@sivakumar sudhakarannair girijakumari
If you want the function to be available globally, across multiple sessions, you need to create a permanent function,e.g.
create function ST_AsText as 'com.esri.hadoop.hive.ST_AsText';
You should issue "create function" statements via a global script. Assuming that you modified a function, in order to recreate it, you would need first to drop it. This script should be executed as part of Hive service start/restart such that functions will still be available.
drop function ST_AsText as 'com.esri.hadoop.hive.ST_AsText';