Issue with Very Large Table with 1000's of partitions/subpartitions.

I have a very large table that is partitioned by date and subpartitioned by hash. The date partition is per day since 2008 thru 2012. The subpartitions are 16 partitions hashed. Each partition is in its own tablespace with all 16 subpartitions in that same tablespace.

partitions names follow the following format PYYYYMMDD

I have ran into an issue with querying this table as i will explain.

If i execute the following query things work ok,

Select count(*) from tablea where calldate >= to_date('02/23/2012','MM/DD/YYYYY');

However if i do the following the query seems to never come back (killed after several hours).