Question

我正在尝试计算Amazon Redshift中的每月保留率，并提出以下问题：

Query 1

SELECT EXTRACT(year FROM activity.created_at) AS Year,
       EXTRACT(month FROM activity.created_at) AS Month,
       COUNT(DISTINCT activity.member_id) AS active_users,
       COUNT(DISTINCT future_activity.member_id) AS retained_users,
       COUNT(DISTINCT future_activity.member_id) / COUNT(DISTINCT activity.member_id)::float AS retention
FROM ads.fbs_page_view_staging activity
  LEFT JOIN ads.fbs_page_view_staging AS future_activity
         ON activity.mongo_id = future_activity.mongo_id
AND datediff ('month',activity.created_at,future_activity.created_at) = 1
GROUP BY Year,
         Month
ORDER BY Year,
         Month

由于某种原因，此查询会返回zero retained_users和zero retention。我很感激有关为什么会发生这种情况的任何帮助，或者可能会有一个完全不同的月保留查询。

我根据另一个SO帖子修改了查询，在这里：

Query 2

WITH t AS (
   SELECT member_id
         ,date_trunc('month', created_at) AS month
         ,count(*) AS item_transactions
         ,lag(date_trunc('month', created_at)) OVER (PARTITION BY  member_id
                                           ORDER BY date_trunc('month', created_at)) 
          = date_trunc('month', created_at) - interval '1 month'
            OR NULL AS repeat_transaction
   FROM   ads.fbs_page_view_staging
   WHERE  created_at >= '2016-01-01'::date
   AND    created_at <  '2016-04-01'::date -- time range of interest.
   GROUP  BY 1, 2
   )
SELECT month
      ,sum(item_transactions) AS num_trans
      ,count(*) AS num_buyers
      ,count(repeat_transaction) AS repeat_buyers
      ,round(
          CASE WHEN sum(item_transactions) > 0
             THEN count(repeat_transaction) / sum(item_transactions) * 100
             ELSE 0
          END, 2) AS buyer_retention
FROM   t
GROUP  BY 1
ORDER  BY 1;

此查询给出了以下错误：

An error occurred when executing the SQL command:
WITH t AS (
   SELECT member_id
         ,date_trunc('month', created_at) AS month
         ,count(*) AS item_transactions
         ,lag(date_trunc('m...

[Amazon](500310) Invalid operation: Interval values with month or year parts are not supported
Details: 
 -----------------------------------------------
  error:  Interval values with month or year parts are not supported
  code:      8001
  context:   interval months: "1"
  query:     616822
  location:  cg_constmanager.cpp:145
  process:   padbmaster [pid=15116]
  -----------------------------------------------;

我觉得Query 2比Query 1更好，所以我更愿意修正错误。

非常感谢任何帮助。

Answer 1

查询1看起来不错。我试过类似的。见下文。您正在使用表上的自联接（ads.fbs_page_view_staging）和相同的列（created_at）。假设mongo_id是唯一的，datediff('month'....)将始终返回0，datediff ('month',activity.created_at,future_activity.created_at) = 1将始终为false。

-- Count distinct events of join_col_id that have lapsed for one month.
SELECT count(distinct E.join_col_id) dist_ct
FROM public.fact_events E
JOIN public.dim_table Z
  ON E.join_col_id = Z.join_col_id
WHERE datediff('month', event_time, sysdate) = 1;

-- 2771654 -- dist_ct

亚马逊红移的每月保留率

1 个答案: