Questions about the command query's influences for later queries?

[liushaohui <li...@xiaomi.com>]

Hi all,

Lens is very interesting project and I am trying to use it in an inner 
OLAP project to route different queries to different engines: Hive, 
SparkSQL and kylin.

When read the code, I encountered a question about the previous query's 
influences about later queries?

For an example, there are 2 queries in a session. The first query is  a 
command of creating a temporary function and the second the a select 
query using the function.

Is there a mechanism to make sure that the two queries are routed to the 
same backend driver? Or each driver can get the command?

And there are same questions for other commands like: setting a conf and 
creating a temporary view.

Thanks

-Shaohui Liu