fix: really use connection pooling

src/repository/common.py

@@ -8,19 +8,38 @@ import os
 
 load_dotenv()
 
+_engine = None
+_SessionLocal = None
+
 def get_engine():
-    database_url = os.getenv("DATABASE_URL")
-    if not database_url:
-        raise ValueError("DATABASE_URL is not set in environment variables")
-    return create_engine(database_url, pool_pre_ping=True)
+    global _engine
+    
+    if _engine is None:
+        # Load the database URL from environment variables
+        database_url = os.getenv("DATABASE_URL")
+        if not database_url:
+            raise ValueError("DATABASE_URL is not set in environment variables")
+        
+        # Create the SQLAlchemy engine
+        _engine = create_engine(database_url, pool_pre_ping=True)
+    
+    return _engine
+
+def get_session_local() -> sessionmaker:
+    global _SessionLocal
+
+    if _SessionLocal is None:
+        # Create a new session local
+        _SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=get_engine())
+    
+    return _SessionLocal
 
 @contextmanager
 def get_session() -> Generator[Session, None, None]:
     """
     Get a connection to the Postgres database
     """
-    engine = get_engine()
-    SessionLocal = sessionmaker(bind=engine)
+    SessionLocal = get_session_local()
     db = SessionLocal()
     try:
         yield db