Greenplum built-in windows functions

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

• 1. Standard GROUP BY Example

  2. ROLLUP

  3. GROUPING SETS

  4. CUBE 

  5. grouping(column [, ...]) function

  6. group_id() function