222 lines
		
	
	
		
			8.7 KiB
		
	
	
	
		
			Python
		
	
	
			
		
		
	
	
			222 lines
		
	
	
		
			8.7 KiB
		
	
	
	
		
			Python
		
	
	
# Copyright 2015, 2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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#     http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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from typing import TYPE_CHECKING, Any, Mapping, NoReturn, Optional, Tuple, cast
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import psycopg2.extensions
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from synapse.storage.engines._base import (
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    BaseDatabaseEngine,
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    IncorrectDatabaseSetup,
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    IsolationLevel,
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)
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from synapse.storage.types import Cursor
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if TYPE_CHECKING:
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    from synapse.storage.database import LoggingDatabaseConnection
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logger = logging.getLogger(__name__)
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class PostgresEngine(BaseDatabaseEngine[psycopg2.extensions.connection]):
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    def __init__(self, database_config: Mapping[str, Any]):
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        super().__init__(psycopg2, database_config)
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        psycopg2.extensions.register_type(psycopg2.extensions.UNICODE)
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        # Disables passing `bytes` to txn.execute, c.f. #6186. If you do
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        # actually want to use bytes than wrap it in `bytearray`.
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        def _disable_bytes_adapter(_: bytes) -> NoReturn:
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            raise Exception("Passing bytes to DB is disabled.")
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        psycopg2.extensions.register_adapter(bytes, _disable_bytes_adapter)
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        self.synchronous_commit: bool = database_config.get("synchronous_commit", True)
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        self._version: Optional[int] = None  # unknown as yet
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        self.isolation_level_map: Mapping[int, int] = {
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            IsolationLevel.READ_COMMITTED: psycopg2.extensions.ISOLATION_LEVEL_READ_COMMITTED,
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            IsolationLevel.REPEATABLE_READ: psycopg2.extensions.ISOLATION_LEVEL_REPEATABLE_READ,
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            IsolationLevel.SERIALIZABLE: psycopg2.extensions.ISOLATION_LEVEL_SERIALIZABLE,
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        }
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        self.default_isolation_level = (
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            psycopg2.extensions.ISOLATION_LEVEL_REPEATABLE_READ
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        )
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        self.config = database_config
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    @property
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    def single_threaded(self) -> bool:
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        return False
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    def get_db_locale(self, txn: Cursor) -> Tuple[str, str]:
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        txn.execute(
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            "SELECT datcollate, datctype FROM pg_database WHERE datname = current_database()"
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        )
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        collation, ctype = cast(Tuple[str, str], txn.fetchone())
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        return collation, ctype
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    def check_database(
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        self,
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        db_conn: psycopg2.extensions.connection,
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        allow_outdated_version: bool = False,
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    ) -> None:
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        # Get the version of PostgreSQL that we're using. As per the psycopg2
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        # docs: The number is formed by converting the major, minor, and
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        # revision numbers into two-decimal-digit numbers and appending them
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        # together. For example, version 8.1.5 will be returned as 80105
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        self._version = cast(int, db_conn.server_version)
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        allow_unsafe_locale = self.config.get("allow_unsafe_locale", False)
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        # Are we on a supported PostgreSQL version?
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        if not allow_outdated_version and self._version < 100000:
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            raise RuntimeError("Synapse requires PostgreSQL 10 or above.")
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        with db_conn.cursor() as txn:
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            txn.execute("SHOW SERVER_ENCODING")
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            rows = txn.fetchall()
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            if rows and rows[0][0] != "UTF8":
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                raise IncorrectDatabaseSetup(
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                    "Database has incorrect encoding: '%s' instead of 'UTF8'\n"
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                    "See docs/postgres.md for more information." % (rows[0][0],)
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                )
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            collation, ctype = self.get_db_locale(txn)
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            if collation != "C":
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                logger.warning(
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                    "Database has incorrect collation of %r. Should be 'C'",
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                    collation,
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                )
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                if not allow_unsafe_locale:
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                    raise IncorrectDatabaseSetup(
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                        "Database has incorrect collation of %r. Should be 'C'\n"
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                        "See docs/postgres.md for more information. You can override this check by"
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                        "setting 'allow_unsafe_locale' to true in the database config.",
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                        collation,
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                    )
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            if ctype != "C":
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                if not allow_unsafe_locale:
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                    logger.warning(
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                        "Database has incorrect ctype of %r. Should be 'C'",
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                        ctype,
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                    )
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                    raise IncorrectDatabaseSetup(
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                        "Database has incorrect ctype of %r. Should be 'C'\n"
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                        "See docs/postgres.md for more information. You can override this check by"
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                        "setting 'allow_unsafe_locale' to true in the database config.",
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                        ctype,
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                    )
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    def check_new_database(self, txn: Cursor) -> None:
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        """Gets called when setting up a brand new database. This allows us to
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        apply stricter checks on new databases versus existing database.
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        """
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        collation, ctype = self.get_db_locale(txn)
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        errors = []
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        if collation != "C":
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            errors.append("    - 'COLLATE' is set to %r. Should be 'C'" % (collation,))
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        if ctype != "C":
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            errors.append("    - 'CTYPE' is set to %r. Should be 'C'" % (ctype,))
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        if errors:
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            raise IncorrectDatabaseSetup(
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                "Database is incorrectly configured:\n\n%s\n\n"
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                "See docs/postgres.md for more information." % ("\n".join(errors))
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            )
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    def convert_param_style(self, sql: str) -> str:
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        return sql.replace("?", "%s")
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    def on_new_connection(self, db_conn: "LoggingDatabaseConnection") -> None:
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        db_conn.set_isolation_level(self.default_isolation_level)
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        # Set the bytea output to escape, vs the default of hex
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        cursor = db_conn.cursor()
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        cursor.execute("SET bytea_output TO escape")
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        # Asynchronous commit, don't wait for the server to call fsync before
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        # ending the transaction.
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        # https://www.postgresql.org/docs/current/static/wal-async-commit.html
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        if not self.synchronous_commit:
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            cursor.execute("SET synchronous_commit TO OFF")
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        cursor.close()
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        db_conn.commit()
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    @property
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    def can_native_upsert(self) -> bool:
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        """
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        Can we use native UPSERTs?
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        """
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        return True
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    @property
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    def supports_using_any_list(self) -> bool:
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        """Do we support using `a = ANY(?)` and passing a list"""
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        return True
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    @property
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    def supports_returning(self) -> bool:
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        """Do we support the `RETURNING` clause in insert/update/delete?"""
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        return True
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    def is_deadlock(self, error: Exception) -> bool:
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        if isinstance(error, psycopg2.DatabaseError):
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            # https://www.postgresql.org/docs/current/static/errcodes-appendix.html
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            # "40001" serialization_failure
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            # "40P01" deadlock_detected
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            return error.pgcode in ["40001", "40P01"]
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        return False
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    def is_connection_closed(self, conn: psycopg2.extensions.connection) -> bool:
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        return bool(conn.closed)
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    def lock_table(self, txn: Cursor, table: str) -> None:
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        txn.execute("LOCK TABLE %s in EXCLUSIVE MODE" % (table,))
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    @property
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    def server_version(self) -> str:
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        """Returns a string giving the server version. For example: '8.1.5'."""
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        # note that this is a bit of a hack because it relies on check_database
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        # having been called. Still, that should be a safe bet here.
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        numver = self._version
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        assert numver is not None
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        # https://www.postgresql.org/docs/current/libpq-status.html#LIBPQ-PQSERVERVERSION
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        if numver >= 100000:
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            return "%i.%i" % (numver / 10000, numver % 10000)
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        else:
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            return "%i.%i.%i" % (numver / 10000, (numver % 10000) / 100, numver % 100)
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    def in_transaction(self, conn: psycopg2.extensions.connection) -> bool:
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        return conn.status != psycopg2.extensions.STATUS_READY
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    def attempt_to_set_autocommit(
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        self, conn: psycopg2.extensions.connection, autocommit: bool
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    ) -> None:
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        return conn.set_session(autocommit=autocommit)
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    def attempt_to_set_isolation_level(
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        self, conn: psycopg2.extensions.connection, isolation_level: Optional[int]
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    ) -> None:
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        if isolation_level is None:
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            isolation_level = self.default_isolation_level
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        else:
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            isolation_level = self.isolation_level_map[isolation_level]
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        return conn.set_isolation_level(isolation_level)
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