Impala UDFs have the following limitations:
- Impala cannot work with UDFs that accept or return composite,
nested, or types not available in Impala tables.
- UDFs must produce the same output each time the same argument
value is passed.
- UDFs cannot spawn other threads or processes.
- UDFs become undefined when you restart the catalogd process. In
this scenario, you must reload the UDFs.
- You currently cannot include user-defined table functions in
Impala queries.