RETENTION
RETENTION
description
Syntax
retention(event1, event2, ... , eventN);
留存函数将一组条件作为参数，类型为1到32个UInt8类型的参数，用来表示事件是否满足特定条件。 任何条件都可以指定为参数.
除了第一个以外，条件成对适用：如果第一个和第二个是真的，第二个结果将是真的，如果第一个和第三个是真的，第三个结果将是真的，等等。
简单来讲，返回值数组第1位表示event1的真假，第二位表示event1真假与event2真假相与，第三位表示event1真假与event3真假相与，等等。如果event1为假，则返回全是0的数组。
Arguments
event — 返回UInt8结果（1或0）的表达式.
Returned value
由1和0组成的最大长度为32位的数组，最终输出数组的长度与输入参数长度相同。
1 — 条件满足。
0 — 条件不满足
example
DROP TABLE IF EXISTS retention_test;
CREATE TABLE retention_test(
`uid` int COMMENT 'user id',
`date` datetime COMMENT 'date time'
)
DUPLICATE KEY(uid)
DISTRIBUTED BY HASH(uid) BUCKETS 3
PROPERTIES (
"replication_num" = "1"
);
INSERT into retention_test (uid, date) values (0, '2022-10-12'),
(0, '2022-10-13'),
(0, '2022-10-14'),
(1, '2022-10-12'),
(1, '2022-10-13'),
(2, '2022-10-12');
SELECT * from retention_test;
+------+---------------------+
| uid | date |
+------+---------------------+
| 0 | 2022-10-14 00:00:00 |
| 0 | 2022-10-13 00:00:00 |
| 0 | 2022-10-12 00:00:00 |
| 1 | 2022-10-13 00:00:00 |
| 1 | 2022-10-12 00:00:00 |
| 2 | 2022-10-12 00:00:00 |
+------+---------------------+
SELECT
uid,
retention(date = '2022-10-12')
AS r
FROM retention_test
GROUP BY uid
ORDER BY uid ASC;
+------+------+
| uid | r |
+------+------+
| 0 | [1] |
| 1 | [1] |
| 2 | [1] |
+------+------+
SELECT
uid,
retention(date = '2022-10-12', date = '2022-10-13')
AS r
FROM retention_test
GROUP BY uid
ORDER BY uid ASC;
+------+--------+
| uid | r |
+------+--------+
| 0 | [1, 1] |
| 1 | [1, 1] |
| 2 | [1, 0] |
+------+--------+
SELECT
uid,
retention(date = '2022-10-12', date = '2022-10-13', date = '2022-10-14')
AS r
FROM retention_test
GROUP BY uid
ORDER BY uid ASC;
+------+-----------+
| uid | r |
+------+-----------+
| 0 | [1, 1, 1] |
| 1 | [1, 1, 0] |
| 2 | [1, 0, 0] |
+------+-----------+
keywords
RETENTION