在运行python脚本从cassandradb检索记录时，会收到警告消息，如“最后一个错误：没有到主机的路由”以及70k条记录花费的时间超过1分钟
在cassandradb中，select查询结果在3秒内给出。但是python脚本花费了超过1分50秒的时间，并给出了如下警告

OSError: [Errno 113] Tried connecting to [('10.184.20.196', 9042)]. Last error: No route to host
WARNING:cassandra.cluster:Host 10.184.20.196 has been marked down
WARNING:cassandra.pool:Error attempting to reconnect to 10.114.20.126, scheduling retry in 2.0 seconds: [Errno 113] Tried connecting to [('10.114.20.126', 9042)]. Last error: No route to host

WARNING:cassandra.pool:Error attempting to reconnect to 10.114.20.126, scheduling retry in 4.0 seconds: [Errno 113] Tried connecting to [('10.114.20.126', 9042)]. Last error: No route to host

WARNING:cassandra.pool:Error attempting to reconnect to 
10.114.20.126, scheduling retry in 16.0 seconds: [Errno 113] Tried connecting to [('10.114.20.126', 9042)]. Last error: No route to host

INFO:werkzeug:169.144.102.112 - - [27/Aug/2019 22:10:05] "GET /fso/sitedb?circle=MP&lat=25.4248&long=77.6555&rad=1 HTTP/1.1" 200 -

WARNING:cassandra.pool:Error attempting to reconnect to 10.114.20.126, scheduling retry in 64.0 seconds: [Errno 113] Tried connecting to [('10.114.20.126', 9042)]. Last error: No route to host