In the following Impala doc, https://impala.apache.org/docs/build/html/topics/impala_proxy.html,
One of the setting is this:
server symbolic_name_5 impala-host-1.example.com:21050
The above setting is used to allow sticky sessions for Impalad. However, when that Impalad goes down, any subsequent queries fail in the Hue session fails. In order for subsequent queries to run as expected, we require "check" option, which makes sure that the target is alive and if not, then redirect to another ImpalaD.
server symbolic_name_5 check impala-host-1.example.com:21050