Any aggregate function (used with the OVER clause) can also be used as a window function
sachi=# select x, row_number() over() from generate_series(1, 15, 2) as t(x); x | row_number ----+------------ 1 | 1 3 | 2 5 | 3 7 | 4 9 | 5 11 | 6 13 | 7 15 | 8 (8 rows) On-Line Analytic Processing: The purpose of OLAP is to quickly provide answers to multi-dimensional queries. “Window” Functions: Allow access to multiple rows in a single table scan. OLAP Grouping Extensions: Similar to GROUP BY but much more flexible. For example
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