如何在更短的时间内将数百万条记录从客户端数据库导入到我的数据库中

from sqlalchemy import create_engine, Table, MetaData
from sqlalchemy.orm import sessionmaker
import pandas as pd

# 假设客户端数据库为SQLite，目标数据库为PostgreSQL
client_engine = create_engine('sqlite:///client.db')
target_engine = create_engine('postgresql://user:password@host/dbname')

# 创建会话
Session = sessionmaker(bind=target_engine)
session = Session()

# 读取客户端数据库中的数据
metadata = MetaData(bind=client_engine)
source_table = Table('source_table', metadata, autoload_with=client_engine)
data = pd.read_sql(source_table.select(), client_engine)

# 禁用目标表的索引（如果支持）
with target_engine.connect() as conn:
    conn.execute('ALTER TABLE target_table DISABLE TRIGGER ALL;')  # PostgreSQL 特定命令
    conn.execute('ALTER INDEX ALL ON target_table DISABLE;')

# 批量插入数据
data.to_sql('target_table', target_engine, if_exists='append', index=False, chunksize=10000)

# 重新启用索引
with target_engine.connect() as conn:
    conn.execute('ALTER TABLE target_table ENABLE TRIGGER ALL;')
    conn.execute('ALTER INDEX ALL ON target_table ENABLE;')

session.commit()