, sqltypes.String) and \
|
||
|
self.item_type.convert_unicode:
|
||
|
self.item_type.convert_unicode = "force"
|
||
|
# end Py2K
|
||
|
|
||
|
|
||
|
class _PGHStore(HSTORE):
|
||
|
def bind_processor(self, dialect):
|
||
|
if dialect._has_native_hstore:
|
||
|
return None
|
||
|
else:
|
||
|
return super(_PGHStore, self).bind_processor(dialect)
|
||
|
|
||
|
def result_processor(self, dialect, coltype):
|
||
|
if dialect._has_native_hstore:
|
||
|
return None
|
||
|
else:
|
||
|
return super(_PGHStore, self).result_processor(dialect, coltype)
|
||
|
|
||
|
# When we're handed literal SQL, ensure it's a SELECT-query. Since
|
||
|
# 8.3, combining cursors and "FOR UPDATE" has been fine.
|
||
|
SERVER_SIDE_CURSOR_RE = re.compile(
|
||
|
r'\s*SELECT',
|
||
|
re.I | re.UNICODE)
|
||
|
|
||
|
_server_side_id = util.counter()
|
||
|
|
||
|
|
||
|
class PGExecutionContext_psycopg2(PGExecutionContext):
|
||
|
def create_cursor(self):
|
||
|
# TODO: coverage for server side cursors + select.for_update()
|
||
|
|
||
|
if self.dialect.server_side_cursors:
|
||
|
is_server_side = \
|
||
|
self.execution_options.get('stream_results', True) and (
|
||
|
(self.compiled and isinstance(self.compiled.statement, expression.Selectable) \
|
||
|
or \
|
||
|
(
|
||
|
(not self.compiled or
|
||
|
isinstance(self.compiled.statement, expression.TextClause))
|
||
|
and self.statement and SERVER_SIDE_CURSOR_RE.match(self.statement))
|
||
|
)
|
||
|
)
|
||
|
else:
|
||
|
is_server_side = \
|
||
|
self.execution_options.get('stream_results', False)
|
||
|
|
||
|
self.__is_server_side = is_server_side
|
||
|
if is_server_side:
|
||
|
# use server-side cursors:
|
||
|
# http://lists.initd.org/pipermail/psycopg/2007-January/005251.html
|
||
|
ident = "c_%s_%s" % (hex(id(self))[2:], hex(_server_side_id())[2:])
|
||
|
return self._dbapi_connection.cursor(ident)
|
||
|
else:
|
||
|
return self._dbapi_connection.cursor()
|
||
|
|
||
|
def get_result_proxy(self):
|
||
|
# TODO: ouch
|
||
|
if logger.isEnabledFor(logging.INFO):
|
||
|
self._log_notices(self.cursor)
|
||
|
|
||
|
if self.__is_server_side:
|
||
|
return _result.BufferedRowResultProxy(self)
|
||
|
else:
|
||
|
return _result.ResultProxy(self)
|
||
|
|
||
|
def _log_notices(self, cursor):
|
||
|
for notice in cursor.connection.notices:
|
||
|
# NOTICE messages have a
|
||
|
# newline character at the end
|
||
|
logger.info(notice.rstrip())
|
||
|
|
||
|
cursor.connection.notices[:] = []
|
||
|
|
||
|
|
||
|
class PGCompiler_psycopg2(PGCompiler):
|
||
|
def visit_mod_binary(self, binary, operator, **kw):
|
||
|
return self.process(binary.left, **kw) + " %% " + \
|
||
|
self.process(binary.right, **kw)
|
||
|
|
||
|
def post_process_text(self, text):
|
||
|
return text.replace('%', '%%')
|
||
|
|
||
|
|
||
|
class PGIdentifierPreparer_psycopg2(PGIdentifierPreparer):
|
||
|
def _escape_identifier(self, value):
|
||
|
value = value.replace(self.escape_quote, self.escape_to_quote)
|
||
|
return value.replace('%', '%%')
|
||
|
|
||
|
|
||
|
class PGDialect_psycopg2(PGDialect):
|
||
|
driver = 'psycopg2'
|
||
|
# Py2K
|
||
|
supports_unicode_statements = False
|
||
|
# end Py2K
|
||
|
default_paramstyle = 'pyformat'
|
||
|
supports_sane_multi_rowcount = False
|
||
|
execution_ctx_cls = PGExecutionContext_psycopg2
|
||
|
statement_compiler = PGCompiler_psycopg2
|
||
|
preparer = PGIdentifierPreparer_psycopg2
|
||
|
psycopg2_version = (0, 0)
|
||
|
|
||
|
_has_native_hstore = False
|
||
|
|
||
|
colspecs = util.update_copy(
|
||
|
PGDialect.colspecs,
|
||
|
{
|
||
|
sqltypes.Numeric: _PGNumeric,
|
||
|
ENUM: _PGEnum, # needs force_unicode
|
||
|
sqltypes.Enum: _PGEnum, # needs force_unicode
|
||
|
ARRAY: _PGArray, # needs force_unicode
|
||
|
HSTORE: _PGHStore,
|
||
|
}
|
||
|
)
|
||
|
|
||
|
def __init__(self, server_side_cursors=False, use_native_unicode=True,
|
||
|
client_encoding=None,
|
||
|
use_native_hstore=True,
|
||
|
**kwargs):
|
||
|
PGDialect.__init__(self, **kwargs)
|
||
|
self.server_side_cursors = server_side_cursors
|
||
|
self.use_native_unicode = use_native_unicode
|
||
|
self.use_native_hstore = use_native_hstore
|
||
|
self.supports_unicode_binds = use_native_unicode
|
||
|
self.client_encoding = client_encoding
|
||
|
if self.dbapi and hasattr(self.dbapi, '__version__'):
|
||
|
m = re.match(r'(\d+)\.(\d+)(?:\.(\d+))?',
|
||
|
self.dbapi.__version__)
|
||
|
if m:
|
||
|
self.psycopg2_version = tuple(
|
||
|
int(x)
|
||
|
for x in m.group(1, 2, 3)
|
||
|
if x is not None)
|
||
|
|
||
|
def initialize(self, connection):
|
||
|
super(PGDialect_psycopg2, self).initialize(connection)
|
||
|
self._has_native_hstore = self.use_native_hstore and \
|
||
|
self._hstore_oids(connection.connection) \
|
||
|
is not None
|
||
|
|
||
|
@classmethod
|
||
|
def dbapi(cls):
|
||
|
import psycopg2
|
||
|
return psycopg2
|
||
|
|
||
|
@util.memoized_property
|
||
|
def _isolation_lookup(self):
|
||
|
extensions = __import__('psycopg2.extensions').extensions
|
||
|
return {
|
||
|
'AUTOCOMMIT': extensions.ISOLATION_LEVEL_AUTOCOMMIT,
|
||
|
'READ COMMITTED': extensions.ISOLATION_LEVEL_READ_COMMITTED,
|
||
|
'READ UNCOMMITTED': extensions.ISOLATION_LEVEL_READ_UNCOMMITTED,
|
||
|
'REPEATABLE READ': extensions.ISOLATION_LEVEL_REPEATABLE_READ,
|
||
|
'SERIALIZABLE': extensions.ISOLATION_LEVEL_SERIALIZABLE
|
||
|
}
|
||
|
|
||
|
def set_isolation_level(self, connection, level):
|
||
|
try:
|
||
|
level = self._isolation_lookup[level.replace('_', ' ')]
|
||
|
except KeyError:
|
||
|
raise exc.ArgumentError(
|
||
|
"Invalid value '%s' for isolation_level. "
|
||
|
"Valid isolation levels for %s are %s" %
|
||
|
(level, self.name, ", ".join(self._isolation_lookup))
|
||
|
)
|
||
|
|
||
|
connection.set_isolation_level(level)
|
||
|
|
||
|
def on_connect(self):
|
||
|
from psycopg2 import extras, extensions
|
||
|
|
||
|
fns = []
|
||
|
if self.client_encoding is not None:
|
||
|
def on_connect(conn):
|
||
|
conn.set_client_encoding(self.client_encoding)
|
||
|
fns.append(on_connect)
|
||
|
|
||
|
if self.isolation_level is not None:
|
||
|
def on_connect(conn):
|
||
|
self.set_isolation_level(conn, self.isolation_level)
|
||
|
fns.append(on_connect)
|
||
|
|
||
|
if self.dbapi and self.use_native_unicode:
|
||
|
def on_connect(conn):
|
||
|
extensions.register_type(extensions.UNICODE, conn)
|
||
|
fns.append(on_connect)
|
||
|
|
||
|
if self.dbapi and self.use_native_hstore:
|
||
|
def on_connect(conn):
|
||
|
hstore_oids = self._hstore_oids(conn)
|
||
|
if hstore_oids is not None:
|
||
|
oid, array_oid = hstore_oids
|
||
|
if util.py2k:
|
||
|
extras.register_hstore(conn, oid=oid,
|
||
|
array_oid=array_oid,
|
||
|
unicode=True)
|
||
|
else:
|
||
|
extras.register_hstore(conn, oid=oid,
|
||
|
array_oid=array_oid)
|
||
|
fns.append(on_connect)
|
||
|
|
||
|
if fns:
|
||
|
def on_connect(conn):
|
||
|
for fn in fns:
|
||
|
fn(conn)
|
||
|
return on_connect
|
||
|
else:
|
||
|
return None
|
||
|
|
||
|
@util.memoized_instancemethod
|
||
|
def _hstore_oids(self, conn):
|
||
|
if self.psycopg2_version >= (2, 4):
|
||
|
from psycopg2 import extras
|
||
|
oids = extras.HstoreAdapter.get_oids(conn)
|
||
|
if oids is not None and oids[0]:
|
||
|
return oids[0:2]
|
||
|
return None
|
||
|
|
||
|
def create_connect_args(self, url):
|
||
|
opts = url.translate_connect_args(username='user')
|
||
|
if 'port' in opts:
|
||
|
opts['port'] = int(opts['port'])
|
||
|
opts.update(url.query)
|
||
|
return ([], opts)
|
||
|
|
||
|
def is_disconnect(self, e, connection, cursor):
|
||
|
if isinstance(e, self.dbapi.Error):
|
||
|
str_e = str(e).partition("\n")[0]
|
||
|
for msg in [
|
||
|
# these error messages from libpq: interfaces/libpq/fe-misc.c
|
||
|
# and interfaces/libpq/fe-secure.c.
|
||
|
# TODO: these are sent through gettext in libpq and we can't
|
||
|
# check within other locales - consider using connection.closed
|
||
|
'terminating connection',
|
||
|
'closed the connection',
|
||
|
'connection not open',
|
||
|
'could not receive data from server',
|
||
|
# psycopg2 client errors, psycopg2/conenction.h, psycopg2/cursor.h
|
||
|
'connection already closed',
|
||
|
'cursor already closed',
|
||
|
# not sure where this path is originally from, it may
|
||
|
# be obsolete. It really says "losed", not "closed".
|
||
|
'losed the connection unexpectedly'
|
||
|
]:
|
||
|
idx = str_e.find(msg)
|
||
|
if idx >= 0 and '"' not in str_e[:idx]:
|
||
|
return True
|
||
|
return False
|
||
|
|
||
|
dialect = PGDialect_psycopg2
|