Table Partition - response (6) by M.Saeed Khurram

Hi Sharat,
Here is the answer to your question:
http://www.info.teradata.com/htmlpubs/DB_TTU_14_00/index.html#page/Database_Management/B035_1094_111A/ch09.050.084.html
 
See the lines:
You can optimize the effects of using RANGE_N in your partitioning expression by observing the following guidelines:

Reference only a single integer (BYTEINT, SMALLINT, INTEGER, BIGINT), character (CHARACTER, GRAPHIC, VARCHAR, VARGRAPHIC), DATE, or TIMESTAMP column, not expressions.

For example, specifying a simple expression such as  in place of a column name in the RANGE_N specification, even if the expression references only a single column, can hinder, or even prevent, row partition elimination.