Width_bucket function
The following is an example of a width_bucket function:
SELECT quarter, city, profit_margin, width_bucket(profit_margin, 15,
21, 3) FROM sales_tbl where quarter = 2 or quarter = 3 ORDER BY
quarter, city;
QUARTER | CITY | PROFIT_MARGIN | ?COLUMN?
---------+-------------+---------------+----------
2 | Atlanta | 12 | 0
2 | Baltimore | 21 | 4
2 | Boston | 20 | 3
2 | Los Angeles | 15 | 1
2 | New York | 20 | 3
2 | Seattle | 15 | 1
3 | Atlanta | 15 | 1
3 | Baltimore | 22 | 4
3 | Boston | 21 | 4
3 | Los Angeles | 17 | 2
3 | New York | 22 | 4
3 | Seattle | 18 | 2
(12 rows)In this example, in the first row, the profit margin of 12 is less than the beginning value, so it is assigned to the underflow bucket. The row with a profit margin of 22 are greater than the end value, so they are assigned to the overflow bucket.
If you create a histogram of the profit margins for each city in quarters 2 and 3, the buckets are as follows: [15, 17) [17, 19) and [19, 21)