296 lines
9.0 KiB
Python
296 lines
9.0 KiB
Python
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# postgresql/pg8000.py
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# Copyright (C) 2005-2018 the SQLAlchemy authors and contributors <see AUTHORS
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# file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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"""
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.. dialect:: postgresql+pg8000
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:name: pg8000
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:dbapi: pg8000
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:connectstring: \
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postgresql+pg8000://user:password@host:port/dbname[?key=value&key=value...]
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:url: https://pythonhosted.org/pg8000/
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.. _pg8000_unicode:
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Unicode
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-------
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pg8000 will encode / decode string values between it and the server using the
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PostgreSQL ``client_encoding`` parameter; by default this is the value in
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the ``postgresql.conf`` file, which often defaults to ``SQL_ASCII``.
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Typically, this can be changed to ``utf-8``, as a more useful default::
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#client_encoding = sql_ascii # actually, defaults to database
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# encoding
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client_encoding = utf8
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The ``client_encoding`` can be overridden for a session by executing the SQL:
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SET CLIENT_ENCODING TO 'utf8';
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SQLAlchemy will execute this SQL on all new connections based on the value
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passed to :func:`.create_engine` using the ``client_encoding`` parameter::
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engine = create_engine(
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"postgresql+pg8000://user:pass@host/dbname", client_encoding='utf8')
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.. _pg8000_isolation_level:
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pg8000 Transaction Isolation Level
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-------------------------------------
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The pg8000 dialect offers the same isolation level settings as that
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of the :ref:`psycopg2 <psycopg2_isolation_level>` dialect:
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* ``READ COMMITTED``
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* ``READ UNCOMMITTED``
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* ``REPEATABLE READ``
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* ``SERIALIZABLE``
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* ``AUTOCOMMIT``
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.. versionadded:: 0.9.5 support for AUTOCOMMIT isolation level when using
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pg8000.
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.. seealso::
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:ref:`postgresql_isolation_level`
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:ref:`psycopg2_isolation_level`
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"""
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from ... import util, exc
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import decimal
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from ... import processors
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from ... import types as sqltypes
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from .base import (
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PGDialect, PGCompiler, PGIdentifierPreparer, PGExecutionContext,
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_DECIMAL_TYPES, _FLOAT_TYPES, _INT_TYPES, UUID)
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import re
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from sqlalchemy.dialects.postgresql.json import JSON
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from ...sql.elements import quoted_name
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try:
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from uuid import UUID as _python_UUID
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except ImportError:
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_python_UUID = None
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class _PGNumeric(sqltypes.Numeric):
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def result_processor(self, dialect, coltype):
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if self.asdecimal:
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if coltype in _FLOAT_TYPES:
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return processors.to_decimal_processor_factory(
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decimal.Decimal, self._effective_decimal_return_scale)
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elif coltype in _DECIMAL_TYPES or coltype in _INT_TYPES:
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# pg8000 returns Decimal natively for 1700
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return None
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else:
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raise exc.InvalidRequestError(
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"Unknown PG numeric type: %d" % coltype)
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else:
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if coltype in _FLOAT_TYPES:
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# pg8000 returns float natively for 701
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return None
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elif coltype in _DECIMAL_TYPES or coltype in _INT_TYPES:
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return processors.to_float
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else:
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raise exc.InvalidRequestError(
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"Unknown PG numeric type: %d" % coltype)
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class _PGNumericNoBind(_PGNumeric):
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def bind_processor(self, dialect):
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return None
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class _PGJSON(JSON):
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def result_processor(self, dialect, coltype):
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if dialect._dbapi_version > (1, 10, 1):
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return None # Has native JSON
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else:
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return super(_PGJSON, self).result_processor(dialect, coltype)
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class _PGUUID(UUID):
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def bind_processor(self, dialect):
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if not self.as_uuid:
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def process(value):
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if value is not None:
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value = _python_UUID(value)
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return value
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return process
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def result_processor(self, dialect, coltype):
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if not self.as_uuid:
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def process(value):
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if value is not None:
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value = str(value)
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return value
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return process
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class PGExecutionContext_pg8000(PGExecutionContext):
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pass
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class PGCompiler_pg8000(PGCompiler):
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def visit_mod_binary(self, binary, operator, **kw):
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return self.process(binary.left, **kw) + " %% " + \
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self.process(binary.right, **kw)
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def post_process_text(self, text):
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if '%%' in text:
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util.warn("The SQLAlchemy postgresql dialect "
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"now automatically escapes '%' in text() "
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"expressions to '%%'.")
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return text.replace('%', '%%')
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class PGIdentifierPreparer_pg8000(PGIdentifierPreparer):
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def _escape_identifier(self, value):
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value = value.replace(self.escape_quote, self.escape_to_quote)
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return value.replace('%', '%%')
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class PGDialect_pg8000(PGDialect):
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driver = 'pg8000'
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supports_unicode_statements = True
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supports_unicode_binds = True
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default_paramstyle = 'format'
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supports_sane_multi_rowcount = True
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execution_ctx_cls = PGExecutionContext_pg8000
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statement_compiler = PGCompiler_pg8000
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preparer = PGIdentifierPreparer_pg8000
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description_encoding = 'use_encoding'
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colspecs = util.update_copy(
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PGDialect.colspecs,
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{
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sqltypes.Numeric: _PGNumericNoBind,
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sqltypes.Float: _PGNumeric,
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JSON: _PGJSON,
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sqltypes.JSON: _PGJSON,
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UUID: _PGUUID
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}
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)
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def __init__(self, client_encoding=None, **kwargs):
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PGDialect.__init__(self, **kwargs)
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self.client_encoding = client_encoding
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def initialize(self, connection):
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self.supports_sane_multi_rowcount = self._dbapi_version >= (1, 9, 14)
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super(PGDialect_pg8000, self).initialize(connection)
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@util.memoized_property
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def _dbapi_version(self):
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if self.dbapi and hasattr(self.dbapi, '__version__'):
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return tuple(
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[
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int(x) for x in re.findall(
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r'(\d+)(?:[-\.]?|$)', self.dbapi.__version__)])
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else:
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return (99, 99, 99)
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@classmethod
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def dbapi(cls):
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return __import__('pg8000')
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def create_connect_args(self, url):
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opts = url.translate_connect_args(username='user')
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if 'port' in opts:
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opts['port'] = int(opts['port'])
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opts.update(url.query)
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return ([], opts)
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def is_disconnect(self, e, connection, cursor):
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return "connection is closed" in str(e)
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def set_isolation_level(self, connection, level):
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level = level.replace('_', ' ')
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# adjust for ConnectionFairy possibly being present
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if hasattr(connection, 'connection'):
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connection = connection.connection
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if level == 'AUTOCOMMIT':
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connection.autocommit = True
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elif level in self._isolation_lookup:
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connection.autocommit = False
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cursor = connection.cursor()
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cursor.execute(
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"SET SESSION CHARACTERISTICS AS TRANSACTION "
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"ISOLATION LEVEL %s" % level)
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cursor.execute("COMMIT")
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cursor.close()
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else:
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raise exc.ArgumentError(
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"Invalid value '%s' for isolation_level. "
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"Valid isolation levels for %s are %s or AUTOCOMMIT" %
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(level, self.name, ", ".join(self._isolation_lookup))
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)
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def set_client_encoding(self, connection, client_encoding):
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# adjust for ConnectionFairy possibly being present
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if hasattr(connection, 'connection'):
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connection = connection.connection
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cursor = connection.cursor()
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cursor.execute("SET CLIENT_ENCODING TO '" + client_encoding + "'")
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cursor.execute("COMMIT")
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cursor.close()
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def do_begin_twophase(self, connection, xid):
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connection.connection.tpc_begin((0, xid, ''))
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def do_prepare_twophase(self, connection, xid):
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connection.connection.tpc_prepare()
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def do_rollback_twophase(
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self, connection, xid, is_prepared=True, recover=False):
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connection.connection.tpc_rollback((0, xid, ''))
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def do_commit_twophase(
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self, connection, xid, is_prepared=True, recover=False):
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connection.connection.tpc_commit((0, xid, ''))
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def do_recover_twophase(self, connection):
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return [row[1] for row in connection.connection.tpc_recover()]
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def on_connect(self):
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fns = []
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def on_connect(conn):
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conn.py_types[quoted_name] = conn.py_types[util.text_type]
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fns.append(on_connect)
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if self.client_encoding is not None:
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def on_connect(conn):
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self.set_client_encoding(conn, self.client_encoding)
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fns.append(on_connect)
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if self.isolation_level is not None:
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def on_connect(conn):
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self.set_isolation_level(conn, self.isolation_level)
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fns.append(on_connect)
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if len(fns) > 0:
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def on_connect(conn):
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for fn in fns:
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fn(conn)
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return on_connect
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else:
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return None
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dialect = PGDialect_pg8000
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