About Global Variables and Logical Table Source Fragmentation

You can use global variables in a logical table source's fragmentation expression to automatically modify a fragment's content.

For example, suppose you have two sources for information about orders where one source contains recent orders and the other source contains historical data. You need to update the global variable to use the recent orders and move the historical order data to a different view. Without using global variables, you would describe the content of the source containing recent data with an expression such as:

Orders.OrderDates."Order Date" >= TIMESTAMP '2001-06-02 00:00:00'

This content statement becomes invalid as new data is added to the recent source and older data is moved to the historical source. To accurately reflect the new content of the recent source, you would have to modify the fragmentation content description manually. Instead you can define global variables to automatically modify the content.