带多个仓位的图解分离

from sqlalchemy import create_engine, Table, Column, Integer, String, MetaData
from sqlalchemy.orm import sessionmaker

# 创建多个数据库连接
db_shards = {
    'shard1': create_engine('postgresql://user:password@shard1_host/dbname'),
    'shard2': create_engine('postgresql://user:password@shard2_host/dbname'),
    'shard3': create_engine('postgresql://user:password@shard3_host/dbname')
}

# 定义表结构
metadata = MetaData()
orders = Table('orders', metadata,
                Column('id', Integer, primary_key=True),
                Column('user_id', Integer),
                Column('amount', Integer))

# 创建表
for shard_name, engine in db_shards.items():
    metadata.create_all(engine)

# 插入数据
def insert_order(user_id, amount):
    shard_key = hash(user_id) % len(db_shards)
    shard_name = list(db_shards.keys())[shard_key]
    engine = db_shards[shard_name]
    Session = sessionmaker(bind=engine)
    session = Session()
    ins = orders.insert().values(user_id=user_id, amount=amount)
    session.execute(ins)
    session.commit()

# 查询数据
def get_orders_by_user(user_id):
    shard_key = hash(user_id) % len(db_shards)
    shard_name = list(db_shards.keys())[shard_key]
    engine = db_shards[shard_name]
    Session = sessionmaker(bind=engine)
    session = Session()
    result = session.query(orders).filter_by(user_id=user_id).all()
    return result