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![James Salter](/assets/img/avatar_default.png)
Support a unified search query syntax which leverages more of the full-text search of each database supported by Synapse. Supports, with the same syntax across Postgresql 11+ and Sqlite: - quoted "search terms" - `AND`, `OR`, `-` (negation) operators - Matching words based on their stem, e.g. searches for "dog" matches documents containing "dogs". This is achieved by - If on postgresql 11+, pass the user input to `websearch_to_tsquery` - If on sqlite, manually parse the query and transform it into the sqlite-specific query syntax. Note that postgresql 10, which is close to end-of-life, falls back to using `phraseto_tsquery`, which only supports a subset of the features. Multiple terms separated by a space are implicitly ANDed. Note that: 1. There is no escaping of full-text syntax that might be supported by the database; e.g. `NOT`, `NEAR`, `*` in sqlite. This runs the risk that people might discover this as accidental functionality and depend on something we don't guarantee. 2. English text is assumed for stemming. To support other languages, either the target language needs to be known at the time of indexing the message (via room metadata, or otherwise), or a separate index for each language supported could be created. Sqlite docs: https://www.sqlite.org/fts3.html#full_text_index_queries Postgres docs: https://www.postgresql.org/docs/11/textsearch-controls.html
241 lines
9.3 KiB
Python
241 lines
9.3 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(
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BaseDatabaseEngine[psycopg2.extensions.connection, psycopg2.extensions.cursor]
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):
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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 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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@property
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def tsquery_func(self) -> str:
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"""
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Selects a tsquery_* func to use.
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Ref: https://www.postgresql.org/docs/current/textsearch-controls.html
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Returns:
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The function name.
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"""
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# Postgres 11 added support for websearch_to_tsquery.
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assert self._version is not None
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if self._version >= 110000:
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return "websearch_to_tsquery"
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return "plainto_tsquery"
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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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@staticmethod
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def executescript(cursor: psycopg2.extensions.cursor, script: str) -> None:
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"""Execute a chunk of SQL containing multiple semicolon-delimited statements.
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Psycopg2 seems happy to do this in DBAPI2's `execute()` function.
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"""
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cursor.execute(script)
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