Question

我想尝试一下板条箱。我首先尝试通过成功加载一些Twitter数据和从管理用户界面进行查询来进行尝试。但是，当我尝试使用SQLAlchemy进行查询时，出现以下错误。

OperationalError: (crate.client.exceptions.ConnectionError) 
No more Servers available, exception from last server: HTTPConnectionPool(host='localhost', port=4200): 
Max retries exceeded with url: 
/_sql (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f51485b2c18>:
Failed to establish a new connection: [Errno 111] Connection refused'))

[SQL: SELECT * FROM tweets LIMIT 100; ]

(Background on this error at: http://sqlalche.me/e/e3q8)

这是我运行的导致错误的代码。

from crate import client
import sqlalchemy as sa
import pandas as pd

engine = sa.create_engine('crate://localhost:4200')
query = (
            "SELECT * "
            "FROM tweets "
            "LIMIT 100; "
    )
df = pd.read_sql(query, engine)

有什么办法解决（设置均为默认设置）吗？

更新：

Crate在主机系统上运行，而Jupyter在同一台计算机上的容器中运行。我可以通过主机上的“ http://localhost:4200”访问“板条箱”，但是不能从同一环境中的其他计算机上访问“ http://xxx.xxx.xxx.xxx:4200”。

我都尝试过

engine = sa.create_engine('crate://10.7.116.222:4200')
engine = sa.create_engine('crate://')

导致相同错误的

Removed server http://127.0.0.1:4200 from active pool
Removed server http://127.0.0.1:4200 from active pool

OperationalError: (crate.client.exceptions.ConnectionError) 
No more Servers available, exception from last server: 
HTTPConnectionPool(host='127.0.0.1', port=4200): 
Max retries exceeded with url: 
/_sql (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f5147faaa58>: 
Failed to establish a new connection: [Errno 111] Connection refused'))
[SQL: SELECT * FROM tweets LIMIT 10; ]
(Background on this error at: http://sqlalche.me/e/e3q8)

Answer 1

我还没有尝试过，但是根据documentation'localhost：4200'的假设，您可以仅使用engine = sa.create_engine('crate://')进行连接

通过SQLAlchemy方言查询板条箱数据库：没有更多可用的服务器

1 个答案: