时间戳/日期作为cassandra列族/ hector的键 [英] Timestamp / date as key for cassandra column family / hector

问题描述

我必须创建和查询一个列族作为[timestamp，long]。另外，
在查询时我想对时间戳的范围查询（如xxx和yyy之间的时间戳）这是可能吗？

I have to create and query a column family with composite key as [timestamp,long]. Also, while querying I want to fire range query for timestamp (like timestamp between xxx and yyy) Is this possible ?

目前我在做一些很有趣的事（我知道它不正确）。我为给定范围创建带有时间戳字符串的键，并与long连接。

Currently I am doing something really funny (Which I know its not correct). I create keys with timestamp string for given range and concatenate with long.

like ,
1254345345435-1234
3423432423432-1234
1231231231231-9999

并将一组键传递给hector api。 （所以如果我有1个月的日期范围，我想要每分钟的数据，我创建30 * 24 * 60 * [次要键 - 长]）

and pass set of keys to hector api. (so if i have date range for 1 month and I want every minute data, i create 30 * 24 * 60 * [number of secondary key - long])

可以解决组合键的连接问题。但查询部分是我想要了解的。

I can solve concatenation issue with composite key. But query part is what I am trying to understand.

据我所知，由于我们使用RandomPartitioner，我们不能真正基于范围查询，因为键是MD5校验和。这种用例的理想设计是什么？

As far as I understood, As we are using RandomPartitioner we cannot really query based on range as keys are MD5 checksum. Whats ideal design for this kind of use case ?

我的架构和要求如下：（actual csh）

my schema and requirements are as follows : (actual csh)

    CREATE TABLE report(
        ts timestamp,
        user_id long,
        svc1 long,
        svc2 long,
        svc3 long,
        PRIMARY KEY(ts, user_id));

select from report where ts between (123445345435 and 32423423424) and user_id is in (123,567,987)

推荐答案

您不能对复合键的第一个组件进行范围查询。相反，您应该写一个哨兵值，例如daystamp（当前日午夜的unix纪元）作为键，然后写一个复合列作为timestamp：long。这样，您可以提供组成范围的键，并在复合列的时间戳组件上切片。

You cannot do range queries on the first component of a composite key. Instead, you should write a sentinel value such as a daystamp (the unix epoch at midnight on the current day) as the key, then write a composite column as timestamp:long. This way you can provide the keys that comprise your range, and slice on the timestamp component of the composite column.

这篇关于时间戳/日期作为cassandra列族/ hector的键的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！