Do not always start a db txn on Postgres (#14840)

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Andrew Morgan 2023-02-09 19:57:01 +00:00 committed by GitHub
parent 218a383c43
commit c1d2ce2901
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2 changed files with 10 additions and 4 deletions

1
changelog.d/14840.misc Normal file
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@ -0,0 +1 @@
Prevent "WARNING: there is already a transaction in progress" lines appearing in PostgreSQL's logs on some occasions.

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@ -23,7 +23,7 @@ from typing_extensions import Counter as CounterType
from synapse.config.homeserver import HomeServerConfig
from synapse.storage.database import LoggingDatabaseConnection
from synapse.storage.engines import BaseDatabaseEngine, PostgresEngine
from synapse.storage.engines import BaseDatabaseEngine, PostgresEngine, Sqlite3Engine
from synapse.storage.schema import SCHEMA_COMPAT_VERSION, SCHEMA_VERSION
from synapse.storage.types import Cursor
@ -108,9 +108,14 @@ def prepare_database(
# so we start one before running anything. This ensures that any upgrades
# are either applied completely, or not at all.
#
# (psycopg2 automatically starts a transaction as soon as we run any statements
# at all, so this is redundant but harmless there.)
cur.execute("BEGIN TRANSACTION")
# psycopg2 does not automatically start transactions when in autocommit mode.
# While it is technically harmless to nest transactions in postgres, doing so
# results in a warning in Postgres' logs per query. And we'd rather like to
# avoid doing that.
if isinstance(database_engine, Sqlite3Engine) or (
isinstance(database_engine, PostgresEngine) and db_conn.autocommit
):
cur.execute("BEGIN TRANSACTION")
logger.info("%r: Checking existing schema version", databases)
version_info = _get_or_create_schema_state(cur, database_engine)