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Avatica client can not talk to Multiple Avatica Servers issue


Hi, 

Our query engine is using calcite as parser/optimizer and enumerable as runtime if needed to federate different storage engines. We are trying to enable JDBC access to our query engine. Everything works smoothly when we only have one calcite/avatica server.

However, JDBC calls will fail if we run multiple instances of calcite/avatica servers behind a generic load-balancer. Given that JDBC server is not stateless, this problem was not a surprise. I searched around and here are the two options suggested by phoenix developers (https://community.hortonworks.com/articles/9377/deploying-the-phoenix-query-server-in-production-e.html <https://community.hortonworks.com/articles/9377/deploying-the-phoenix-query-server-in-production-e.html>):
1. sticky sessions: make the router to always route a client to a given server. 
2. client-driven routing: implementing Avarice’s protocol which passes an identifier to the load balancer to control how the request is routed to the backend servers.

Before we rush into any implementation, we would really appreciate it if anyone can share experience or thoughts regarding this issue. Thanks,

-Jiandan