云量指数:每个时间段的唯一身份用户数 [英] cloudant index: count number of unique users per time period

问题描述

此处发表了与此问题非常相似的帖子.在cloudant中，我有一个文档结构，用于存储用户访问应用程序时的内容，如下所示:

A very similar post was made about this issue here. In cloudant, I have a document structure storing when users access an application, that looks like the following:

{"username":"one","timestamp":"2015-10-07T15:04:46Z"} --- |同一天 {"username":"one","timestamp":"2015-10-07T19:22:00Z"} --- ^
{"username":"one","timestamp":"2015-10-25T04:22:00Z"}
{"username":"two","timestamp":"2015-10-07T19:22:00Z"}

{"username":"one","timestamp":"2015-10-07T15:04:46Z"}---| same day {"username":"one","timestamp":"2015-10-07T19:22:00Z"}---^
{"username":"one","timestamp":"2015-10-25T04:22:00Z"}
{"username":"two","timestamp":"2015-10-07T19:22:00Z"}

我想知道的是计算给定时间段内的唯一身份用户数.例如:

What I want to know is to count the # of unique users for a given time period. Ex:

2015-10-07 = {"count": 2} 2015年10月7日访问了两个不同的用户
2015-10-25 = {"count": 1} 2015年10月25日访问了另一个用户
2015 = {"count" 2} 2015年访问了两个不同的用户

2015-10-07 = {"count": 2} two different users accessed on 2015-10-07
2015-10-25 = {"count": 1} one different user accessed on 2015-10-25
2015 = {"count" 2} two different users accessed in 2015

这一切都变得很棘手，因为例如在2015-10-07上，用户名:一个具有两次访问时间的记录，但它只应返回不重复总数的1用户.

This all just becomes tricky because for example on 2015-10-07, username: one has two records of when they accessed, but it should only return a count of 1 to the total of unique users.

我尝试过:

function(doc) {
    var time = new Date(Date.parse(doc['timestamp'])); 
    emit([time.getUTCFullYear(),time.getUTCMonth(),time.getUTCDay(),doc.username], 1);
}

这有几个问题，耶稣·阿尔瓦(Jesus Alva)在我上面链接的帖子中发表了评论.

This suffers from several issues, which are highlighted by Jesus Alva who commented in the post I linked to above.

谢谢！

推荐答案

也许有更好的方法，但是却无济于事...

There's probably a better way of doing this, but off the top of my head ...

您可以尝试为每个粒度级别发出一个索引:

You could try emitting an index for each level of granularity:

function(doc) {
    var time = new Date(Date.parse(doc['timestamp'])); 
    var year = time.getUTCFullYear();
    var month = time.getUTCMonth()+1;
    var day = time.getUTCDate();

    // day granularity
    emit([year,month,day,doc.username], null);

    // year granularity
    emit([year,doc.username], null);
}

// reduce function - `_count`

每日查询(2015-10-07):

Day query (2015-10-07):

inclusive_end=true&
start_key=[2015, 10, 7, "\u0000"]&
end_key=[2015, 10, 7, "\uefff"]&
reduce=true&
group=true

日查询结果-您的应用程序代码将计算行数:

Day query result - your application code would count the number of rows:

{"rows":[
  {"key":[2015,10,7,"one"],"value":2},
  {"key":[2015,10,7,"two"],"value":1}
]}

年度查询:

inclusive_end=true&
start_key=[2015, "\u0000"]&
end_key=[2015, "\uefff"]&
reduce=true&
group=true

查询结果-您的应用程序代码将计算行数:

Query result - your application code would count the number of rows:

{"rows":[
  {"key":[2015,"one"],"value":3},
  {"key":[2015,"two"],"value":1}
]}

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