Interrow functions are OLAP functions that access previous rows or subsequent rows in a data series without requiring you to define a self-join. These two interrow functions have been added:
LAG – provides access to a row at a given physical offset prior to the CURRENT ROW in the table.
LEAD – provides access to a row at a given physical offset after the CURRENT ROW in the table.
A ranking function has also been added:
ROW_NUMBER – a ranking function that assigns a row number for each row in a window partition, restarting the numbering at each new partition. If you did not define window partitions, the function assigns unique row numbers for the complete result set.
See Reference: Building Blocks, Tables, and Procedures > SQL Functions and System Administration Guide: Volume 2 > Using OLAP.
