用于登录Cassandra的DataModel用例 [英] DataModel use case for logging in Cassandra

问题描述

我正在尝试在Cassandra中设计应用程序日志表，

I am trying to design the application log table in Cassandra,

CREATE TABLE log(
  yyyymmdd varchar, 
  created timeuuid,  
  logMessage text,
  module text, 
  PRIMARY KEY(yyyymmdd, created)
);

现在，当我尝试执行以下查询时，它按预期运行，

Now when I try to perform the following queries it is working as expected,

select * from log where yymmdd = '20182302' LIMIT 50;

以上查询没有分组，是全局的。

Above query is without grouping, kind of global.

当前，我为模块做了一个二级索引，因此我能够执行以下操作，

Currently I did an secondary index for 'module' so I am able to perform the following,

select * from log where yymmdd = '20182302' WHERE module LIKE 'test' LIMIT 50;     

现在，我担心的是没有做 二级索引 ，是否有基于模块查询和获取数据的有效方法（或）是否有更好的设计？

Now my concern is without doing the secondary index, Is there an efficient way to query based on the module and fetch the data (or) Is there a better design?

也请让我知道当前设计中的性能问题。

Also let me know the performance issue in current design.

推荐答案

对于基于模块和日期的获取，您只能使用另一个表，如下所示：

For fetching based on module and date, you can only use another table, like this:

CREATE TABLE module_log(
  yyyymmdd varchar, 
  created timeuuid,  
  logMessage text,
  module text, 
  PRIMARY KEY((module,yyyymmdd), created)
);

这将允许对模块的每种组合使用单个分区& yyyymmdd 值，因此分区不会非常宽。

This will allow to have single partition for every combination of the module & yyyymmdd values, so you won't have very wide partitions.

此外，请注意，如果创建了仅在 module 字段上的二级索引-您可能会遇到分区太大的问题（我假设您的 module 值？）。

Also, take into account that if you created a secondary index only on module field - you may get problems with too big partitions (I assume that you have very limited number of module values?).

PS您使用的是纯Cassandra还是DSE？

P.S. Are you using pure Cassandra, or DSE?

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