使用 sqlalchemy create_engine 配置查询/命令超时？答案

【问题标题】：Configure query/command timeout with sqlalchemy create_engine?使用 sqlalchemy create_engine 配置查询/命令超时？
【发布时间】：2017-12-09 17:31:36
【问题描述】：

以下 Python 代码 sn-p 说明了这个问题：

print("starting")

# I am trying to configure a query/command timeout of one second.
# sqlalchemy docs suggest execution_options but the documented list of options doesn't include a timeout:
# http://docs.sqlalchemy.org/en/latest/core/connections.html#sqlalchemy.engine.Connection.execution_options
# Below, I am guessing at several likely timeout parameter names:
db_engine = create_engine("postgresql://user:pass@server/catalog",
                          execution_options={"timeout": 1.0,
                                             "statement_timeout": 1.0,
                                             "query_timeout": 1.0,
                                             "execution_timeout": 1.0})

with db_engine.connect() as db_connection:
    print("got db_connection")

    # Artificially force a two second query time with pg_sleep.
    # This is designed to guarantee timeout conditions and trigger an exception.
    result_proxy = db_connection.execute("SELECT pg_sleep(2);")

    # If the timeout worked, this statement will not execute.
    # Currently, it does execute, which means my timeout isn't working.
    print("Query successfully complete. Got result_proxy")

【问题讨论】：

标签： python postgresql sqlalchemy

【解决方案1】：

您可以通过options parameter in libpq 设置statement_timeout 等配置值。作为connect 调用的一部分，您可以在psycopg2 中访问此参数。您可以通过 connect_args 参数从 SQLAlchemy 将其他参数传递给 connect 调用。所以，把它们放在一起：

engine = create_engine(..., connect_args={"options": "-c statement_timeout=1000"})

【讨论】：

我不能用 mysql 做到这一点。我在 mysql 文档中找不到关于语句超时的任何地方。
@Dilip MySQL 的功能更加有限，但最接近的等价物（仅适用于只读SELECT 语句）是max_execution_time。

【解决方案2】：

我花了一些时间才弄清楚如何使用 create_engine(...) 设置多个选项。以防万一，您也在寻找相同的 -

engine = create_engine(..., connect_args={'options': '-c lock_timeout=3000 -c statement_timeout=3000'})

【讨论】：