diff --git a/synapse/storage/engines/_base.py b/synapse/storage/engines/_base.py
index ec5a4d198b..ab0bbe4bd3 100644
--- a/synapse/storage/engines/_base.py
+++ b/synapse/storage/engines/_base.py
@@ -12,7 +12,94 @@
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
+import abc
+from typing import Generic, TypeVar
+
+from synapse.storage.types import Connection
class IncorrectDatabaseSetup(RuntimeError):
pass
+
+
+ConnectionType = TypeVar("ConnectionType", bound=Connection)
+
+
+class BaseDatabaseEngine(Generic[ConnectionType], metaclass=abc.ABCMeta):
+ def __init__(self, module, database_config: dict):
+ self.module = module
+
+ @property
+ @abc.abstractmethod
+ def single_threaded(self) -> bool:
+ ...
+
+ @property
+ @abc.abstractmethod
+ def can_native_upsert(self) -> bool:
+ """
+ Do we support native UPSERTs?
+ """
+ ...
+
+ @property
+ @abc.abstractmethod
+ def supports_tuple_comparison(self) -> bool:
+ """
+ Do we support comparing tuples, i.e. `(a, b) > (c, d)`?
+ """
+ ...
+
+ @property
+ @abc.abstractmethod
+ def supports_using_any_list(self) -> bool:
+ """
+ Do we support using `a = ANY(?)` and passing a list
+ """
+ ...
+
+ @abc.abstractmethod
+ def check_database(
+ self, db_conn: ConnectionType, allow_outdated_version: bool = False
+ ) -> None:
+ ...
+
+ @abc.abstractmethod
+ def check_new_database(self, txn) -> None:
+ """Gets called when setting up a brand new database. This allows us to
+ apply stricter checks on new databases versus existing database.
+ """
+ ...
+
+ @abc.abstractmethod
+ def convert_param_style(self, sql: str) -> str:
+ ...
+
+ @abc.abstractmethod
+ def on_new_connection(self, db_conn: ConnectionType) -> None:
+ ...
+
+ @abc.abstractmethod
+ def is_deadlock(self, error: Exception) -> bool:
+ ...
+
+ @abc.abstractmethod
+ def is_connection_closed(self, conn: ConnectionType) -> bool:
+ ...
+
+ @abc.abstractmethod
+ def lock_table(self, txn, table: str) -> None:
+ ...
+
+ @abc.abstractmethod
+ def get_next_state_group_id(self, txn) -> int:
+ """Returns an int that can be used as a new state_group ID
+ """
+ ...
+
+ @property
+ @abc.abstractmethod
+ def server_version(self) -> str:
+ """Gets a string giving the server version. For example: '3.22.0'
+ """
+ ...
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