/usr/lib/python2.7/dist-packages/sqlalchemy/dialects/postgresql/psycopg2.py is in python-sqlalchemy 0.9.8+dfsg-0.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 | # postgresql/psycopg2.py
# Copyright (C) 2005-2014 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.
.. seealso::
:ref:`psycopg2_disable_native_unicode`
* ``isolation_level``: This option, available for all PostgreSQL dialects,
includes the ``AUTOCOMMIT`` isolation level when using the psycopg2
dialect.
.. seealso::
:ref:`psycopg2_isolation_level`
* ``client_encoding``: sets the client encoding in a libpq-agnostic way,
using psycopg2's ``set_client_encoding()`` method.
.. seealso::
:ref:`psycopg2_unicode`
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.
.. _psycopg2_unicode:
Unicode with Psycopg2
----------------------
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 ``utf8``, as a more useful default::
# postgresql.conf file
# 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
:meth:`psycopg2:connection.set_client_encoding` method
on all new connections based on the value passed to
:func:`.create_engine` using the ``client_encoding`` parameter::
# set_client_encoding() setting;
# works for *all* Postgresql versions
engine = create_engine("postgresql://user:pass@host/dbname",
client_encoding='utf8')
This overrides the encoding specified in the Postgresql client configuration.
When using the parameter in this way, the psycopg2 driver emits
``SET client_encoding TO 'utf8'`` on the connection explicitly, and works
in all Postgresql versions.
Note that the ``client_encoding`` setting as passed to :func:`.create_engine`
is **not the same** as the more recently added ``client_encoding`` parameter
now supported by libpq directly. This is enabled when ``client_encoding``
is passed directly to ``psycopg2.connect()``, and from SQLAlchemy is passed
using the :paramref:`.create_engine.connect_args` parameter::
# libpq direct parameter setting;
# only works for Postgresql **9.1 and above**
engine = create_engine("postgresql://user:pass@host/dbname",
connect_args={'client_encoding': 'utf8'})
# using the query string is equivalent
engine = create_engine("postgresql://user:pass@host/dbname?client_encoding=utf8")
The above parameter was only added to libpq as of version 9.1 of Postgresql,
so using the previous method is better for cross-version support.
.. _psycopg2_disable_native_unicode:
Disabling Native Unicode
^^^^^^^^^^^^^^^^^^^^^^^^
SQLAlchemy can also be instructed to skip the usage of the psycopg2
``UNICODE`` extension and to instead utilize its 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 most DBAPIs now support unicode fully.
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.
.. seealso::
:ref:`postgresql_isolation_level`
:ref:`pg8000_isolation_level`
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)
.. _psycopg2_hstore::
HSTORE type
------------
The ``psycopg2`` DBAPI includes an extension to natively handle marshalling of
the HSTORE type. The SQLAlchemy psycopg2 dialect will enable this extension
by default when it is detected that the target database has the HSTORE
type set up for use. In other words, when the dialect makes the first
connection, a sequence like the following is performed:
1. Request the available HSTORE oids using
``psycopg2.extras.HstoreAdapter.get_oids()``.
If this function returns a list of HSTORE identifiers, we then determine
that the ``HSTORE`` extension is present.
2. If the ``use_native_hstore`` flag is at its default of ``True``, and
we've detected that ``HSTORE`` oids are available, the
``psycopg2.extensions.register_hstore()`` extension is invoked for all
connections.
The ``register_hstore()`` extension has the effect of **all Python
dictionaries being accepted as parameters regardless of the type of target
column in SQL**. The dictionaries are converted by this extension into a
textual HSTORE expression. If this behavior is not desired, disable the
use of the hstore extension by setting ``use_native_hstore`` to ``False`` as
follows::
engine = create_engine("postgresql+psycopg2://scott:tiger@localhost/test",
use_native_hstore=False)
The ``HSTORE`` type is **still supported** when the
``psycopg2.extensions.register_hstore()`` extension is not used. It merely
means that the coercion between Python dictionaries and the HSTORE
string format, on both the parameter side and the result side, will take
place within SQLAlchemy's own marshalling logic, and not that of ``psycopg2``
which may be more performant.
"""
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
from .json import JSON
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,
self._effective_decimal_return_scale)
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 result_processor(self, dialect, coltype):
if util.py2k and self.convert_unicode is True:
# we can't easily use PG's extensions here because
# the OID is on the fly, and we need to give it a python
# function anyway - not really worth it.
self.convert_unicode = "force_nocheck"
return super(_PGEnum, self).result_processor(dialect, coltype)
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)
class _PGJSON(JSON):
def result_processor(self, dialect, coltype):
if dialect._has_native_json:
return None
else:
return super(_PGJSON, 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'
if util.py2k:
supports_unicode_statements = False
default_paramstyle = 'pyformat'
# set to true based on psycopg2 version
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
_has_native_json = False
colspecs = util.update_copy(
PGDialect.colspecs,
{
sqltypes.Numeric: _PGNumeric,
ENUM: _PGEnum, # needs force_unicode
sqltypes.Enum: _PGEnum, # needs force_unicode
HSTORE: _PGHStore,
JSON: _PGJSON
}
)
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
self._has_native_json = self.psycopg2_version >= (2, 5)
# http://initd.org/psycopg/docs/news.html#what-s-new-in-psycopg-2-0-9
self.supports_sane_multi_rowcount = self.psycopg2_version >= (2, 0, 9)
@classmethod
def dbapi(cls):
import psycopg2
return psycopg2
@util.memoized_property
def _isolation_lookup(self):
from psycopg2 import 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)
extensions.register_type(extensions.UNICODEARRAY, 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 self.dbapi and self._json_deserializer:
def on_connect(conn):
extras.register_default_json(
conn, loads=self._json_deserializer)
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):
# check the "closed" flag. this might not be
# present on old psycopg2 versions. Also,
# this flag doesn't actually help in a lot of disconnect
# situations, so don't rely on it.
if getattr(connection, 'closed', False):
return True
# checks based on strings. in the case that .closed
# didn't cut it, fall back onto these.
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.
'terminating connection',
'closed the connection',
'connection not open',
'could not receive data from server',
'could not send data to 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',
# these can occur in newer SSL
'connection has been closed unexpectedly',
'SSL SYSCALL error: Bad file descriptor',
'SSL SYSCALL error: EOF detected',
]:
idx = str_e.find(msg)
if idx >= 0 and '"' not in str_e[:idx]:
return True
return False
dialect = PGDialect_psycopg2
|