So i need unlimited length data type for required column of the table for storing the large values
is there any issue to use unlimited length datatype text for the required column of the table instead of using varchar ?
Between the two you should use the "text" data type for those columns. You will need to describe your use case in more detail if you want input as to whether you need to use the large object API instead.
The database cannot store an unlimited amount of data in a single row+column (cell) - you will still encounter a physical limit to the number of bytes able to be stored in a single cell when using text.