表创建后如何在sqlalchemy中添加基本索引的困惑

from sqlalchemy import create_engine, Column, Integer, String, Index
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

engine = create_engine('数据库连接字符串')
Session = sessionmaker(bind=engine)
session = Session()

Base = declarative_base()

class MyTable(Base):
    __tablename__ = 'my_table'
    id = Column(Integer, primary_key=True)
    name = Column(String(50))

Base.metadata.create_all(engine)
index = Index('idx_name', MyTable.name)  # 创建名为'idx_name'的索引，索引列为'name'
index.create(engine)  # 在数据库中创建索引

query = session.query(MyTable).filter(MyTable.name == 'some_name').\
    order_by(MyTable.id).\
    options(Index('idx_name'))  # 使用索引
result = query.all()