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편집 파일: psycopg2.py

# postgresql/psycopg2.py # Copyright (C) 2005-2019 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 r""" .. 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 :paramref:`.Connection.execution_options.stream_results` 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` * ``use_batch_mode``: This flag allows ``psycopg2.extras.execute_batch`` for ``cursor.executemany()`` calls performed by the :class:`.Engine`. It is currently experimental but may well become True by default as it is critical for executemany performance. .. seealso:: :ref:`psycopg2_batch_mode` 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") .. seealso:: `PQconnectdbParams \ <http://www.postgresql.org/docs/9.1/static/libpq-connect.html#LIBPQ-PQCONNECTDBPARAMS>`_ Empty DSN Connections / Environment Variable Connections --------------------------------------------------------- The psycopg2 DBAPI can connect to PostgreSQL by passing an empty DSN to the libpq client library, which by default indicates to connect to a localhost PostgreSQL database that is open for "trust" connections. This behavior can be further tailored using a particular set of environment variables which are prefixed with ``PG_...``, which are consumed by ``libpq`` to take the place of any or all elements of the connection string. For this form, the URL can be passed without any elements other than the initial scheme:: engine = create_engine('postgresql+psycopg2://') In the above form, a blank "dsn" string is passed to the ``psycopg2.connect()`` function which in turn represents an empty DSN passed to libpq. .. versionadded:: 1.3.2 support for parameter-less connections with psycopg2. .. seealso:: `Environment Variables\ <https://www.postgresql.org/docs/current/libpq-envars.html>`_ - PostgreSQL documentation on how to use ``PG_...`` environment variables for connections. .. _psycopg2_execution_options: 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. * ``max_row_buffer`` - when using ``stream_results``, an integer value that specifies the maximum number of rows to buffer at a time. This is interpreted by the :class:`.BufferedRowResultProxy`, and if omitted the buffer will grow to ultimately store 1000 rows at a time. .. versionadded:: 1.0.6 .. _psycopg2_batch_mode: Psycopg2 Batch Mode (Fast Execution) ------------------------------------ Modern versions of psycopg2 include a feature known as `Fast Execution Helpers \ <http://initd.org/psycopg/docs/extras.html#fast-execution-helpers>`_, which have been shown in benchmarking to improve psycopg2's executemany() performance with INSERTS by multiple orders of magnitude. SQLAlchemy allows this extension to be used for all ``executemany()`` style calls invoked by an :class:`.Engine` when used with :ref:`multiple parameter sets <execute_multiple>`, by adding the ``use_batch_mode`` flag to :func:`.create_engine`:: engine = create_engine( "postgresql+psycopg2://scott:tiger@host/dbname", use_batch_mode=True) Batch mode is considered to be **experimental** at this time, however may be enabled by default in a future release. .. seealso:: :ref:`execute_multiple` - demonstrates how to use DBAPI ``executemany()`` with the :class:`.Connection` object. .. versionadded:: 1.2.0 .. _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:: 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. Bound Parameter Styles ---------------------- The default parameter style for the psycopg2 dialect is "pyformat", where SQL is rendered using ``%(paramname)s`` style. This format has the limitation that it does not accommodate the unusual case of parameter names that actually contain percent or parenthesis symbols; as SQLAlchemy in many cases generates bound parameter names based on the name of a column, the presence of these characters in a column name can lead to problems. There are two solutions to the issue of a :class:`.schema.Column` that contains one of these characters in its name. One is to specify the :paramref:`.schema.Column.key` for columns that have such names:: measurement = Table('measurement', metadata, Column('Size (meters)', Integer, key='size_meters') ) Above, an INSERT statement such as ``measurement.insert()`` will use ``size_meters`` as the parameter name, and a SQL expression such as ``measurement.c.size_meters > 10`` will derive the bound parameter name from the ``size_meters`` key as well. .. versionchanged:: 1.0.0 - SQL expressions will use :attr:`.Column.key` as the source of naming when anonymous bound parameters are created in SQL expressions; previously, this behavior only applied to :meth:`.Table.insert` and :meth:`.Table.update` parameter names. The other solution is to use a positional format; psycopg2 allows use of the "format" paramstyle, which can be passed to :paramref:`.create_engine.paramstyle`:: engine = create_engine( 'postgresql://scott:tiger@localhost:5432/test', paramstyle='format') With the above engine, instead of a statement like:: INSERT INTO measurement ("Size (meters)") VALUES (%(Size (meters))s) {'Size (meters)': 1} we instead see:: INSERT INTO measurement ("Size (meters)") VALUES (%s) (1, ) Where above, the dictionary style is converted into a tuple with positional style. 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`` .. 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. When this logger is set to the ``logging.INFO`` level, notice messages will be logged:: import logging logging.getLogger('sqlalchemy.dialects.postgresql').setLevel(logging.INFO) Above, it is assumed that logging is configured externally. If this is not the case, configuration such as ``logging.basicConfig()`` must be utilized:: import logging logging.basicConfig() # log messages to stdout logging.getLogger('sqlalchemy.dialects.postgresql').setLevel(logging.INFO) .. seealso:: `Logging HOWTO <https://docs.python.org/3/howto/logging.html>`_ - on the python.org website .. _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 psycopg2 version 2.4 or greater is used, and 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. This function is **skipped** if the version of psycopg2 installed is less than version 2.4. 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. """ # noqa from __future__ import absolute_import import decimal import logging import re from .base import _DECIMAL_TYPES from .base import _FLOAT_TYPES from .base import _INT_TYPES from .base import ENUM from .base import PGCompiler from .base import PGDialect from .base import PGExecutionContext from .base import PGIdentifierPreparer from .base import UUID from .hstore import HSTORE from .json import JSON from .json import JSONB from ... import exc from ... import processors from ... import types as sqltypes from ... import util from ...engine import result as _result from ...util import collections_abc try: from uuid import UUID as _python_UUID # noqa except ImportError: _python_UUID = None 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._expect_unicode is True: # for py2k, if the enum type needs unicode data (which is set up as # part of the Enum() constructor based on values passed as py2k # unicode objects) we have to use our own converters since # psycopg2's don't work, a rare exception to the "modern DBAPIs # support unicode everywhere" theme of deprecating # convert_unicode=True. Use the special "force_nocheck" directive # which forces unicode conversion to happen on the Python side # without an isinstance() check. in py3k psycopg2 does the right # thing automatically. self._expect_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) class _PGJSONB(JSONB): def result_processor(self, dialect, coltype): if dialect._has_native_jsonb: return None else: return super(_PGJSONB, self).result_processor(dialect, coltype) class _PGUUID(UUID): def bind_processor(self, dialect): if not self.as_uuid and dialect.use_native_uuid: def process(value): if value is not None: value = _python_UUID(value) return value return process def result_processor(self, dialect, coltype): if not self.as_uuid and dialect.use_native_uuid: def process(value): if value is not None: value = str(value) return value return process _server_side_id = util.counter() class PGExecutionContext_psycopg2(PGExecutionContext): def create_server_side_cursor(self): # 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) def get_result_proxy(self): self._log_notices(self.cursor) if self._is_server_side: return _result.BufferedRowResultProxy(self) else: return _result.ResultProxy(self) def _log_notices(self, cursor): # check also that notices is an iterable, after it's already # established that we will be iterating through it. This is to get # around test suites such as SQLAlchemy's using a Mock object for # cursor if not cursor.connection.notices or not isinstance( cursor.connection.notices, collections_abc.Iterable ): return 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): pass class PGIdentifierPreparer_psycopg2(PGIdentifierPreparer): pass class PGDialect_psycopg2(PGDialect): driver = "psycopg2" if util.py2k: supports_unicode_statements = False supports_server_side_cursors = True 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) FEATURE_VERSION_MAP = dict( native_json=(2, 5), native_jsonb=(2, 5, 4), sane_multi_rowcount=(2, 0, 9), array_oid=(2, 4, 3), hstore_adapter=(2, 4), ) _has_native_hstore = False _has_native_json = False _has_native_jsonb = False engine_config_types = PGDialect.engine_config_types.union( [("use_native_unicode", util.asbool)] ) colspecs = util.update_copy( PGDialect.colspecs, { sqltypes.Numeric: _PGNumeric, ENUM: _PGEnum, # needs force_unicode sqltypes.Enum: _PGEnum, # needs force_unicode HSTORE: _PGHStore, JSON: _PGJSON, sqltypes.JSON: _PGJSON, JSONB: _PGJSONB, UUID: _PGUUID, }, ) def __init__( self, server_side_cursors=False, use_native_unicode=True, client_encoding=None, use_native_hstore=True, use_native_uuid=True, use_batch_mode=False, **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.use_native_uuid = use_native_uuid self.supports_unicode_binds = use_native_unicode self.client_encoding = client_encoding self.psycopg2_batch_mode = use_batch_mode 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 >= self.FEATURE_VERSION_MAP["native_json"] ) self._has_native_jsonb = ( self.psycopg2_version >= self.FEATURE_VERSION_MAP["native_jsonb"] ) # http://initd.org/psycopg/docs/news.html#what-s-new-in-psycopg-2-0-9 self.supports_sane_multi_rowcount = ( self.psycopg2_version >= self.FEATURE_VERSION_MAP["sane_multi_rowcount"] and not self.psycopg2_batch_mode ) @classmethod def dbapi(cls): import psycopg2 return psycopg2 @classmethod def _psycopg2_extensions(cls): from psycopg2 import extensions return extensions @classmethod def _psycopg2_extras(cls): from psycopg2 import extras return extras @util.memoized_property def _isolation_lookup(self): extensions = self._psycopg2_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): extras = self._psycopg2_extras() extensions = self._psycopg2_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_uuid: def on_connect(conn): extras.register_uuid(None, conn) 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 kw = {"oid": oid} if util.py2k: kw["unicode"] = True if ( self.psycopg2_version >= self.FEATURE_VERSION_MAP["array_oid"] ): kw["array_oid"] = array_oid extras.register_hstore(conn, **kw) fns.append(on_connect) if self.dbapi and self._json_deserializer: def on_connect(conn): if self._has_native_json: extras.register_default_json( conn, loads=self._json_deserializer ) if self._has_native_jsonb: extras.register_default_jsonb( 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 def do_executemany(self, cursor, statement, parameters, context=None): if self.psycopg2_batch_mode: extras = self._psycopg2_extras() extras.execute_batch(cursor, statement, parameters) else: cursor.executemany(statement, parameters) @util.memoized_instancemethod def _hstore_oids(self, conn): if self.psycopg2_version >= self.FEATURE_VERSION_MAP["hstore_adapter"]: extras = self._psycopg2_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 opts: if "port" in opts: opts["port"] = int(opts["port"]) opts.update(url.query) # send individual dbname, user, password, host, port # parameters to psycopg2.connect() return ([], opts) elif url.query: # any other connection arguments, pass directly opts.update(url.query) return ([], opts) else: # no connection arguments whatsoever; psycopg2.connect() # requires that "dsn" be present as a blank string. 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", "SSL error: decryption failed or bad record mac", "SSL SYSCALL error: Operation timed out", ]: idx = str_e.find(msg) if idx >= 0 and '"' not in str_e[:idx]: return True return False dialect = PGDialect_psycopg2