Accumulo是否支持聚合？ [英] Does Accumulo support aggregation?

问题描述

我是Accumulo的新手。我知道我可以使用Hadoop和MapReduce编写Java代码来扫描，插入，更新和删除数据。我想知道的是，在Accumulo中是否可以进行聚合。

I am new to Accumulo. I know that I can write Java code to scan, insert, update and delete data using Hadoop and MapReduce. What I would like to know is whether aggregation is possible in Accumulo.

我知道在MySql中我们可以使用 groupby ， orderby ， max ， min ， count ， sum ， join ，嵌套查询等。它们是否有可能直接或间接在Accumulo中使用这些功能。

I know that in MySql we can use groupby,orderby,max,min,count,sum,joins, nested queries, etc. Is their is any possibility to use these functions in Accumulo either directly or indirectly.

推荐答案

Accumulo通过使用组合器迭代器（ Accumulo合并器示例）。

Accumulo does support aggregation through the use of combiner iterators (Accumulo Combiner Example ).

迭代器主要在服务器端运行，但可以在客户端运行，并且可以执行很多计算，然后再将数据发送回客户端。

Iterators mostly run server-side, but can be run client-side, and can perform quite a bit of computation before sending the data back to your client.

Accumulo附带了许多迭代器，更具体地说，summingCombiner用于对条目的值求和。 Dave Medinet的博客中有一些很好的例子（ Accumulo博客）。更具体地说，使用summingCombiner实施字数统计（ Accumulo ）。我还建议注册Accumulo用户邮件列表（邮件列表）。

Accumulo comes packaged with many iterators, more specifically the summingCombiner is used to sum the values of entries. Dave Medinet's has a blog that has some good examples (Accumulo Blog). More specifically, using the summingCombiner to implement wordcount (Word Count in Accumulo). I also suggest signing up for the Accumulo users mailing lists (mailing lists).

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