Okay, I'm writing this answer by extending wmky's answer above & also, assuming that you've configured mysql for your metastore instead of derby.
select PART_NAME FROM PARTITIONS WHERE TBL_ID=(SELECT TBL_ID FROM TBLS WHERE TBL_NAME='<table_name>');
The above query gives you all possible values of the partition columns.
Example:
hive> desc clicks_fact;
OK
time timestamp
..
day date
file_date varchar(8)
# Partition Information
# col_name data_type comment
day date
file_date varchar(8)
Time taken: 1.075 seconds, Fetched: 28 row(s)
I'm going to fetch the values of partition columns.
mysql> select PART_NAME FROM PARTITIONS WHERE TBL_ID=(SELECT TBL_ID FROM TBLS WHERE TBL_NAME='clicks_fact');
+-----------------------------------+
| PART_NAME |
+-----------------------------------+
| day=2016-08-16/file_date=20160816 |
| day=2016-08-17/file_date=20160816 |
....
....
| day=2017-09-09/file_date=20170909 |
| day=2017-09-08/file_date=20170909 |
| day=2017-09-09/file_date=20170910 |
| day=2017-09-10/file_date=20170910 |
+-----------------------------------+
1216 rows in set (0.00 sec)
Returns all partition columns.
Note: JOIN table DBS ON DB_ID when there is a DB involved (i.e, when, multiple DB's have same table_name)