SEQUENCE_COUNT | SelectDB

SEQUENCE-COUNT

Description

Syntax

sequence_count(pattern, timestamp, cond1, cond2, ...);

计算与模式匹配的事件链的数量。该函数搜索不重叠的事件链。当前链匹配后，它开始搜索下一个链。

警告!

在同一秒钟发生的事件可能以未定义的顺序排列在序列中，会影响最终结果。

Arguments

pattern — 模式字符串.

模式语法

(?N) — 在位置N匹配条件参数。条件在编号 [1, 32] 范围。例如, (?1) 匹配传递给 cond1 参数。

.* — 匹配任何事件的数字。不需要条件参数来匹配这个模式。

(?t operator value) — 分开两个事件的时间。单位为秒。

t表示为两个时间的差值，单位为秒。例如： (?1)(?t>1800)(?2) 匹配彼此发生超过1800秒的事件， (?1)(?t>10000)(?2)匹配彼此发生超过10000秒的事件。这些事件之间可以存在任意数量的任何事件。您可以使用 >=, >, <, <=, == 运算符。

timestamp — 包含时间的列。典型的时间类型是： Date 和 DateTime。也可以使用任何支持的 UInt 数据类型。

cond1, cond2 — 事件链的约束条件。数据类型是： UInt8。最多可以传递32个条件参数。该函数只考虑这些条件中描述的事件。如果序列包含未在条件中描述的数据，则函数将跳过这些数据。

Returned value

匹配的非重叠事件链数。

example

匹配例子

DROP TABLE IF EXISTS sequence_count_test1;
 
CREATE TABLE sequence_count_test1(
                `uid` int COMMENT 'user id',
                `date` datetime COMMENT 'date time', 
                `number` int NULL COMMENT 'number' 
                )
DUPLICATE KEY(uid) 
DISTRIBUTED BY HASH(uid) BUCKETS 3 
PROPERTIES ( 
    "replication_num" = "1"
); 
 
INSERT INTO sequence_count_test1(uid, date, number) values (1, '2022-11-02 10:41:00', 1),
                                                   (2, '2022-11-02 13:28:02', 2),
                                                   (3, '2022-11-02 16:15:01', 1),
                                                   (4, '2022-11-02 19:05:04', 2),
                                                   (5, '2022-11-02 20:08:44', 3); 
 
SELECT * FROM sequence_count_test1 ORDER BY date;
 
+------+---------------------+--------+
| uid  | date                | number |
+------+---------------------+--------+
|    1 | 2022-11-02 10:41:00 |      1 |
|    2 | 2022-11-02 13:28:02 |      2 |
|    3 | 2022-11-02 16:15:01 |      1 |
|    4 | 2022-11-02 19:05:04 |      2 |
|    5 | 2022-11-02 20:08:44 |      3 |
+------+---------------------+--------+
 
SELECT sequence_count('(?1)(?2)', date, number = 1, number = 3) FROM sequence_count_test1;
 
+----------------------------------------------------------------+
| sequence_count('(?1)(?2)', `date`, `number` = 1, `number` = 3) |
+----------------------------------------------------------------+
|                                                              1 |
+----------------------------------------------------------------+
 
SELECT sequence_count('(?1)(?2)', date, number = 1, number = 2) FROM sequence_count_test1;
 
+----------------------------------------------------------------+
| sequence_count('(?1)(?2)', `date`, `number` = 1, `number` = 2) |
+----------------------------------------------------------------+
|                                                              2 |
+----------------------------------------------------------------+
 
SELECT sequence_count('(?1)(?t>=3600)(?2)', date, number = 1, number = 2) FROM sequence_count_test1;
 
+---------------------------------------------------------------------------+
| sequence_count('(?1)(?t>=3600)(?2)', `date`, `number` = 1, `number` = 2) |
+---------------------------------------------------------------------------+
|                                                                         2 |
+---------------------------------------------------------------------------+

不匹配例子

DROP TABLE IF EXISTS sequence_count_test2;
 
CREATE TABLE sequence_count_test2(
                `uid` int COMMENT 'user id',
                `date` datetime COMMENT 'date time', 
                `number` int NULL COMMENT 'number' 
                )
DUPLICATE KEY(uid) 
DISTRIBUTED BY HASH(uid) BUCKETS 3 
PROPERTIES ( 
    "replication_num" = "1"
); 
 
INSERT INTO sequence_count_test2(uid, date, number) values (1, '2022-11-02 10:41:00', 1),
                                                   (2, '2022-11-02 11:41:00', 7),
                                                   (3, '2022-11-02 16:15:01', 3),
                                                   (4, '2022-11-02 19:05:04', 4),
                                                   (5, '2022-11-02 21:24:12', 5);
 
SELECT * FROM sequence_count_test2 ORDER BY date;
 
+------+---------------------+--------+
| uid  | date                | number |
+------+---------------------+--------+
|    1 | 2022-11-02 10:41:00 |      1 |
|    2 | 2022-11-02 11:41:00 |      7 |
|    3 | 2022-11-02 16:15:01 |      3 |
|    4 | 2022-11-02 19:05:04 |      4 |
|    5 | 2022-11-02 21:24:12 |      5 |
+------+---------------------+--------+
 
SELECT sequence_count('(?1)(?2)', date, number = 1, number = 2) FROM sequence_count_test2;
 
+----------------------------------------------------------------+
| sequence_count('(?1)(?2)', `date`, `number` = 1, `number` = 2) |
+----------------------------------------------------------------+
|                                                              0 |
+----------------------------------------------------------------+
 
SELECT sequence_count('(?1)(?2).*', date, number = 1, number = 2) FROM sequence_count_test2;
 
+------------------------------------------------------------------+
| sequence_count('(?1)(?2).*', `date`, `number` = 1, `number` = 2) |
+------------------------------------------------------------------+
|                                                                0 |
+------------------------------------------------------------------+
 
SELECT sequence_count('(?1)(?t>3600)(?2)', date, number = 1, number = 7) FROM sequence_count_test2;
 
+--------------------------------------------------------------------------+
| sequence_count('(?1)(?t>3600)(?2)', `date`, `number` = 1, `number` = 7) |
+--------------------------------------------------------------------------+
|                                                                        0 |
+--------------------------------------------------------------------------+

特殊例子

DROP TABLE IF EXISTS sequence_count_test3;
 
CREATE TABLE sequence_count_test3(
                `uid` int COMMENT 'user id',
                `date` datetime COMMENT 'date time', 
                `number` int NULL COMMENT 'number' 
                )
DUPLICATE KEY(uid) 
DISTRIBUTED BY HASH(uid) BUCKETS 3 
PROPERTIES ( 
    "replication_num" = "1"
); 
 
INSERT INTO sequence_count_test3(uid, date, number) values (1, '2022-11-02 10:41:00', 1),
                                                   (2, '2022-11-02 11:41:00', 7),
                                                   (3, '2022-11-02 16:15:01', 3),
                                                   (4, '2022-11-02 19:05:04', 4),
                                                   (5, '2022-11-02 21:24:12', 5);
 
SELECT * FROM sequence_count_test3 ORDER BY date;
 
+------+---------------------+--------+
| uid  | date                | number |
+------+---------------------+--------+
|    1 | 2022-11-02 10:41:00 |      1 |
|    2 | 2022-11-02 11:41:00 |      7 |
|    3 | 2022-11-02 16:15:01 |      3 |
|    4 | 2022-11-02 19:05:04 |      4 |
|    5 | 2022-11-02 21:24:12 |      5 |
+------+---------------------+--------+

Perform the query:

SELECT sequence_count('(?1)(?2)', date, number = 1, number = 5) FROM sequence_count_test3;
 
+----------------------------------------------------------------+
| sequence_count('(?1)(?2)', `date`, `number` = 1, `number` = 5) |
+----------------------------------------------------------------+
|                                                              1 |
+----------------------------------------------------------------+

上面为一个非常简单的匹配例子，该函数找到了数字5跟随数字1的事件链。它跳过了它们之间的数字7，3，4，因为该数字没有被描述为事件。如果我们想在搜索示例中给出的事件链时考虑这个数字，我们应该为它创建一个条件。

现在，考虑如下执行语句：

SELECT sequence_count('(?1)(?2)', date, number = 1, number = 5, number = 4) FROM sequence_count_test3;
 
+------------------------------------------------------------------------------+
| sequence_count('(?1)(?2)', `date`, `number` = 1, `number` = 5, `number` = 4) |
+------------------------------------------------------------------------------+
|                                                                            0 |
+------------------------------------------------------------------------------+

您可能对这个结果有些许疑惑，在这种情况下，函数找不到与模式匹配的事件链，因为数字4的事件发生在1和5之间。如果在相同的情况下，我们检查了数字6的条件，则序列将与模式匹配。

SELECT sequence_count('(?1)(?2)', date, number = 1, number = 5, number = 6) FROM sequence_count_test3;
 
+------------------------------------------------------------------------------+
| sequence_count('(?1)(?2)', `date`, `number` = 1, `number` = 5, `number` = 6) |
+------------------------------------------------------------------------------+
|                                                                            1 |
+------------------------------------------------------------------------------+

keywords

SEQUENCE_COUNT

RETENTION SEQUENCE_MATCH