We are currently using CDH 5.9.x and Impala connected via Tableau to serve requests to clients. But we would like to add few additional filters to each and every query coming from Tableau to Impala.
Is it possible to write plugins / filters in Impala (just like Servlet filters) which would intercept request and modify the query before sending it across to the Impala daemon? If not, is there any feature which can be used for pre-request processing in Impala?
I'm afraid Impala doesn't have such a feature. Perhaps you might be able to address your use case with views and/or user-defined functions (that you can use as part of WHERE filters)?