Gbase 8A OLAP analysis function cume_ Example of dist

GBase 8a Support cume_dist function , Used to calculate less than or equal to or greater than ( according to order The order of ) Percentage of this value .

grammar

cume_disk() over([partition by ] order by [desc])

explain
among partition Whether to open a window , Otherwise, all values shall be treated uniformly .

order by The order of ,ASC（ Default ) = Less than or equal to ,DESC = Greater than or equal to

Examples
Less than or equal to
The following example is the default ascending order , The first line means ： Less than or equal to value 1 The proportion of rows of is 20%

gbase> select id,cume_dist()over(order by id) cr from t2;
+------+-----+
| id   | cr  |
+------+-----+
|    1 | 0.2 |
|    2 | 0.4 |
|    3 | 0.6 |
|    4 | 0.8 |
|    5 |   1 |
+------+-----+
5 rows in set (Elapsed: 00:00:00.01)

Greater than or equal to
The order is desc, The first line means ： A value greater than or equal to 5 The proportion of rows of is 20%.

gbase> select id,cume_dist()over(order by id desc) cr from t2;
+------+-----+
| id   | cr  |
+------+-----+
|    5 | 0.2 |
|    4 | 0.4 |
|    3 | 0.6 |
|    2 | 0.8 |
|    1 |   1 |
+------+-----+
5 rows in set (Elapsed: 00:00:00.02)

With window partition
Every partition The percentages are not calculated separately .

gbase> select * from t4;
+------+------+
| id   | type |
+------+------+
|    1 | A    |
|    2 | A    |
|    3 | A    |
|    1 | B    |
|    2 | B    |
|    3 | B    |
|    4 | B    |
+------+------+
7 rows in set (Elapsed: 00:00:00.00)

gbase> select type,id,cume_dist()over(partition by type order by id) cr from t4;
+------+------+-------------------+
| type | id   | cr                |
+------+------+-------------------+
| A    |    1 | 0.333333333333333 |
| A    |    2 | 0.666666666666667 |
| A    |    3 |                 1 |
| B    |    1 |              0.25 |
| B    |    2 |               0.5 |
| B    |    3 |              0.75 |
| B    |    4 |                 1 |
+------+------+-------------------+
7 rows in set (Elapsed: 00:00:00.07)

And Percent_rank Comparison of
percent_rank Is to calculate the relative position , Including the starting point 0, and cume_dist It contains equal to , So it won't show up 0. If the data is only 1 That's ok , that percent_rank For what time 0, and cume_dist by 1（100%）.

gbase> select id,cume_dist()over(order by id) cr,percent_rank()over(order by id) pr  from t2;
+------+-----+------+
| id   | cr  | pr   |
+------+-----+------+
|    1 | 0.2 |    0 |
|    2 | 0.4 | 0.25 |
|    3 | 0.6 |  0.5 |
|    4 | 0.8 | 0.75 |
|    5 |   1 |    1 |
+------+-----+------+
5 rows in set (Elapsed: 00:00:00.01)

A line of data

gbase> select id,cume_dist()over(order by id) cr,percent_rank()over(order by id) pr  from t5;
+------+----+----+
| id   | cr | pr |
+------+----+----+
|    1 |  1 |  0 |
+------+----+----+
1 row in set (Elapsed: 00:00:00.02)