fix: set default mysql isolation level to 'READ COMMITTED'

.gitattributes

@@ -1 +1,2 @@
 docker/**/*.sh text eol=lf
+*.svg binary

superset/config.py

@@ -196,12 +196,14 @@ def _try_json_readsha(filepath: str, length: int) -> str | None:
 # SQLALCHEMY_DATABASE_URI = 'mysql://myapp@localhost/myapp'
 # SQLALCHEMY_DATABASE_URI = 'postgresql://root:password@localhost/myapp'
 
-# The default MySQL isolation level is REPEATABLE READ whereas the default PostgreSQL
-# isolation level is READ COMMITTED. All backends should use READ COMMITTED (or similar)
-# to help ensure consistent behavior.
-SQLALCHEMY_ENGINE_OPTIONS = {
- "isolation_level": "SERIALIZABLE", # SQLite does not support READ COMMITTED.
-}
+# This config is exposed through flask-sqlalchemy, and can be used to set your metadata
+# database connection settings. You can use this to set arbitrary connection settings
+# that may be specific to the database engine you are using.
+# Note that you can use this to set the isolation level of your database, as in
+# `SQLALCHEMY_ENGINE_OPTIONS = {"isolation_level": "READ COMMITTED"}`
+# Also note that we recommend READ COMMITTED for regular operation.
+# Find out more here https://flask-sqlalchemy.palletsprojects.com/en/3.1.x/config/
+SQLALCHEMY_ENGINE_OPTIONS = {}
 
 # In order to hook up a custom password store for all SQLALCHEMY connections
 # implement a function that takes a single argument of type 'sqla.engine.url',

superset/initialization/__init__.py

@@ -32,6 +32,7 @@
 from werkzeug.middleware.proxy_fix import ProxyFix
 
 from superset.constants import CHANGE_ME_SECRET_KEY
+from superset.databases.utils import make_url_safe
 from superset.extensions import (
  _event_logger,
  APP_DIR,
@@ -482,12 +483,36 @@ def init_app(self) -> None:
  self.configure_wtf()
  self.configure_middlewares()
  self.configure_cache()
+ self.set_db_default_isolation()
 
  with self.superset_app.app_context():
  self.init_app_in_ctx()
 
  self.post_init()
 
+ def set_db_default_isolation(self) -> None:
+ # This block sets the default isolation level for mysql to READ COMMITTED if not
+ # specified in the config. You can set your isolation in the config by using
+ # SQLALCHEMY_ENGINE_OPTIONS
+ eng_options = self.config["SQLALCHEMY_ENGINE_OPTIONS"] or {}
+ isolation_level = eng_options.get("isolation_level")
+ set_isolation_level_to = None
+
+ if not isolation_level:
+ backend = make_url_safe(
+ self.config["SQLALCHEMY_DATABASE_URI"]
+ ).get_backend_name()
+ if backend in ("mysql", "postgresql"):
+ set_isolation_level_to = "READ COMMITTED"
+
+ if set_isolation_level_to:
+ logger.info(
+ "Setting database isolation level to %s",
+ set_isolation_level_to,
+ )
+ with self.superset_app.app_context():
+ db.engine.execution_options(isolation_level=set_isolation_level_to)
+
  def configure_auth_provider(self) -> None:
  machine_auth_provider_factory.init_app(self.superset_app)
 

tests/integration_tests/superset_test_config.py

@@ -59,9 +59,6 @@
  "removed in a future version of Superset."
  )
 
-if make_url(SQLALCHEMY_DATABASE_URI).get_backend_name() in ("postgresql", "mysql"):
- SQLALCHEMY_ENGINE_OPTIONS["isolation_level"] = "READ COMMITTED" # noqa: F405
-
 # Speeding up the tests.integration_tests.
 PRESTO_POLL_INTERVAL = 0.1
 HIVE_POLL_INTERVAL = 0.1

tests/integration_tests/superset_test_config_thumbnails.py

@@ -41,9 +41,6 @@
  in a future version of Superset."
  )
 
-if make_url(SQLALCHEMY_DATABASE_URI).get_backend_name() in ("postgresql", "mysql"):
- SQLALCHEMY_ENGINE_OPTIONS["isolation_level"] = "READ COMMITTED" # noqa: F405
-
 SQL_SELECT_AS_CTA = True
 SQL_MAX_ROW = 666