Question

我在Cassandra有桌子：

CREATE TABLE test (
 bucket int,  
 start timestamp,
 end timestamp,  
 PRIMARY KEY((bucket),start, end)
);

我想得到一个类似的查询：

SELECT * FROM test where bucket = 1 and start <= current_time and end >= current_time

换句话说，我想找到包含给定时间戳的间隔。

我知道查询错了。我也尝试使用多列切片限制，但在这种情况下它也没用。有没有办法做到这一点？

Answer 1

我过去也遇到过类似的问题。我这样做的方法是使用一列来跟踪开始/结束。然后有一行用于事件的开始，一行用于结束。让我们尝试创建一个表来存储＆＃34; Nerd Holidays，＆＃34;像这样：

CREATE TABLE nerd_holidays (
  month_bucket int,  
  event_time timestamp,
  beginend text,  
  name text,
  PRIMARY KEY ((month_bucket), event_time, beginend)
) WITH CLUSTERING ORDER BY (event_time DESC, beginend ASC);

我会插入一些行：

INSERT INTO nerd_holidays (month_bucket, event_time, beginend, name)
VALUES (3,'2018-03-14 00:00:00','begin','Pi Day');
INSERT INTO nerd_holidays (month_bucket, event_time, beginend, name)
VALUES (3,'2018-03-14 23:59:59','end','Pi Day');
INSERT INTO nerd_holidays (month_bucket, event_time, beginend, name)
VALUES (5,'2018-05-04 00:00:00','begin','Star Wars Day');
INSERT INTO nerd_holidays (month_bucket, event_time, beginend, name)
VALUES (5,'2018-05-04 23:59:59','end','Star Wars Day');
INSERT INTO nerd_holidays (month_bucket, event_time, beginend, name)
VALUES (9,'2018-09-19 00:00:00','begin','Talk Like a Pirate Day');
INSERT INTO nerd_holidays (month_bucket, event_time, beginend, name)
VALUES (9,'2018-09-19 23:59:59','end','Talk Like a Pirate Day');
INSERT INTO nerd_holidays (month_bucket, event_time, beginend, name)
VALUES (9,'2018-09-25 00:00:00','begin','Hobbit Day');
INSERT INTO nerd_holidays (month_bucket, event_time, beginend, name)
VALUES (9,'2018-09-25 23:59:59','end','Hobbit Day');

现在我可以查询9月份特定时间的数据，如下所示：

cassdba@cqlsh:stackoverflow> SELECT * FROM nerd_holidays
    WHERE month_bucket=9
    AND event_time >= '2018-09-18 00:00'
    AND event_time <= '2018-09-19 08:33' ;

 month_bucket | event_time                      | beginend | name
--------------+---------------------------------+----------+------------------------
            9 | 2018-09-19 05:00:00.000000+0000 |    begin | Talk Like a Pirate Day

(1 rows)

正如你所看到的，＆＃34;像海盗日那样谈话＆＃34;在请求的日期范围内开始。

Cassandra - 获取间隔包含给定的时间戳

1 个答案: