conditionally import sqlite and postgres in engines/__init__.py

2 files changed, 6 insertions, 3 deletions

diff --git a/synapse/storage/engines/__init__.py b/synapse/storage/engines/__init__.py

index f51b3d228e..6b0024c611 100644
--- a/synapse/storage/engines/__init__.py
+++ b/synapse/storage/engines/__init__.py
@@ -14,17 +14,19 @@
 from typing import Any, Mapping
 
 from ._base import BaseDatabaseEngine, IncorrectDatabaseSetup
-from .postgres import PostgresEngine
-from .sqlite import Sqlite3Engine
 
 
 def create_engine(database_config: Mapping[str, Any]) -> BaseDatabaseEngine:
     name = database_config["name"]
 
     if name == "sqlite3":
+        from .sqlite import Sqlite3Engine
+
         return Sqlite3Engine(database_config)
 
     if name == "psycopg2":
+        from .postgres import PostgresEngine
+
         return PostgresEngine(database_config)
 
     raise RuntimeError("Unsupported database engine '%s'" % (name,))
diff --git a/synapse/storage/engines/postgres.py b/synapse/storage/engines/postgres.py

index 391f8ed24a..7b5dc4413b 100644
--- a/synapse/storage/engines/postgres.py
+++ b/synapse/storage/engines/postgres.py
@@ -15,6 +15,8 @@
 import logging
 from typing import TYPE_CHECKING, Any, Mapping, NoReturn, Optional, Tuple, cast
 
+import psycopg2
+
 from synapse.storage.engines._base import (
     BaseDatabaseEngine,
     IncorrectDatabaseSetup,
@@ -23,7 +25,6 @@ from synapse.storage.engines._base import (
 from synapse.storage.types import Cursor
 
 if TYPE_CHECKING:
-    import psycopg2  # noqa: F401
 
     from synapse.storage.database import LoggingDatabaseConnection