Sorting CQL3更改主键

假设我有一张如下组成的表格

CREATE TABLE rollup (
  hashname text,
  key text,
  day timestamp,
  counter_value counter,
  PRIMARY KEY (hashname, key, day)
) WITH
...

我想运行一个如下所示的查询

SELECT * FROM rollup WHERE hashname='some_namespaced_hash' AND day>='2013-07-15' AND day<='2013-07-25';

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SELECT*FROM rollup，其中hashname='some\u namespaced\u hash'和day>='2013-07-15'和day您是对的，唯一的方法是切换主键的顺序。原因是，目前，您的密钥按以下顺序排列：

hashname1 key1 day1: counter_value111
hashname1 key1 day2: counter_value112
hashname1 key2 day1: counter_value121
hashname1 key2 day2: counter_value122
hashname1 key3 day1: counter_value131
hashname1 key3 day2: counter_value132

hashname1 day1 key1: counter_value111
hashname1 day1 key2: counter_value121
hashname1 day1 key3: counter_value131
hashname1 day2 key1: counter_value112
hashname1 day2 key2: counter_value122
hashname1 day2 key3: counter_value132

因此，要检索天数范围，Cassandra需要为每个键“跳过”。这是低效的，不受支持。您需要按以下顺序安装：

hashname1 key1 day1: counter_value111
hashname1 key1 day2: counter_value112
hashname1 key2 day1: counter_value121
hashname1 key2 day2: counter_value122
hashname1 key3 day1: counter_value131
hashname1 key3 day2: counter_value132

hashname1 day1 key1: counter_value111
hashname1 day1 key2: counter_value121
hashname1 day1 key3: counter_value131
hashname1 day2 key1: counter_value112
hashname1 day2 key2: counter_value122
hashname1 day2 key3: counter_value132

不幸的是，唯一的方法是重写所有数据，而Cassandra中没有内置的方法。您可以编写一个脚本来执行此操作，方法是从一个CF读入数据，按顺序切换，然后写出一个新CF并切换。如果这需要在现场进行，则难度更大，但仍有可能